Detection of deletions of the SHOX gene in patients with LWD, ISS and Turner Syndrome

Abstract

Deletions and point mutations of the SHOX gene, a homeobox gene located at the pseudoautosomal region of the X and Y chromosome, have been implicated in three human growth disorders: Turner syndrome, Léri-Weill dyschondrosteosis (LWD) and idiopathic short stature (ISS). More than 60% of LWD patients were found to be heterozygous for deletions or point mutations of the SHOX gene whereas the loss of an X chromosome causes at least in part the growth failure in Turner Syndrome. 80% of the mutations found in LWD patients are deletions and the remaining 20% are point mutations. Recent studies have shown that SHOX mutations also account for about 2–7% of idiopathic short stature. Point Mutations and small deletions can be detected by single strand conformation polymorphism (SSCP) analysis or direct sequencing. Fluorescent In Situ Hybridization (FISH) or the analysis of intragenic microsatellite markers can be used to detect larger deletions or deletions of the entire gene. However, deletions of single exons will usually not be detected by FISH and heterozygous deletions of a single exon can't be detected by direct sequencing due to the presence of a second gene copy. We report the detection of complete and partial SHOX deletions with the recently developed multiplex ligation-dependent probe amplification (MLPA) technique (MRC-Holland) in patients with Turner Syndrome, LWD and idiopathic short stature. We analyzed 20 patients (2 patients with Turner Syndrome, 3 with LWD and 15 with ISS) and found a heterozygous deletion of the entire gene in the two patients with Turner Syndrome, the three patients with LWD and in three patients with ISS. As a results of our study we conclude that MLPA is an effective method for the detection of deletions in the SHOX gene.