X-linked ichthyosis, due to steroid sulphatase deficiency, associated with Kallmann syndrome (hypogonadotropic hypogonadism and anosmia): linkage relationships with Xg and cloned DNA sequences from the distal short arm of the X chromosome.

We report a large Italian pedigree in which five out of six males are affected by a syndrome, following an X-linked inheritance pattern, characterized by ichthyosis, hypogonadotropic hypogonadism, and anosmia. The concurrence of features of X-linked ichthyosis (XLI) with those of Kallmann syndrome, another disease often inherited as an X-linked trait, prompted us to perform biochemical, cytogenetic, and molecular studies in relation to the short arm of the X chromosome (Xp). Steroid sulphatase (STS) activity was found to be completely deficient in all affected members of the family. Prometaphase chromosome analyses of two obligate heterozygous women and one affected male showed normal karyotypes. Xg blood group antigen analysis and molecular studies employing cloned DNA sequences from the distal segment of the Xp (probes RC8, 782, dic56, and M1A), did not provide evidence for deletions or rearrangements of the X chromosome. The linkage analysis showed no crossovers between the disease, Xg, and DXS143, the locus defined by probe dic56, thus suggesting the possibility of a linkage between these two markers of the distal segment of Xp and the X-linked ichthyosis, hypogonadism, and anosmia syndrome.