CALPAIN-3 DEFICIENCY CAUSES A MILD MUSCULAR-DYSTROPHY IN CHILDHOOD

Among our 20 families with LGMD2, 10 were documented to have muscle-sp ecific calcium-activated neutral protease 3 (calpain-3) deficiency. Co nsanguinity was present in all. The current ages of the index cases we re between 12 and 23 years, and there were additional nine members aff ected. Clinically, the patients showed mild courses; none of the cases below age 30 lost autonomy so far. The dystrophy is mainly proximal a nd atrophic with calf enlargement and scapular wasting in some. In thr ee cases walking was delayed. Creatine kinase levels were at least 10 times elevated. All obligate carriers had normal creatine kinase level s. Five families shared the same 551delA frameshift mutation. In four of these families there was the same core haplotype, whereas one was d istinct suggesting an independent origin. Calpain-3 deficiency in gene ral is a mild muscular dystrophy during childhood.