Calpain-3 mutations in Turkey

Abstract

Autosomal recessive limb-girdle muscular dystrophies (LGMD2s) are a clinically and genetically heterogeneous group of disorders, characterized by progressive involvement of the proximal limb girdle muscles; the group includes at least 10 different genetic entities. The calpainopathies (LGMD2A), a subgroup of LGMD2s, are estimated to be the most common forms of LGMD2 in all populations so far investigated. LGMD2A is usually characterized by symmetrical and selective atrophy of pelvic, scapular and trunk muscles and a moderate to gross elevation of serum CK. However, the course is highly variable. It is caused by mutations in the CAPN3 gene, which encodes for the calpain-3 protein. Until now, 161 pathogenic mutations have been found in the CAPN3 gene. In the present study, through screening of 93 unrelated LGMD2 families, we identified 29 families with LGMD2A, 21 (22.6%) of which were identified as having CAPN3 gene mutations. We detected six novel (p.K211N, p.D230G, p.Y322H, p.R698S, p.Q738X, c.2257delGinsAA) and nine previously reported mutations (c.550delA, c.19_23del, c.1746-20C>G, p.R49H, p.R490Q, p.Y336N, p.A702V, p.Y537X, p.R541Q) in the CAPN3 gene. There may be a wide variety of mutations, but clustering of specific mutations (c.550delA: 40%, p.R490Q: 10%) could be used in the diagnostic scheme in Turkey.