Les aspects génétiques des gamma-sarcoglycanopathies ou LGMD2C de l’Est Algérien

Abstract

Limb-girdle muscular dystrophy type 2C (LGMD2C) is described as one of the severe forms of childhood-onset muscular dystrophy, it manifests mainly by a deficiency and atrophy of the pelvic and scapular muscles, it is caused by deficiency in the Ɣ-sarcoglycan protein. The distribution of founder mutation c.525delT of SGCG gene in the North of Africa has a prominent effect on the prevalence of the LGMD2C in these populations. It is also known that the LGMD2C resembles clinically to the dystrophinopathies which are the most common muscular dystrophies, the genetic analysis is essential to differentiate the two forms. We report a clinical and genetic study of a large series of 76 Algerian patients from 65 unrelated families from eastern Algeria who presented with a recessive limb-girdle muscular dystrophy (LGMD R). The objectives of the study was to report the clinical and genetic characteristics of patients with LGMD2C observed in East of Algeria and to develop a strategy of molecular diagnosis adapted to our population of patients with LGMD R. We first searched for c.525delT mutation in all the patients with LGMD R. Then, we analyzed the DMD gene in those families that only boys were affected and negative for c.525delT mutation. Finally we completed the analysis of the all SGCG gene. Nineteen patients (25%) were shown to carry SGCG mutations. Only 2 causative mutations were identified in the population, mostly at the homozygous state: the wellknown c.525delT and the c.87dupT never described in North of Africa. The clinical presentation of these patients was very similar regardless of the genotype. We further analyzed the negative families, for the DMD gene and identified 26% (20 patients) of dystrophinopathies with 12 distinctive patterns of deletion were identified with a majority affecting the central region of dystrophin. Our data suggest that a very simple molecular screening consisting of 2 allele-specific PCR and a multiplex PCR can diagnose half of the patients with LGMD R in the East of Algeria.