The region on 9p associated with 46,XY sex reversal contains several transcripts expressed in the urogenital system and a novel doublesex-related domain

Deletions of 9p have been associated with 46,XY gonadal dysgenesis, and the smallest region of overlap has been mapped to the tip of chromosome 9, Two candidate genes (DMRT1 and 2) have been found in the region, Despite inten sive mutation searches, no mutations have been detected in these genes, To gain insights into the genomics of the region and to isolate other candidat e genes for the phenotype, we have constructed a P1 artificial chromosome ( PAC)/bacterial artificial chromosome (BAC) contig spanning over 500 kb and covering the consensus critical region, We have analyzed the expression pat tern of several ESTs mapped or sublocalized within the framework of the con tig. In addition, a sample shotgun sequencing of a PAC containing the menti oned DM genes led to the detection of novel transcripts displaying an expre ssion pattern specific to testis and kidney, consistent with a role in the development of the urogenital system. One of them, expressed in adult testi s and human embryos aged 4-5 weeks, encodes a potential polypeptide and is located immediately downstream of a sequence capable of encoding a novel DM domain, The region was partially screened for mutations in sex-reversed pa tients by Southern blot, sequencing, and FISH. No mutations were found. Our results suggest that the critical region on 9p involved in male-to-female sex reversal displays greater gene density and genomic complexity than prev iously anticipated. Future investigations will include functional and mutat ional studies of the novel transcripts mapped or sublocalized within the cr itical region by this study as well as cloning efforts to isolate additiona l candidate genes, (C) 2000 Academic Press.