Presented here are five members of a family that was ascertained from an isolated, consanguineous, indigenous Amerindian community in Colombia that was affected with calpain 3-related, limb-girdle muscular dystrophy type R1. These patients are homozygous for a unique and novel deletion of four bases (TGCC) in exon 3 of the calpain 3 gene (CAPN3) (NM_000070.2; NP_000061.1) (g.409_412del). The mutation site occurs at the CysPc protein domain, triggering a modified truncated protein structure and affecting motifs within the calpain-like thiol protease family (peptidase family C2) region. The patients reported here developed a very severe phenotype with primary contractures, spinal rigidity in the early stages of the disease, and bilateral talipes equinovarus (clubfoot) in the most affected patients who had the selective involvement of their extremities' distal muscles in a way that resembled Emery-Dreifuss syndrome. We recommend mandatory screening for calpainopathy in all patients with an Emery-Dreifuss-like syndrome or those presenting a non-congenital illness with primary contractures and who, because of other data, are suspected of having muscular dystrophy.
Keywords: Amerindian populations; Emery–Dreifuss-like syndrome; calpain 3-related, limb-girdle muscular dystrophy type r1; calpain gene; calpainopathy; clinical presentation; deletion; founder effect; novel mutation.