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Cortical enlargement in autism is associated with a functional VNTR in the monoamine oxidase A gene
Author(s) -
Davis Lea K.,
Hazlett Heather C.,
Librant Amy L.,
Nopoulos Peggy,
Sheffield Val C.,
Piven Joesph,
Wassink Thomas H.
Publication year - 2008
Publication title -
american journal of medical genetics part b: neuropsychiatric genetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.393
H-Index - 126
eISSN - 1552-485X
pISSN - 1552-4841
DOI - 10.1002/ajmg.b.30738
Subject(s) - monoamine oxidase a , autism , allele , serotonin , proband , monoamine oxidase , monoamine neurotransmitter , dopamine , genotype , medicine , psychology , biology , endocrinology , genetics , neuroscience , psychiatry , gene , mutation , biochemistry , receptor , enzyme
Monoamine oxidase A ( MAOA ) is an enzyme expressed in the brain that metabolizes dopamine, norepinephrine, epinephrine, and serotonin. Abnormalities of serotonin neurotransmission have long been implicated in the psychopathology of autism. 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. Additional studies indicate that the “low activity” allele may be associated with lower IQ and more severe autistic symptoms. In this study we genotyped the MAOA promoter polymorphism in a group of 29 males (age 2–3 years) with autism and a group of 39 healthy pediatric controls for whom brain MRI data was available. We found 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. We did not find evidence for over‐transmission of the “low activity” allele in a separate sample of 114 affected sib pair families. Nor did we find any unknown SNPs in yet another sample of 96 probands. Future studies will determine if there is a more severe clinical phenotype associated with both the “low activity” genotype and the larger brain volumes in our sample. © 2008 Wiley‐Liss, Inc.