MOLECULAR CYTOGENETIC ANALYSIS OF A DUPLICATION XP IN A MALE - FURTHER DELINEATION OF A POSSIBLE SEX INFLUENCING REGION ON THE X-CHROMOSOME

We describe a male infant with severe mental retardation and autism wi th a duplication of the short arm of the X chromosome. Chromosome pain ting confirmed the origin of this X duplication. Molecular cytogenetic analysis with fluorescence in situ hybridization (FISH) identified on e copy of the zinc finger protein on the X chromosome (ZFX) and two co pies of the steroid sulfatase gene (STS), further delineating the brea kpoints. Based on cytogenetic and molecular comparisons of cases from the literature of sex-reversal in dup(X),Y patients and our patient, w e suggest that a possible secondary sex-influencing gene involved in t he regulation of sex determination or testis morphogenesis is present at the distal Xp21.1 to p21.2 region.