Pseudoautosomal inheritance of Léri-Weill syndrome: what does it mean?

The short stature homeobox (SHOX) gene is located in the pseudoautosomal region 1 of both sex chromosomes. Haploinsufficiency of SHOX leads to different phenotypes ranging from isolated short stature to Léri-Weill syndrome characterized by short stature, mesomelia and Madelung deformity. We describe a family with a SHOX deletion originally located on the Y chromosome and transmitted from father to daughter by crossover during meiosis. The male index patient presented with short stature, mesomelia and mild Madelung deformity. His father had a normal height but slightly disproportionate short legs. The sister of the index patient presented with marked Madelung deformity and normal height. A deletion of the SHOX gene was identified in the male index patient, his father and his sister. Metaphase fluorescence in situ hybridization (FISH) analyses showed a deletion of the SHOX gene on the Y chromosomes of the index patient and his father, and on the X chromosome of his sister, indicating that a meiotic crossover of the SHOX gene region between the X and Y chromosomes had occurred. The pseudoautosomal region 1 is a known recombination 'hot spot' in male meiosis. Published genetic maps indicate high recombination frequency of ∼40% for SHOX in male meiosis leading to pseudoautosomal inheritance.