At the heterozygous level, large deletions or pointmutations of the SHOX gene have been found in families affected by Leri-Weill dyschondrosteosis (LWD, OMIM 127300), a dominantly inherited skeletal dysplasia with disproportionate short stature owing to mesomelic shortening of the forearm and lower leg and Madelung deformity of the arm. Of the 21 probands meeting the clinical inclusion criteria for LWD, SHOX gene mutations were found in 13 (62% of the total). No significant difference was seen in the rate of mutation detection between familial (11 out of 18) and sporadic cases (two out of three cases). In conclusion, from the available data we assume that SHOX gene mutations are the main cause of LWD, with no positive evidence yet existing of the involvement of other genes in the pathogenesis of the disease.