自閉症・注意欠陥多動障害遺伝子解析

Genetics of autism and ADHD

　自閉性障害の発症には，多くの遺伝子が関与しており，epigeneticsな要因も大きいと考えられている。病因遺伝子同定研究として，連鎖解析，関連疾患の遺伝子解析，候補遺伝子解析が行われているが，多くの患者での病因は不明である。連鎖解析等より，7q，15qなど，いくつかの有望な領域が挙げられている。候補遺伝子として，epigeneticsに関連する遺伝子，扁桃体，海馬，小脳に発現している遺伝子，神経突起伸長，シナプス形成と機能に関与する遺伝子群が，主に解析されている。注意欠陥多動障害は，ドーパミン，カテコールアミンに関連した遺伝子を中心に解析され，DRD4の多型との関連が強く示唆されている。

　We reviewed about the gene analysis for autistic disorder and ADHD. For autistic disorder, many genes are analyzed as candidate genes, but responsible genes for many patients were not identified. Linkage analysis detected many candidate locus, where 7q and 15q are most interesting lesion. To reduce the heterogeneity of autism, quantitative trait loci analysis were done on linkage analsis. The genes relating to epigenetics and genes expressed in amygdala, hyppocampus and cerebellum are good candidate genes. Addition to that, several genes relating to synaps formation and function, such as neuroligin, FMRP, 5-HTT transporter, glutamate and metabotrophic glutamate receptor, were suggested to relate autism. Further analysis will be done for genes acting on synaps. For ADHD, many genes relating to dopamine and cathecolamine metabolism were analyzed. Among them, seven repeat allele of VNTR on DRD4 gene were detected to related to ADHD. Further analysis is required for the relation with genotype and phenotype including drug responsiveness.