Muscular dystrophy is an inherited disease with clinical and genetic heterogeneity. Muscle weakness is the primary symptom of these disorders that often leads to disability and death. The overall prevalence for all types of muscular dystrophies worldwide is 19.8-25.1 per 100,000 population. Autosomal recessive types of muscular dystrophies are more common in Iran, likely due to the high rate of consanguineous marriage. We aimed at deciphering molecular defects in three unrelated families with muscular dystrophies not related to Duchene muscular dystrophy (MD) or limb girdle muscular dystrophies. We are reporting families having affected children with MD owing to the mutations in three genes related to the COL6A (collagen type VI, alpha subunit) gene family. Three unrelated families, who had at least one member affected with MD and for whom a definite molecular diagnosis was not provided by routine methods, were investigated by WES and confirmed by Sanger sequencing. In the first family, a homozygous variant was found in the COL6A3 gene (NM_004369.4:c.4390C>T:p.Arg1464Ter), which explains the clinical symptoms observed in this family. In the second family, two homozygote missense variants with possible relevance to the patient’s phenotype were identified in COL6A1 and COL6A2 genes (NM_001848.2:c.803A>G: p.Glu268Gly and NM_001849.3:c.2489G>A:p.Arg830Gln). Also, a heterozygous pathogenic variant in the COL6A2 gene (NM_001849.3: c.1053+1G>T) was detected in the third family. WES can serve as an effective method for detecting the causative mutations in families with unresolved cases of MD. The data provided herein broadens the spectrum of mutations causing MD in Iran.

Dysferlinopathy is a rare group of hereditary muscular dystrophy with an autosomal recessive mode of inheritance caused by a mutation in the DYSF gene. It encodes for the dysferlin protein, which has a crucial role in multiple cellular processes, including muscle fiber membrane repair. This deficit has heterogeneous clinical presentations. In this study, we collected 20 Tunisian patients with a sex ratio of 1 and a median age of 50.5 years old (Interquartile range (IQR) = [36,5-54,75]). They were followed for periods ranging from 5 to 48 years. The median age at onset was 17 years old (IQR = [16,8-28,4]). Five major phenotypes were identified: Limb-girdle muscular dystrophy (LGMDR2) (35%), a proximodistal phenotype (35%), Miyoshi myopathy (10%),  Distal myopathy with anterior tibial onset (DMAT) (10%), and asymptomatic HyperCKemia (10%). At the last evaluation, more than half of patients (55%) were on wheelchair. Loss of ambulation occurred generally during the fourth decade. After 20 years of disease progression, two patients with a proximodistal phenotype (10%) developed dilated cardiomyopathy and mitral valve regurgitation. Restrictive respiratory syndrome was observed in three patients (DMAT: 1 patient, proximodistal phenotype: 1 patient, LGMDR2: 1 patient). Genetic study disclosed five mutations. We observed clinical heterogeneity between families and even within the same family. Disease progression was mainly slow to intermediate regardless of the phenotype.

Mutations in TCAP gene cause autosomal recessive limb-girdle muscular dystrophy type 2G (LGMD2G), congenital muscular dystrophy and autosomal dominant dilated and hypertrophic cardiomyopathy. We studied 18 affected individuals from 12 pedigrees, belonging to a Bulgarian Muslim minority from the South-West of Bulgaria, homozygous for the c.75G>A, p.Trp25X mutation in TCAP gene. The heterozygous carrier rate of p.Trp25X among 100 newborns in this region was found to be 2%. The clinical features in the Bulgarian TCAP group include disease onset in the first to the third decade of life, proximal muscle weakness in the lower limbs, followed or accompanied by difficulties in ankle dorsiflexion and involvement of the proximal muscles of the upper limbs 5-9 years after the disease onset. Asymmetry between left and right was present in more than 20% of the affected. Respiratory and cardiac functions were not affected. On the MRI the muscles of the posterior pelvic area, thigh and anterior leg were predominantly affected, while sartorius, gracilis and biceps femoris muscles remained relatively spared. In conclusion, LGMD2G appears to be a common form among Bulgarian Muslims. Homozygosity for c.75G>A, p.Trp25X is associated with a homogeneous clinical presentation, but the clinical course and severity of the disease show inter- and intra-familial variation.

Sarcoglycanopathies (SGCs) which are caused by mutations in SGCA, SGCB, SGCG or SGCD genes are a subgroup of autosomal-recessive limb-girdle-muscular-dystrophies (LGMD2). Although frequencies of mutations in these genes are different among populations, mutations in SGCA and SGCD, respectively, have the highest and lowest frequencies in most populations. Here, we report the proportion of mutations in SGC genes among a group of Iranian SGCs patients. Clinical features and results of SGC genes screening of 25 SGCs probands are presented. Large deletion mutations are confirmed with MLPA assays. In total, 15 candidate disease causing mutations were observed in the SGCA, SGCB, SGCG and SGCD genes; ten were novel. Fourteen (56%), seven (28%), three (12%) and one (4%) patient, respectively, carried mutations in SGCB, SGCG, SGCD and SGCA. The findings suggest that LGMD2E is the most common form of SGCs in the Iranian population and that LGMD2D is the rarest. Twelve LGMD2E cases carried the same mutation. To the best of knowledge, the mutation spectrum in SGCs is being reported for the first time in Iranian population. The finding will be beneficial for screening and genetic-counseling of SGCs patients in Iran.

Muscular dystrophy caused by LAMA2-gene mutations is an autosomal recessive disease typically presenting as a severe, early-onset congenital muscular dystrophy (CMD). However, milder cases with a limb-girdle type muscular dystrophy (LGMD) have been described. In this study, we assessed the frequency and phenotypic spectrum of LAMA2-related muscular dystrophy in CMD (n = 18) and LGMD2 (n = 128) cohorts identified in the last 15 years in eastern Denmark. The medical history, brain-MRI, muscle pathology, muscle laminin-α2 expression, and genetic analyses were assessed. Molecular genetics revealed 2 pathogenic LAMA2 mutations in 5 of 18 CMD and 3 of 128 LGMD patients, corresponding to a LAMA2-mutation frequency of 28% in the CMD and 2.3% in the LGMD cohorts, respectively. This study demonstrates a wide clinical spectrum of LAMA2-related muscular dystrophy and its prevalence in an LGMD2 cohort, which indicates that LAMA2 muscular dystrophy should be included in the LGMD2 nomenclature.