The Genetics of Autism


Approximately 10% of the cases of autism are probably in some way genetically derived.  In other words they have taken place due to the genes of the parents and, if neither of the parents are ASD affected, it would be reasonable to expect that only 1 in 4 of further children would have the conditions.  However, this single gene idea is simply not reasonable in that even if one of identical twins (i.e. with all their genes the same; monozygotic) there is only a 93% that the other will be.  The statistics for non-identical twins shows that they also have a decent chance of having autism if one has it (but this data is wide with 0% to 40% chances have been reported).  The excess of ASD in boys is quite clear in that approximately 3-4 cases are in boys rather than girls.  This led a lot of the researchers to look at the X-chromosome (of which there is only one in boys). These figures are simply inadequate for denying that an environmental factor being involved as well: for instance the increase that has taken place (see figure from US cases) cannot be explained genetically.   Also it has become clear that twins and second children often do not have similar psychological symptoms of ASD to each other.  The work has been well reviewed but is still showing further genetics that may be involved.

Some genetic changes seem to be reliably associated with ASD but some do not in that some of the genetic changes sometimes have it and in other cases this does not happen.  This is known as non-specific association.  The fact that some genetic modifications are closely associated with a likelihood of ASD has led some researchers to feel that all cases must have some kind of genetic aspect to them.  However, the apparent increase in cases that we seem to have seen of autism over the last 15 years does suggest that either the genes are becoming modified faster than they were before or, because the ASD people uncommonly have many children, a specifically large gene is specifically involved.  An example of this would be to look at cystic fibrosis, where again there is a range of different clinical severities, and about one person in 23 is thought to carry a modified specific gene.  In CF it is because the gene is so large that it is commonly likely to be changed.    It also should be noted that the autism of some genetically associated cases are not psychologically the same as seen in other groups and as such some researchers wonder whether the genetic aspects are a misleading source of information.  

Some elements and genes associated with ASD:

·        15q11-q13 duplication

·        Advanced glycation end product changes

·        Angelman Syndrome

·        Familial clustering

·        Fragile X permutation

·        GABA receptor

·        Glutamate associated

·        Hyperlexia syndrome

·        Many individual genetic modifications, particularly of chromosome 6 (these are not reviewed here but see Muhle et al below).  See non-specific range

·        Mitochondrial modifications

·        Monoamine oxidase A

·        Neurofibromatosis type 1

·        Neuroligin and Neurexin (X-linked)

·        Oxytocin receptor protein

·        Phenylketonurea

·        Prader-Willi syndrome

·        Reelin gene

·        Savant syndrome

·        SCL25A12 gene

·        Smith-Lemi-Opitz Syndrome

·        Tuberous Sclerosis

 


Excellent Scientific Reviews:

This can be looked on in a way as autism being associated with known genetic conditions (e.g. Alpert’s syndrome) or with specific genes and these separate directions gradually meet up (but not yet!)

 

Muhle R, Trentacoste SV, Rapin I.  The genetics of autism.  Pediatrics. 2004 May;113(5):e472-86.. Major Review in 2004. They make it clear that there is no specific gene that will produce the disease reliably but they explain which specific parts are aimed at being involved.  They also are not that impressed that all the ASDs are in fact the same condition (e.g. fragile X ASD is in fact often associated with other changes in the  body like hyperorchidism).  They explain that the association between monozygotic twins is not perfect (93%) and familial changes are difficult to be sure of in that they depend on the way in which the diagnosis is made.  The reason for this is that there is almost certainly an environmental factor as well on which the genetic factor depends to produce the ASD. There are many genetic syndromes associated with autism but only a limited range appear to have useful that may indicate more about autism itself. The full list of syndromes is here but more useful ones are discussed to a greater extent further on: Angelman syndrome, Prader-Willi syndrome, 15q11-q13 duplication, fragile X syndrome, fragile X premutation, deletion of chromosome 2q, XYY syndrome, Smith-Lemli-Opitz syndrome, Apert syndrome, mutations in the ARX gene, De Lange syndrome, Smith-Magenis syndrome, Williams syndrome, Rett syndrome, Noonan syndrome, Down syndrome, velo-cardio-facial syndrome, myotonic dystrophy, Steinert disease, tuberous sclerosis, Duchenne's disease, Timothy syndrome, 10p terminal deletion, Cowden syndrome, 45,X/46,XY mosaicism, Myhre syndrome, Sotos syndrome, Cohen syndrome, Goldenhar syndrome, Joubert syndrome, Lujan-Fryns syndrome, Moebius syndrome, hypomelanosis of Ito, neurofibromatosis type 1, CHARGE syndrome and HEADD syndrome.  (see this article to look up a lot of the specific syndromes that may, or may not have autism as part of them).

 

Szatmari P, Paterson AD et al . Mapping autism risk loci using genetic linkage and chromosomal rearrangements. Nat Genet. 2007 Mar;39(3):319-28. Epub 2007 Feb 18.   This has a very large number of authors and is particularly interested to implicate chromosome 11p12-p13 and neurexins. 

 

Grice DE, Buxbaum JD. The genetics of autism spectrum disorders.  Neuromolecular Med. 2006;8(4):451-60. Review (this article looks very much into the genetic DNA direction rather than the syndrome association of autism. 

 

Burmeister M, McInnis MG, Zöllner S. Psychiatric genetics: progress amid controversy.  Nat Rev Genet. 2008 Jul;9(7):527-40. Review.

 

Mendelsohn NJ, Schaefer GB. Genetic evaluation of autism.  Semin Pediatr Neurol. 2008 Mar;15(1):27-31. Review. (They go into the ways in which this is being investigated)

 

 

Return to Home Page and Top of Page


 

Non-specific associations of a range of genetic conditions:

 

Warren RP, Singh VK, Cole P, Odell JD, Pingree CB, Warren WL, DeWitt CW, McCullough M. Possible association of the extended MHC haplotype B44-SC30-DR4 with autism. Immunogenetics. 1992;36(4):203-7.

