DELETION ANALYSIS MAPS OCULAR ALBINISM PROXIMAL TO THE STEROID SULFATASE LOCUS

We describe a pedigree in which four male members are affected by a co ntiguous gene abnormality involving the short arm of the X chromosome (Xp22.32). Bivariate flow cytometry of lymphoblastoid cell lines from two of these individuals and a normal male showed a 6-7 megabase delet ion in affected males, and high resolution chromosomal G-banding of an obligate heterozygote showed the deletion to reside in the Xp22.32 re gion. Affected members had X-linked ichthyosis due to steroid sulphata se deficiency, Kallmann's syndrome, but no ocular albinism. In two out of four affected individuals studied, there was unilateral renal agen esis. Deletion analysis using the Xp22.32 markers MIC2, DXS31, DXS 89, GMGX9, DXS278, DXS143, and DXS9 showed that the deletion extended fro m DXS31 to DXS143 (inclusive). The absence of ocular albinism in this pedigree shows conclusively that the X-linked ocular albinism gene res ides proximal to the DXS143 locus. Further, the inconstant association of unilateral renal agenesis with X-linked Kallmann's syndrome, even when the latter is caused by a complete deletion of the gene, suggests that the absence of the X-linked Kallmann gene can be compensated in renal development.