ITGB5 mutation discovered in a Chinese family with blepharophimosis-ptosis-epicanthus inversus syndrome.

Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) is a rare autosomal-dominant genetic disorder, and mutations in the forkhead box L2 (FOXL2) gene are one of the major genetic causes. As this study shows, there are many patients with BPES who do not have FOXL2 mutations, as the screening results in all family members were negative. Using whole-exome sequence analysis, we discovered another possible mutational cause of BPES in integrin subunit beta 5 (ITGB5). The ITGB5 mutation (c.608T>C, p.Ile203Thr) appears in the base sequence of all BPES+ patients in this family, and it appears to be a three-generation-inherited mutation. It can cause changes in base sequence and protein function, and there may be cosegregation of disease phenotypes. ITGB5 is located on the long arm of chromosome three (3q21.2) and is close to the known pathogenic gene FOXL2 (3q23). This study is the first to report ITGB5 mutations in BPES, and we speculate that it may be directly involved in the pathogenesis of BPES or indirectly through the regulation of FOXL2.