Causes of SHOX Gene Mutation
SHOX gene mutations can be of several different types, including point mutations, as well as deletions of various sizes. In Turner syndrome, the cause is deletion of not only the SHOX gene, but the absence of an entire X chromosome. This condition therefore causes other symptoms in addition to delayed or absent growth development, due to the absence of other genes.
In familial Leri-Weill dyschondrosteosis, both point mutations and deletions have been found in family groups. These include large deletions of multiple exons (coding regions) in the SHOX gene, as well as small deletions in a single exon. As well, several types of point mutation, including frameshift and missense mutations, have been noted (Falcinelli et. al.). It should be noted that not all instances of this disorder in family groups are caused by SHOX gene mutation. In one study, mutations of the gene were found in only 62% of the families studied (Falcinelli et. al.).
SHOX gene mutations are relatively common in certain short stature genetic disorders of familial origin, and are also a cause of a small percentage of cases of idiopathic short stature (idiopathic short stature conditions are those with no known cause). In one study of 900 children with idiopathic short stature, SHOX gene mutations were detected in only 2.4% of cases. (Gudrun et. al.) The same study found that deletion was the most common mutation leading to short stature disorder.