The frequency of Kallmann syndrome (hypogonadotropic hypogonadism and anosmia, HHA) was estimated in patients presenting with hypogonadism and patients with anosmia.Of 791 hypogonadal males 19 had HHA.
Several loci, including the gene encoding steroid sulfatase (STS) and the loci for the X-linked recessive form of chondrodysplasia punctata (CDPX) and for Kallmann syndrome (KAL) have been placed relative to the Xp telomere.
Also, possible locations for the Kallmann syndrome gene were revealed, and the distance between the steroid sulfatase locus and the pseudoautosomal region was estimated to be at least 4 Mb.
We show here that KAL consists of 14 exons spanning 120-200 kilobases that correlate with the distribution of domains in the predicted protein including four fibronectin type III repeats.
The sequence divergence between KAL and KALP in humans, and the chromosomal location of KAL homologous sequences in other primates, suggest that KALP and the steroid sulphatase pseudogene on Yq11 were involved in the same rearrangement event on the Y chromosome during primate evolution.
The gene responsible for the X-linked KS has been localized to the terminal part of the X-chromosome short arm (Xp22.3 region), immediately proximal to the steroid sulfatase gene responsible for X-linked ichthyosis.