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Investigation of Imprinted Chromosomal Regions and Mitochondrial Haplotypes in Autism

Autism is a developmental condition that may impair social development, communication, and may be accompanied by narrow interests and repetitive activity. Twin and family studies demonstrate a genetic contribution to autistic spectrum disorders (ASDs). Although substantial effort is aimed at identifying these susceptibility genes, there is no unequivocal evidence to implicate a particular gene. This study proposed two novel approaches to investigating possible genetic risk factors. First, ASDs are known to occur in a number of disorders which arise from individuals possessing extra genetic material such as chromosomal duplications. The overgrowth condition known as Beckwith Weidemann syndrome (BWS) can occur in individuals who inherit two copies of a part of chromosome 11 from their father. The researcher had found that a number of these BWS individuals also have autism, suggesting that an autism susceptibility gene may be present on chromosome 11, although may only be expressed when inherited from the father. Second, there is evidence from several case reports to suggest that variation in the mitochondrial genome may be associated with autism but the role of the mitochondrial genetic code has not been widely investigated in ASDs. Mitochondria supply cells with sufficient energy for a wide range of cellular processes. Polymorphisms within mitochondrial genes may therefore have functional consequences on cellular functions. This study investigated these mechanisms in 300 autism probands parent trios and 230+ Asperger syndrome trios, as well as a control sample in the mitochondrial studies.