 

Warren RP, Yonk J, Burger RW, Odell D, Warren WL. DR-positive T cells in autism: association with decreased plasma levels of the complement C4B protein Neuropsychobiology. 1995;31(2):53-7.

 

Nishimura Y, Martin CL, Vazquez-Lopez A, Spence SJ, Alvarez-Retuerto AI, Sigman M, Steindler C, Pellegrini S, Schanen NC, Warren ST, Geschwind DH. Genome-wide expression profiling of lymphoblastoid cell lines distinguishes different forms of autism and reveals shared pathways. Hum Mol Genet. 2007 Jul 15;16(14):1682-98. Epub 2007 May 21

 

Nishimura K, Nakamura K, Anitha A, et al.  Genetic analyses of the brain-derived neurotrophic factor (BDNF) gene in autism. Biochem Biophys Res Commun. 2007 Apr 27;356(1):200-6. (A protein that is associated with the serotonergic system. They found that alterations in haplotypes were associated with autism)

 

Nakamine A, Ouchanov L, Jiménez P, Manghi ER, Esquivel M, Monge S, Fallas M, Burton BK, Szomju B, Elsea SH, Marshall CR, Scherer SW, McInnes LA. Duplication of 17(p11.2p11.2) in a male child with autism and severe language delay. Am J Med Genet A. 2007

 

Hu VW, Frank BC, Heine S, Lee NH, Quackenbush J. Gene expression profiling of lymphoblastoid cell lines from monozygotic twins discordant in severity of autism reveals differential regulation of neurologically relevant genes. BMC Genomics. 2006 May 18;7:118. (suggesting how the environmental factor is involved)

 

Junaid MA, Kowal D, Barua M, Pullarkat PS, Sklower Brooks S, Pullarkat RK.  Proteomic studies identified a single nucleotide polymorphism in glyoxalase I as autism susceptibility factor.  Am J Med Genet A. 2004 Nov 15;131(1):11-7

 

James SJ, Melnyk S, Jernigan S, Cleves MA, Halsted CH, Wong DH, Cutler P, Bock K, Boris M, Bradstreet JJ, Baker SM, Gaylor DW. Metabolic endophenotype and related genotypes are associated with oxidative stress in children with autism. Am J Med Genet B Neuropsychiatr Genet. 2006 Dec 5;141(8):947-56. (the interesting thing about this one is that they are suggesting that the oxidative stress problem comes first and, as a result the autism is seen…as opposed to the damage coming first and the oxidative stress appearing later)

 

Sahoo T, Shaw CA, Young AS, Whitehouse NL, Schroer RJ, Stevenson RE, Beaudet AL. Array-based comparative genomic mutation in analysis of recurrent chromosome 15q rearrangements. Am J Med Genet A. 2005 Dec 1;139(2):106-13. (15q is associated with GABA receptors.  New (non-published) data is coming out from the Boston area in which a fragment of chromosome 16 is missing or altered in autistic children.

 

Molloy CA, Keddache M, Martin LJ. Evidence for linkage on 21q and 7q in a subset of autism characterized by developmental regression. Mol Psychiatry. 2005 Aug;10(8):741-6.

 

Nishimura K, Nakamura K, Anitha A, Yamada K, Tsujii M, Iwayama Y, Hattori E, Toyota T, Takei N, Miyachi T, Iwata Y, Suzuki K, Matsuzaki H, Kawai M, Sekine Y, Tsuchiya K, Sugihara G, Suda S, Ouchi Y, Sugiyama T, Yoshikawa T, Mori N. Genetic analyses of the brain-derived neurotrophic factor (BDNF) gene in autism. Biochem Biophys Res Commun. 2007 Apr 27;356(1):200-6. Epub 2007

 

Marui T, Funatogawa I, Koishi S, Yamamoto K, Matsumoto H, Hashimoto O, Nanba E, Nishida H, Sugiyama T, Kasai K, Watanabe K, Kano Y, Kato N, Sasaki T. Tachykinin 1 (TAC1) gene SNPs and haplotypes with autism: a case-control study. Brain Dev. 2007 Sep;29(8):510-3. Epub 2007 Mar 21.  (To elucidate the genetic background of autism, we analyzed the relationship between three single nucleotide polymorphisms (SNPs) of the Tachykinin 1 gene (TAC1) and autism, because TAC1 is located in the candidate region for autism and produces substance P and neurokinins. These products modulate glutamatergic excitatory synaptic transmission and are also involved in inflammation. They found that Thus, the TAC1 locus is not likely to play a major role in the development of autism.)

Toyoda T, Nakamura K, Yamada K, Thanseem I, Anitha A, Suda S, Tsujii M, Iwayama Y, Hattori E, Toyota T, Miyachi T, Iwata Y, Suzuki K, Matsuzaki H, Kawai M, Sekine Y, Tsuchiya K, Sugihara G, Ouchi Y, Sugiyama T, Takei N, Yoshikawa T, Mori N. SNP analyses of growth factor genes EGF, TGFbeta-1, and HGF reveal haplotypic association of EGF with autism. Biochem Biophys Res Commun. 2007 Sep 7;360(4):715-20. Epub 2007 Jun 18.   (Epidermal growth factor (EGF) is detected in several regions of the developing and adult brain, where, it enhances the differentiation, maturation, and survival of a variety of neurons. Transforming growth factor-beta (TGFbeta) isoforms play an important role in neuronal survival, and the hepatocyte growth factor (HGF) has been shown to exhibit neurotrophic activity.  They could find no oddities for TGF or HGF genetically but they suggest EGF changes may be involved)

 

Anitha A, Nakamura K, Yamada K, Suda S, Thanseem I, Tsujii M, Iwayama Y, Hattori E, Toyota T, Miyachi T, Iwata Y, Suzuki K, Matsuzaki H, Kawai M, Sekine Y, Tsuchiya K, Sugihara GI, Ouchi Y, Sugiyama T, Koizumi K, Higashida H, Takei N, Yoshikawa T, Mori N. Genetic analyses of Roundabout (ROBO) axon guidance receptors in autism. Am J Med Genet B Neuropsychiatr Genet. 2008 Feb 12. (Abnormalities of ROBO may lead to autism either by interfering with serotonergic system, or by disrupting neurodevelopment. To the best of our knowledge, this is the first report relating ROBO with autism.  This is more of a suggestion than a finding of an answer)

 

Marui T, Koishi S, Funatogawa I, Yamamoto K, Matsumoto H, Hashimoto O, Ishijima M, Nanba E, Nishida H, Sugiyama T, Kasai K, Watanabe K, Kano Y, Kato N, Sasaki T. No association between the neuronal pentraxin II gene polymorphism and autism. Prog Neuropsychopharmacol Biol Psychiatry. 2007 May 9;31(4):940-3.

