OBJECTIVE: Chromosome 15q11-q13 has been proposed to harbor a gene for autism susceptibility because deletions of the region lead to Prader-Willi syndrome and Angelman syndrome, whose phenotypes overlap with autism. These deletions generally occur with the use of three commonly recognized breakpoints (BP1, BP2, and BP3); therefore, it may be possible that genes located in the breakpoints are impaired and contribute to autism susceptibility. No study, however, has investigated the genetic association between the breakpoints and autism, to our knowledge. Here, we investigated the association between the common breakpoints of chromosome 15q11-q13 and autism in a Japanese population.
METHODS: We genotyped 12 single nucleotide polymorphisms (SNPs) in 166 patients with autistic disorder and 415 healthy controls. The SNPs are located in two additional distal breakpoints (BP4 and BP5), involved in duplications and triplications of the region, as well as in BP1 and BP3.
RESULTS: No significant difference was observed between the controls and patients in allelic frequencies or genotypic distributions of the 12 SNPs. In the analyses of the suggested five haplotypes, no significant difference between the controls and patients was observed in the distributions of any estimated haplotypes. When confining the patients to only males, a difference was observed in a two-marker haplotype in BP3 between the controls and patients (global permutation P value=0.006), although the statistical level became insignificant after correction for multiple testing.
CONCLUSIONS: This study provides no positive evidence of the association between the common breakpoints of chromosome 15q11-q13 and autism in the Japanese population.

7B2 is a highly conserved protein present in many secretory cells. Using in situ hybridization techniques and immunocytochemistry, parameters concerning the biosynthesis and storage of the 7B2 protein were studied in the pituitary gland and median eminence of the clawed toad Xenopus laevis, in relation to the physiological process of background adaptation. 7B2-like immunoreactivity was present in the median eminence, in the neural and anterior pituitary lobes and, particularly, in the melanotrope cells of the intermediate pituitary lobe. In these cells, it coexisted with immunoreactivity to proopiomelanocortin (POMC)-derived alpha-melanocyte stimulating hormone (alpha MSH). The melanotropes of black-adapted animals had abundant 7B2-mRNA and POMC-mRNA; melanotropes of white-adapted toads had only low levels of these mRNAs. The presence of 7B2 in nerve terminals and endocrine cells supports the idea that the protein has a general function in the cellular secretory process. In X. laevis, 7B2 appears to be particularly associated with POMC and alpha MSH and, therefore, may play a role in the regulation of background adaptation.