Two male patients with ring Y: definition of an interval in Yq contributing to Turner syndrome

Turner syndrome is thought to result from the haploinsufficiency of genes o n the sex chromosomes, but these genes have not been identified yet. We des cribe two males with deleted ring Y chromosomes, one (TS) with full Turner syndrome and one (DM) without. TS has short stature, skeletal anomalies, ly mphogenic obstruction, cardiovascular abnormalities, and miscellaneous feat ures including pigmented naevi, antimongoloid slanting of the palpebral fis sures, and widely spaced nipples. In contrast, DM has short stature but no other specific Turner stigmata except high arched palate and a few pigmente d naevi. Since Little chromosomal mosaicism was detected, the different seg ments of the Y chromosome retained by these two males identify the location of one or more "anti-Turner" genes. Most of the Yp pseudoautosomal region and Yq were deleted from both patients during the formation of the ring chr omosome, while the Y specific portion of Yp and the centromere were retaine d. The major difference detected was an interval of proximal Yq present in DM and deleted in TS. None of the previously identified genes, DFFRY, DBY, UTY, or TB4Y, lies entirely within this interval, although DFFRY was trunca ted by DM's breakpoint. These data suggest that one or more additional "ant i-Turner" gene(s) remains to be identified in the region of Yq proximal to DFFRY.