Ramoz N, Cai G, Reichert JG, Silverman JM, Buxbaum JD. An analysis of candidate autism loci on chromosome 2q24-q33: Evidence for association to the STK39 gene. Am J Med Genet B Neuropsychiatr Genet. 2008 Mar 17. (a quite wide statistical association )

 

Autism Genome Project Consortium, Szatmari P, Paterson AD, Zwaigenbaum L, Roberts W, Brian J, Liu XQ, Vincent JB, Skaug JL, Thompson AP, Senman L, Feuk L, Qian C, Bryson SE, Jones MB, Marshall CR, Scherer SW, Vieland VJ, Bartlett C, Mangin LV, Goedken R, Segre A, Pericak-Vance MA, Cuccaro ML, Gilbert JR, Wright HH, Abramson RK, Betancur C, Bourgeron T, Gillberg C, Leboyer M, Buxbaum JD, Davis KL, Hollander E, Silverman JM, Hallmayer J, Lotspeich L, Sutcliffe JS, Haines JL, Folstein SE, Piven J, Wassink TH, Sheffield V, Geschwind DH, Bucan M, Brown WT, Cantor RM, Constantino JN, Gilliam TC, Herbert M, Lajonchere C, Ledbetter DH, Lese-Martin C, Miller J, Nelson S, Samango-Sprouse CA, Spence S, State M, Tanzi RE, Coon H, Dawson G, Devlin B, Estes A, Flodman P, Klei L, McMahon WM, Minshew N, Munson J, Korvatska E, Rodier PM, Schellenberg GD, Smith M, Spence MA, Stodgell C, Tepper PG, Wijsman EM, Yu CE, Rogé B, Mantoulan C, Wittemeyer K, Poustka A, Felder B, Klauck SM, Schuster C, Poustka F, Bölte S, Feineis-Matthews S, Herbrecht E, Schmötzer G, Tsiantis J, Papanikolaou K, Maestrini E, Bacchelli E, Blasi F, Carone S, Toma C, Van Engeland H, de Jonge M, Kemner C, Koop F, Langemeijer M, Hijmans C, Staal WG, Baird G, Bolton PF, Rutter ML, Weisblatt E, Green J, Aldred C, Wilkinson JA, Pickles A, Le Couteur A, Berney T, McConachie H, Bailey AJ, Francis K, Honeyman G, Hutchinson A, Parr JR, Wallace S, Monaco AP, Barnby G, Kobayashi K, Lamb JA, Sousa I, Sykes N, Cook EH, Guter SJ, Leventhal BL, Salt J, Lord C, Corsello C, Hus V, Weeks DE, Volkmar F, Tauber M, Fombonne E, Shih A, Meyer KJ. Mapping autism risk loci using genetic linkage and chromosomal rearrangements.  Nat Genet. 2007 Mar;39(3):319-28. Epub 2007 Feb 18. (they attempt to show an increase in certain gene loci (or decrease) being associated with autism.  A very difficult process as few other elements of data are used to assess the patients)

 

Buxbaum JD, Cai G, Nygren G, Chaste P, Delorme R, Goldsmith J, Råstam M, Silverman JM, Hollander E, Gillberg C, Leboyer M, Betancur C. Mutation analysis of the NSD1 gene in patients with autism spectrum disorders and macrocephaly. BMC Med Genet. 2007 Nov 14;8:68.

 

Buxbaum JD, Cai G, Chaste P, Nygren G, Goldsmith J, Reichert J, Anckarsäter H, Rastam M, Smith CJ, Silverman JM, Hollander E, Leboyer M, Gillberg C, Verloes A, Betancur C.  Mutation screening of the PTEN gene in patients with autism spectrum disorders and macrocephaly.

Am J Med Genet B Neuropsychiatr Genet. 2007 Jun 5;144B(4):484-91

 

Sakurai T, Ramoz N, Reichert JG, Corwin TE, Kryzak L, Smith CJ, Silverman JM, Hollander E, Buxbaum JD. Association analysis of the NrCAM gene in autism and in subsets of families with severe obsessive-compulsive or self-stimulatory behaviors.

Psychiatr Genet. 2006 Dec;16(6):251-7.

 

Ramoz N, Cai G, Reichert JG, Corwin TE, Kryzak LA, Smith CJ, Silverman JM, Hollander E, Buxbaum JD. Family-based association study of TPH1 and TPH2 polymorphisms in autism. Am J Med Genet B Neuropsychiatr Genet. 2006 Dec 5;141B(8):861-7.

