How common are duplications of chromosome 15q among individuals with autistic disorder?
Two studies that included a total of 226 patients with autism found duplications in approximately 3-5% of the patients. [4], [5] Duplications of chromosome 15q11-13 (dup15q) are the most frequently identified chromosome problem in individuals with autism. What causes duplications of chromosome 15q to occur? On chromosome 15, there are repeated regions that share nearly identical DNA sequence. These sequence repeats lead to duplications and copying errors by predisposing misalignment of the paired chromosomes. What do we know about the genes in 15q11-q13? The most commonly duplicated region is gene rich, including genes that are expressed from both paternal and maternal chromosomes as well as genes that are expressed differentially based on parent of origin of the chromosome. Because maternally derived duplications are most often associated with the autism phenotype, the two known maternally expressed genes UBE3A and ATP10A (aka ATP10C) are strong candidates. It is likely that other gen
