A case of syndromic X-linked ichthyosis with Léri-Weill dyschondrosteosis

Abstract

Léri-Weill dyschondrosteosis (LWD) is a skeletal dysplasia marked by disproportionate short stature and characteristic Madelung wrist deformity, which is an epiphyseal growth plate disturbance characterized by dorsal and radial bowing of the radius. In approximately 70% of cases, LWD is caused by haploinsufficiency of the short stature homeobox (SHOX) gene, which maps to the pseudoautosomal region 1 (PAR1) of the sexual chromosomes (Xp22.33 and Yp11.32). Haploinsufficiency results from heterozygous mutations and deletions of SHOX or the downstream PAR1 (where SHOX enhancer elements are located). The molecular defect remains unknown in the other 30% of LWD cases. X-linked ichthyosis (XLI) is the second most common type of ichthyosis, with a prevalence of 1/6,000. The condition is an X-linked recessive disorder of cutaneous keratinization caused by a deficiency in steroid sulfatase (STS) activity. STS is thought to play a role in active cutaneous steroid production and lipid regulation. The gene coding for STS has been mapped to the short arm of the X chromosome at Xp22.3. When accompanied by associated manifestations, such as testicular maldescent, XLI is regarded as syndromic. We report here a case of a 16-year-old French male who sought dermatology consultation for xerosis and skin with a dirty appearance. He benefited from growth hormone for LWD due to SHOX haploinsufficiency. We diagnosed ichthyosis due to STS deficiency in this patient. A contiguous gene deletion syndrome involving SHOX and STS was suspected. Contiguous genes syndromes manifest complex phenotypes that result from the co-deletion of adjacent genes.