Ramoz N, Reichert JG, Corwin TE, Smith CJ, Silverman JM, Hollander E, Buxbaum JD. Lack of evidence for association of the serotonin transporter gene SLC6A4 with autism. Biol Psychiatry. 2006 Jul 15;60(2):186-91. Epub 2006 Apr 17. see other site on serotonin site

Richler E, Reichert JG, Buxbaum JD, McInnes LA. Autism and ultraconserved non-coding sequence on chromosome 7q. Psychiatr Genet. 2006 Feb;16(1):19-23. (results show that these sequences are unlikely to harbour major autism susceptibility alleles)

 

Faham M, Zheng J, Moorhead M, Fakhrai-Rad H, Namsaraev E, Wong K, Wang Z, Chow SG, Lee L, Suyenaga K, Reichert J, Boudreau A, Eberle J, Bruckner C, Jain M, Karlin-Neumann G, Jones HB, Willis TD, Buxbaum JD, Davis RW. Multiplexed variation scanning for 1,000 amplicons in hundreds of patients using mismatch repair detection (MRD) on tag arrays. Proc Natl Acad Sci U S A. 2005 Oct 11;102(41):14717-22. Epub 2005 Oct 3. (this was showing how the method that they were using would show a difference between specific different amplicons in an autistic patient compared with a control).

 

Buxbaum JD, Silverman J, Keddache M, Smith CJ, Hollander E, Ramoz N, Reichert JG. Linkage analysis for autism in a subset families with obsessive-compulsive behaviors: evidence for an autism susceptibility gene on chromosome 1 and further support for susceptibility genes on chromosome 6 and 19. Mol Psychiatry. 2004 Feb;9(2):144-50. (suggest that there is an autism susceptibility gene on chromosome 1 and provide further support for the presence of autism susceptibility genes on chromosomes 6 and 19)

 

Weiss LA, Escayg A, Kearney JA, Trudeau M, MacDonald BT, Mori M, Reichert J, Buxbaum JD, Meisler MH. Sodium channels SCN1A, SCN2A and SCN3A in familial autism.  Mol Psychiatry. 2003 Feb;8(2):186-94. (The variant R1902C in SCN2A is located in the calmodulin binding site and was found to reduce binding affinity for calcium-bound calmodulin. R542Q in SCN1A was observed in one autism family…just a bit lacking in statistics for autism and further work needs to be carried out)

 

Buxbaum JD, Silverman JM, Smith CJ, Kilifarski M, Reichert J, Hollander E, Lawlor BA, Fitzgerald M, Greenberg DA, Davis KL. Evidence for a susceptibility gene for autism on chromosome 2 and for genetic heterogeneity.  Am J Hum Genet. 2001 Jun;68(6):1514-20. Epub 2001 May 14. Erratum in: Am J Hum Genet 2001 Aug;69(2):470.

 

Bolton PF, Veltman MW, Weisblatt E, Holmes JR, Thomas NS, Youings SA, Thompson RJ, Roberts SE, Dennis NR, Browne CE, Goodson S, Moore V, Brown J. Chromosome 15q11-13 abnormalities and other medical conditions in individuals with autism spectrum disorders.

Psychiatr Genet. 2004 Sep;14(3):131-7.

 

Bacchelli E, Blasi F, Biondolillo M, Lamb JA, Bonora E, Barnby G, Parr J, Beyer KS, Klauck SM, Poustka A, Bailey AJ, Monaco AP, Maestrini E; International Molecular Genetic Study of Autism Consortium (IMGSAC). Screening of nine candidate genes for autism on chromosome 2q reveals rare nonsynonymous variants in the cAMP-GEFII gene. Mol Psychiatry. 2003 Nov;8(11):916-24.

 

Newbury DF, Bonora E, Lamb JA, Fisher SE, Lai CS, Baird G, Jannoun L, Slonims V, Stott CM, Merricks MJ, Bolton PF, Bailey AJ, Monaco AP; International Molecular Genetic Study of Autism Consortium. FOXP2 is not a major susceptibility gene for autism or specific language impairment. Am J Hum Genet. 2002 May;70(5):1318-27. Epub 2002 Mar 13.

International Molecular Genetic Study of Autism Consortium (IMGSAC). A genomewide screen for autism: strong evidence for linkage to chromosomes 2q, 7q, and 16p. Am J Hum Genet. 2001 Sep;69(3):570-81. Epub 2001 Jul 30.  (they have got the money, the time, the laboratory, the methods but it is exceptionally difficult to nail down a specific gene that is the cause.  These were some of the first attempts that they had)

 

International Molecular Genetic Study of Autism Consortium (IMGSAC). Further characterization of the autism susceptibility locus AUTS1 on chromosome 7q. Hum Mol Genet. 2001 Apr 15;10(9):973-82.

Rabionet R, Jaworski JM, Ashley-Koch AE, Martin ER, Sutcliffe JS, Haines JL, Delong GR, Abramson RK, Wright HH, Cuccaro ML, Gilbert JR, Pericak-Vance MA. Analysis of the autism chromosome 2 linkage region: GAD1 and other candidate genes. Neurosci Lett. 2004 Dec 6;372(3):209-14. (they found no association)

Sweeten TL, Odell DW, Odell JD, Torres AR. C4B null alleles are not associated with genetic polymorphisms in the adjacent gene CYP21A2 in autism. BMC Med Genet. 2008 Jan 7;9:1.

 

Chaste P, Nygren G, Anckarsäter H, Råstam M, Coleman M, Leboyer M, Gillberg C, Betancur C. Mutation screening of the ARX gene in patients with autism. Am J Med Genet B Neuropsychiatr Genet. 2007 Mar 5;144B(2):228-30. Mutations in the Aristaless related homeobox (ARX) gene are associated with a broad spectrum of disorders….but they found them to be very uncommon in autism.)

 

Nabi R, Serajee FJ, Chugani DC, Zhong H, Huq AH. Association of tryptophan 2,3 dioxygenase gene polymorphism with autism. Am J Med Genet B Neuropsychiatr Genet. 2004 Feb 15;125B(1):63-8. (Haplotype analysis also demonstrated significant difference in the transmission of TDO2 haplotypes to autistic subjects (P = 0.0027). Our results suggest the presence of a susceptibility mutation in the TDO2 or a nearby gene, but may also represent a chance finding.)

