MATERNAL ORIGIN OF INV DUP(15) CHROMOSOMES IN INFANTILE-AUTISM

Six male patients with infantile autism and an extra inverted duplicat ed chromosome 15[inv dup(15)] were reported in a previous study. These patients had four copies of the chromosome region 15pter-q13, or an i nv dup(l5)(pter->q13; q13->pter). In this new study, DNA from the fami lies of four of the patients were analysed using Southern based RFLPs and microsatellite polymorphisms from the region. In all four cases th e inv dup(15) chromosome was of maternal origin. Furthermore, the data suggests that it originated in the maternal meiotic process rather th an in an early mitosis in the developmental process of the embryo. The extra chromosome contained material from both of the maternally deriv ed 15-chromosomes. Based on the molecular data presented here, a model for the origin of chromosome markers of this type is proposed.