 

Asano E, Kuivaniemi H, Huq AH, Tromp G, Behen M, Rothermel R, Herron J, Chugani DC. A study of novel polymorphisms in the upstream region of vasoactive intestinal peptide receptor type 2 gene in autism.  J Child Neurol. 2001 May;16(5):357-63 (These preliminary results suggest that VIPR2 may have a role in gastrointestinal symptoms and stereotypical behaviors in autism, although they admit that a much larger study would help)

 

Loat C, Curran S, Lewis C, Abrahams B, Duvall J, Geschwind D, Bolton P, Craig I. Methyl - CpG - binding protein (MECP2) polymorphisms and vulnerability to autism.  Genes Brain Behav. 2008 Jun 2.

 

Allan AM, Liang X, Luo Y, Pak C, Li X, Szulwach KE, Chen D, Jin P, Zhao X. The loss of methyl-CpG binding protein 1 leads to autism-like behavioral deficits. Hum Mol Genet. 2008 Jul 1;17(13):2047-57. Epub 2008 Apr 1.

 

Jill James S, Melnyk S, Jernigan S, Hubanks A, Rose S, Gaylor DW. Abnormal Transmethylation/transsulfuration Metabolism and DNA Hypomethylation Among Parents of Children with Autism.  J Autism Dev Disord. 2008 May 30.

 

Kato C, Tochigi M, Koishi S, Kawakubo Y, Yamamoto K, Matsumoto H, Hashimoto O, Kim SY, Watanabe K, Kano Y, Nanba E, Kato N, Sasaki T. Association study of the commonly recognized breakpoints in chromosome 15q11-q13 in Japanese autistic patients. Psychiatr Genet. 2008 Jun;18(3):133-6.

 

Vincent JB, Choufani S, Horike S, Stachowiak B, Li M, Dill FJ, Marshall C, Hrynchak M, Pewsey E, Ukadike KC, Friedman JM, Srivastava AK, Scherer SW. A translocation t(6;7)(p11-p12;q22) associated with autism and mental retardation: localization and identification of candidate genes at the breakpoints. Psychiatr Genet. 2008 Jun;18(3):101-9.

 

Maussion G, Carayol J, Lepagnol-Bestel AM, Tores F, Loe-Mie Y, Milbreta U, Rousseau F, Fontaine K, Renaud J, Moalic JM, Philippi A, Chedotal A, Gorwood P, Ramoz N, Hager J, Simonneau M. Convergent evidence identifying MAP/microtubule affinity-regulating kinase 1 (MARK1) as a susceptibility gene for autism. Hum Mol Genet. 2008 May 20.

 

Bayou N, M'rad R, Belhaj A, Daoud H, Ben Jemaa L, Zemni R, Briault S, Helayem MB, Chaabouni H. De novo balanced translocation t (7;16) (p22.1; p11.2) associated with autistic disorder. J Biomed Biotechnol. 2008;2008:231904.

 

Newmeyer A, deGrauw T, Clark J, Chuck G, Salomons G. Screening of male patients with autism spectrum disorder for creatine transporter deficiency. Neuropediatrics. 2007 Dec;38(6):310-2.

 

Kent L, Emerton J, Bhadravathi V, Weisblatt E, Pasco G, Willatt LR, McMahon R, Yates JR. X linked ichthyosis (steroid sulphatase deficiency) is associated with increased risk of attention deficit hyperactivity disorder, autism and social communication deficits.  J Med Genet. 2008 Apr 15.

 

Gamerdinger U, Eggermann T, Schubert R, Schwanitz G, Kreiss-Nachtsheim M. Rare interstitial deletion 9q31.2 to q33.1 de novo: longitudinal study in a patient over a period of more than 20 years. Am J Med Genet A. 2008 May 1;146A(9):1180-4.

 

Kim SJ, Brune CW, Kistner EO, Christian SL, Courchesne EH, Cox NJ, Cook EH. Transmission disequilibrium testing of the chromosome 15q11-q13 region in autism. Am J Med Genet B Neuropsychiatr Genet. 2008 Mar 24.

 

Wassink TH, Vieland VJ, Sheffield VC, Bartlett CW, Goedken R, Childress D, Piven J. Posterior probability of linkage analysis of autism dataset identifies linkage to chromosome 16. Psychiatr Genet. 2008 Apr;18(2):85-91.

 

Roohi J, Montagna C, Tegay DH, Palmer LE, Devincent C, Pomeroy JC, Christian SL, Nowak N, Hatchwell E. Disruption of Contactin 4 in 3 Subjects with Autism Spectrum Disorder. J Med Genet. 2008 Mar 18.

 

Ramoz N, Cai G, Reichert JG, Silverman JM, Buxbaum JD. An analysis of candidate autism loci on chromosome 2q24-q33: Evidence for association to the STK39 gene. Am J Med Genet B Neuropsychiatr Genet. 2008 Mar 17.

 

Dykens EM, Sutcliffe JS, Levitt P. Autism and 15q11-q13 disorders: behavioral, genetic, and pathophysiological issues. Ment Retard Dev Disabil Res Rev. 2004;10(4):284-91.

 

Nurmi EL, Dowd M, Tadevosyan-Leyfer O, Haines JL, Folstein SE, Sutcliffe JS. Exploratory subsetting of autism families based on savant skills improves evidence of genetic linkage to 15q11-q13. J Am Acad Child Adolesc Psychiatry. 2003 Jul;42(7):856-63

 

 


 

Monoamine oxidase A

 

Cohen IL, Liu X, Schutz C, White BN, Jenkins EC, Brown WT, Holden JJ  Association of autism severity with a monoamine oxidase A functional polymorphism.Clin Genet. 2003 Sep;64(3):190-7.

 

Huang YY, Cate SP, Battistuzzi C, Oquendo MA, Brent D, Mann JJ   An association between a functional polymorphism in the monoamine oxidase a gene promoter, impulsive traits and early abuse experiences  Neuropsychopharmacology. 2004 Aug;29(8):1498-505.  

 

Davis LK, Hazlett HC, Librant AL, Nopoulos P, Sheffield VC, Piven J, Wassink TH. Cortical enlargement in autism is associated with a functional VNTR in the monoamine oxidase A gene. Am J Med Genet B Neuropsychiatr Genet. 2008 Mar 24.  (see MRI scanning concerning brain enlargement. A polymorphism exists within the promoter region of the MAOA gene that influences MAOA expression levels so that "low activity" alleles are associated with increased neurotransmitter levels in the brain. Individuals with autism often exhibit elevated serotonin levels. A consistent association between the "low activity" allele and larger brain volumes for regions of the cortex in children with autism but not in controls. They did not find evidence for over-transmission of the "low activity" allele in a separate sample of 114 affected sib pair families.)

 

Roohi J, Devincent CJ, Hatchwell E, Gadow KD.  Association of a Monoamine Oxidase-A Gene Promoter Polymorphism With ADHD and Anxiety in Boys With Autism Spectrum Disorder.  J Autism Dev Disord. 2008 Jun 20.  

 

Hranilović D, Novak R, Babić M, Novokmet M, Bujas-Petković Z, Jernej B. Hyperserotonemia in autism: the potential role of 5HT-related gene variants. Coll Antropol. 2008 Jan;32 Suppl 1:75-80.  (they looked at the effect of the MAOA gene and others in increasing the serotonin levels of the platelets).

 

 

Return to Home Page and Top of Page


 

GABA receptor

 

Buxbaum JD, Silverman JM, Smith CJ, Greenberg DA, Kilifarski M, Reichert J, Cook EH Jr, Fang Y, Song CY, Vitale R. Association between a GABRB3 polymorphism and autism.  Mol Psychiatry. 2002;7(3):311-6. (gamma-aminobutyric acid type-A receptor beta3 subunit gene (GABRB3) has been associated in one study(2) but not others.(3-5) We completed an association analysis with 155CA-2 using the transmission disequilibrium test (TDT) in a set of 80 autism families (59 multiplex and 21 trios). We also used four additional markers (69CA, 155CA-1, 85CA, and A55CA-1) localized within 150 kb of 155CA-2. The use of multi-allelic TDT (MTDT) (P < 0.002), as well as the TDT (P < 0.004), demonstrated an association between autistic disorder and 155CA-2 in these families. Meiotic segregation distortion could be excluded as a possible cause for these results since no disequilibrium was observed in unaffected siblings. These findings support a role for genetic variants within the GABA receptor gene complex in 15q11-13 in autistic disorder.)

 

McCauley JL, Olson LM, Delahanty R, Amin T, Nurmi EL, Organ EL, Jacobs MM, Folstein SE, Haines JL, Sutcliffe JS.  A linkage disequilibrium map of the 1-Mb 15q12 GABA(A) receptor subunit cluster and association to autism  Am J Med Genet B Neuropsychiatr Genet. 2004 Nov 15;131B(1):51-9 (looked into because of the association with the Prader-Willi/Agelmann syndrome)

 

Return to Home Page and Top of Page


 

Tuberous sclerosis (assn)

(This is a specific uncommon condition that is found to have an excess of autism.  Its help in indicating the background to the disease in the brain is not good.  Click on the Marcotte paper and get some more information on the illness)

 

Marcotte L, Crino PB. The neurobiology of the tuberous sclerosis complex. Neuromolecular Med. 2006;8(4):531-46.

 

Wiznitzer M. Autism and tuberous sclerosis. J Child Neurol. 2004 Sep;19(9):675-9. Review

 

Humphrey A, Neville BG, Clarke A, Bolton PF. Autistic regression associated with seizure onset in an infant with tuberous sclerosis. Dev Med Child Neurol. 2006 Jul;48(7):609-11.

 

Asano E, Chugani DC, Muzik O, Behen M, Janisse J, Rothermel R, Mangner TJ, Chakraborty PK, Chugani HT. Autism in tuberous sclerosis complex is related to both cortical and subcortical dysfunction. Neurology. 2001 Oct 9;57(7):1269-77.

 

 

Return to Home Page and Top of Page


 

Phenylketonurea (assn)

 

Baieli S, Pavone L, Meli C, Fiumara A, Coleman M. Autism and phenylketonurea.  J Autism Dev Disord. 2003 Apr;33(2):201-4.

 

 


 

Smith-Lemli-Opitz syndrome:

a genetic abnormality of the cholesterol manufacturing path (NB all normal steroid hormones like androgens and oestrogens are made from cholesterol in the body. This is one of the groups where the syndrome of autism is noticeably different from the wide range of ASD as seen in other cases)

 

Bukelis I, Porter FD, Zimmerman AW, Tierney E. Smith-Lemli-Opitz syndrome and autism spectrum disorder. Am J Psychiatry. 2007 Nov;164(11):1655-61.

 

Sikora DM, Pettit-Kekel K, Penfield J, Merkens LS, Steiner RD. The near universal presence of autism spectrum disorders in children with Smith-Lemli-Opitz syndrome. Am J Med Genet A. 2006 Jul 15;140(14):1511-8.

 

Return to Home Page and Top of Page


 

Association with Neuroligin and Neurexin

(X-linked, and currently being chased)

 

Feng J, Schroer R, Yan J, Song W, Yang C, Bockholt A, Cook EH Jr, Skinner C, Schwartz CE, Sommer SS. High frequency of neurexin 1beta signal peptide structural variants in patients with autism. Neurosci Lett. 2006 Nov 27;409(1):10-3.

 

Tabuchi K, Blundell J, Etherton MR, Hammer RE, Liu X, Powell CM, Südhof TC. A neuroligin-3 mutation implicated in autism increases inhibitory synaptic transmission in mice. Science. 2007 Oct 5;318(5847):71-6

 

Levinson JN, El-Husseini A. A crystal-clear interaction: relating neuroligin/neurexin complex structure to function at the synapse. Neuron. 2007 Dec 20;56(6):937-9.

 

Yamakawa H, Oyama S, Mitsuhashi H, Sasagawa N, Uchino S, Kohsaka S, Ishiura S. Neuroligins 3 and 4X interact with syntrophin-gamma2, and the interactions are affected by autism-related mutations. Biochem Biophys Res Commun. 2007 Mar 30;355(1):41-6.

 

Talebizadeh Z, Lam DY, Theodoro MF, Bittel DC, Lushington GH, Butler MG. Novel splice isoforms for NLGN3 and NLGN4 with possible implications in autism. J Med Genet. 2006 May;43(5):e21.

 

This attempts to show at which point during the development we see the activity of specific genes

during hard line period leading up to the box with the gene’s name in it. However it may continue past this (dotted line)

to have a period of influence (Pardo and Eberhart 2007)

 

Chen X, Liu H, Shim AH, Focia PJ, He X. Structural basis for synaptic adhesion mediated by neuroligin-neurexin interactions. Nat Struct Mol Biol. 2008 Jan;15(1):50-6. Epub 2007 Dec 16.

 

De Jaco A, Comoletti D, King CC, Taylor P. Trafficking of cholinesterases and neuroligins mutant proteins An association with autism. Chem Biol Interact. 2008 Apr 29.   Recent studies reported that sequence polymorphisms in neuroligin-3 (NLGN3) and neuroligin-4 (NLGN4) genes have been linked to autism spectrum disorders indicating neuroligin genes as candidate targets in brain disorders. They have characterized a single mutation found in two affected brothers that substituted Arg451 to Cys in NL3.  Data show that the exposed Cys causes retention of the protein in the endoplasmic reticulum (ER) when expressed in HEK-293 cells.   Mutations in acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) and found a similar processing deficiency and intracellular retention (De Jaco et al., J Biol Chem. 2006, 281:9667-76). NL3, AChE and BChE mutant proteins are recognized as misfolded in the ER, and degraded via the proteasome pathway.  A 2D electrophoresis coupled with mass spectrometry based approach was used to analyze proteins co-immunoprecipitating with NL3 and show differential expression of factors interacting with wild type and mutant NL3. We identified several proteins belonging to distinct ER resident chaperones families, including calnexin, responsible for playing a role in the folding steps of the AChE and NLs.  The wonder is whether we are looking at changes in protein modification within the ER.

 

Yan J, Noltner K, Feng J, Li W, Schroer R, Skinner C, Zeng W, Schwartz CE, Sommer SS. Neurexin 1alpha structural variants associated with autism. Neurosci Lett. 2008 Jun 27;438(3):368-70. Epub 2008 Apr 25.  (Neurexins are presynaptic membrane cell-adhesion molecules which bind to neuroligins, a family of proteins that are associated with autism. To explore the possibility that structural variants in the neurexin alpha genes predispose to autism, the coding regions and associated splice junctions of the neurexin 1alpha gene were sequenced in 116 Caucasian patients with autism and 192 Caucasian controls. Five ultra-rare structural variants including a predicted splicing mutation were found in patients with autism and absent in 10,000 control alleles.  However one ultra-rare one was found in a control.  Always the difficulty with ultra-rare ones is that you don’t know which ones matter in the body all that much and the one found in the control may have less significance than those in the autistics)

 

Bolliger MF, Pei J, Maxeiner S, Boucard AA, Grishin NV, Südhof TC. Unusually rapid evolution of Neuroligin-4 in mice. Proc Natl Acad Sci U S A. 2008 Apr 29;105(17):6421-6. Epub 2008 Apr 23 (the aim being to look for a genetic model) 

 

 

 

Return to Home Page and Top of Page


 

Glutamate genetic association (also see the mitochondrial changes below)

 

Serajee FJ, Zhong H, Nabi R, Huq AH. The metabotropic glutamate receptor 8 gene at 7q31: partial duplication and possible association with autism. J Med Genet. 2003 Apr;40(4):e42. 

 

Jamain S, Betancur C, Quach H, Philippe A, Fellous M, Giros B, Gillberg C, Leboyer M, Bourgeron T; Paris Autism Research International Sibpair (PARIS) Study. Linkage and association of the glutamate receptor 6 gene with autism. Mol Psychiatry. 2002;7(3):302-10. (they have been finding out that certain mice with autistic type symptoms have altered glutamate receptors and so it was worth looking for this in the human cases)

 

Purcell AE, Jeon OH, Zimmerman AW, Blue ME, Pevsner J.Postmortem brain abnormalities of the glutamate neurotransmitter system in autism.Neurology. 2001 Nov 13;57(9):1618-28.

 

Correia C, Coutinho AM, Diogo L, Grazina M, Marques C, Miguel T, Ataíde A, Almeida J, Borges L, Oliveira C, Oliveira G, Vicente AM. Brief report: High frequency of biochemical markers for mitochondrial dysfunction in autism: no association with the mitochondrial aspartate/glutamate carrier SLC25A12 gene. J Autism Dev Disord. 2006 Nov;36(8):1137-40.

 

Return to Home Page and Top of Page


 

Fragile X.

(this is well investigated and you should look this up separately)

 

Farzin F, Perry H, Hessl D, Loesch D, Cohen J, Bacalman S, Gane L, Tassone F, Hagerman P, Hagerman R.  Autism spectrum disorders and attention-deficit/hyperactivity disorder in boys with the fragile X permutation.  J Dev Behav Pediatr. 2006 Apr;27(2 Suppl):S137-44.  (a good review)

 

Jinorose U, Vasiknanonte P, Limprasert P, Brown WT, Panich V. The frequency of fragile X syndrome among selected patients at Songklanagarind Hospital during 1991-1996, studied by cytogenetic and molecular methods. Southeast Asian J Trop Med Public Health. 1997;28 Suppl 3:69-74.

 

Kelley DJ, Davidson RJ, Elliott JL, Lahvis GP, Yin JC, Bhattacharyya A. The Cyclic AMP Cascade Is Altered in the Fragile X Nervous System. PLoS ONE. 2007 Sep 26;2(9):e931. (increased cyclic AMP is produced by platelets, and other blood cells.  This research was carried out to attempt to find the reason for the increase.  Note that cAMP rise has been found in other forms of autism.

 

Gothelf D, Furfaro JA, Hoeft F, Eckert MA, Hall SS, O'Hara R, Erba HW, Ringel J, Hayashi KM, Patnaik S, Golianu B, Kraemer HC, Thompson PM, Piven J, Reiss AL. Neuroanatomy of fragile X syndrome is associated with aberrant behavior and the fragile X mental retardation protein (FMRP). Ann Neurol. 2008 Jan;63(1):40-51.

 

Hay DA. Fragile X - A challenge to models of the mind and to best clinical practice. Cortex. 2008 Jun;44(6):626-7. Epub 2007 Dec 23.

 

Brodkin ES. Social behavior phenotypes in fragile X syndrome, autism, and the Fmr1 knockout mouse: theoretical comment on McNaughton et al. (2008). Behav Neurosci. 2008 Apr;122(2):483-9. Review.

 

McNaughton CH, Moon J, Strawderman MS, Maclean KN, Evans J, Strupp BJ. Evidence for social anxiety and impaired social cognition in a mouse model of fragile X syndrome.  Behav Neurosci. 2008 Apr;122(2):293-300.

 

Garber KB, Visootsak J, Warren ST. Fragile X syndrome. Eur J Hum Genet. 2008 Jun;16(6):666-72. Epub 2008 Apr 9

 

Gong X, Bacchelli E, Blasi F, Toma C, Betancur C, Chaste P, Delorme R, Durand CM, Fauchereau F, Botros HG, Leboyer M, Mouren-Simeoni MC, Nygren G, Anckarsäter H, Rastam M, Gillberg IC, Gillberg C, Moreno-De-Luca D, Carone S, Nummela I, Rossi M, Battaglia A, Jarvela I, Maestrini E, Bourgeron T; The International Molecular Genetic Study of Autism Consortium (IMGSAC)http://www.well.ox.ac.uk/∼maestrin/iat.html.. Analysis of X chromosome inactivation in autism spectrum disorders. Am J Med Genet B Neuropsychiatr Genet. 2008 Mar 24. (this goes into much more than the fragile X but gives a good indication as to how they fit together)

 

 

Return to Home Page and Top of Page


 

Mitochondrial problems 

(NB the decreased levels of carnotine) both genetic and apparently a dysfunction of the mitochondria that appear normal under electron microscropy.  Some of the work indicates genetic changes in the DNA that is found in mitochondria..but some researchers simply show the mitochondria not working adequately, the reason for which is unclear.   The recent review seems to explain how the mitochondrial modifications may give the changes that we see.  However, this type of explanation has been seen through many other causes of ASD.  See also see the  SCL25A12 gene below.

 

Filipek PA, Juranek J, Smith M, Mays LZ, Ramos ER, Bocian M, Masser-Frye D, Laulhere TM, Modahl C, Spence MA, Gargus JJ. Mitochondrial dysfunction in autistic patients with 15q inverted duplication. Ann Neurol. 2003 Jun;53(6):801-4.

 

Tsao CY, Mendell JR. Autistic disorder in 2 children with mitochondrial disorders. J Child Neurol. 2007 Sep;22(9):1121-3

Correia C, Coutinho AM, Diogo L, Grazina M, Marques C, Miguel T, Ataíde A, Almeida J, Borges L, Oliveira C, Oliveira G, Vicente AM. Brief report: High frequency of biochemical markers for mitochondrial dysfunction in autism: no association with the mitochondrial aspartate/glutamate carrier SLC25A12 gene. J Autism Dev Disord. 2006 Nov;36(8):1137-40.

 

Poling JS, Frye RE, Shoffner J, Zimmerman AW. Developmental regression and mitochondrial dysfunction in a child with autism. J Child Neurol. 2006 Feb;21(2):170-2.  (Suble changes in chemistry, bicarbonate level, reduced cytochrome c in muscle biopsy.  They noticed that the serum creatin kinase level also was abnormally elevated in 47% of 47 autistic patients not known to have mitochondrial problems)

 

Ramoz N, Reichert JG, Smith CJ, Silverman JM, Bespalova IN, Davis KL, Buxbaum JD. Linkage and association of the mitochondrial aspartate/glutamate carrier SLC25A12 gene with autism. Am J Psychiatry. 2004 Apr;161(4):662-9

 

Fillano JJ, Goldenthal MJ, Rhodes CH, Marin-Garcia J.  Mitrochondrial dysfunction in patients with hypotonia, epilepsy autism and developmental delay: HEADD syndrome.  J Child Neurol.  2002;17:435-9.  (They could see modifications under EM of the mitochondria, enzyme alterations, and DNA deletions in mitochondria DNA).

 

Rossignol DA, Bradstreet JJ.  Evidence of mitochondrial dysfunction in autism and implications for treatment.  Biochem and Biotech 2008;4:2008-17.  (Classical mitochondrial diseases occur in a subset of individuals with autism and are usually caused by genetic anomalies or mitochondrial respiratory pathway deficits. However, in many cases of autism, there is evidence of mitochondrial dysfunction (MtD) without the classic features associated with mitochondrial disease. MtD appears to be more common in autism and presents with less severe signs and symptoms. It is not associated with discernable mitochondrial pathology in muscle biopsy specimens despite objective evidence of lowered mitochondrial functioning. Exposure to environmental toxins is the likely etiology for MtD in autism. This demonstrates that although there is a very low prevalence of mitochondrial disease in autism, and hence none out of 20 were seen to have any alterations of mitochondria under EM on muscle biopsy, there were good reasons why the normal looking mitochondria of autism may actually not be working correctly.  This would be expected to show decreased energy metabolism in the  brain using ATP but more using phosphocreatinine, depleted glutathione levels, chronic gastrointestinal problems, seizures, hypotonia, abnormalities in fatty acid oxidation, impairment in beta-oxidation and various other obscure chemical alterations e.g. elevated lacta