Autosomal recessive limb-girdle and Miyoshi muscular dystrophies in the Netherlands: The clinical and molecular spectrum of 244 patients.

In this retrospective study, we conducted a clinico-genetic analysis of patients with autosomal recessive limb-girdle muscular dystrophy (LGMD) and Miyoshi muscular dystrophy (MMD). Patients were identified at the tertiary referral centre for DNA diagnosis in the Netherlands and included if they carried two mutations in CAPN3, DYSF, SGCG, SGCA, SGCB, SGCD, TRIM32, FKRP or ANO5 gene. DNA was screened by direct sequencing and multiplex ligand-dependent probe amplification (MLPA) analysis. A total of 244 patients was identified; 68 LGMDR1/LGMD2A patients with CAPN3 mutations (28%), 67 sarcoglycanopathy patients (LGMDR3-5/LGMD2C-E) (27%), 64 LGMDR12/LGMD2L and MMD3 patients with ANO5 mutations (26%), 25 LGMDR2/LGMD2B and MMD1 with DYSF mutations (10%), 21 LGMDR9/LGMD2I with FKRP mutations (9%) and one LGMDR8/LGMD2H patient with TRIM32 mutations (<1%). The estimated minimum prevalence of AR-LGMD and MMD in the Netherlands amounted to 14.4 × 10-6 . Thirty-three novel mutations were identified. A wide range in age of onset (0-72 years) and loss of ambulation (5-74 years) was found. Fifteen patients (6%) initially presented with asymptomatic hyperCKemia. Cardiac abnormalities were found in 35 patients (17%). Non-invasive ventilation was started in 34 patients (14%). Both cardiac and respiratory involvement occurs across all subtypes, stressing the need for screening in all included subtypes.

ANO5 mutations in the Dutch limb girdle muscular dystrophy population.

A Dutch cohort of 105 limb girdle muscular dystrophy (LGMD) patients were subject to subsequent genetic investigations. In half the families a causative mutation was found. Recently mutations were identified in ANO5 causing LGMD2L and Miyoshi-like myopathy (MMD3), but could also be found in patients with hyperCKemia only. Therefore, we analysed the index cases of the remaining 31 as yet undiagnosed families from our previously described cohort of LGMD patients for the presence of ANO5 mutations. Detailed history and neurological examination were available for all patients. Serum creatine kinase (CK) activity, skeletal muscle computed tomography (CT) and cardiological investigations were performed. Mutations in ANO5 were found in 16% of the families: 11 index patients and two sibs, eight males and five females. The founder mutation c.191dupA was present in 8 out of 13 patients. Ten different pathogenic mutations were identified of which seven were novel: five missense and two splice site mutations. The age of these patients ranged from 26 to 69 years and the age of onset varied from 21 to 57 years. Symptoms at onset were related to proximal leg weakness. The weakness was slowly progressive. Calf hypertrophy was present in three patients. Males were more severely affected than females. Serum CK activity was highly elevated in the early stage of disease and moderately increased in later stages. Muscle biopsy showed predominantly dystrophic changes. One patient had hypertrophic cardiomyopathy, two others had intraventricular septum thickening.

Local dystrophin restoration with antisense oligonucleotide PRO051.

BACKGROUND: Duchenne's muscular dystrophy is associated with severe, progressive muscle weakness and typically leads to death between the ages of 20 and 35 years. By inducing specific exon skipping during messenger RNA (mRNA) splicing, antisense compounds were recently shown to correct the open reading frame of the DMD gene and thus to restore dystrophin expression in vitro and in animal models in vivo. We explored the safety, adverse-event profile, and local dystrophin-restoring effect of a single, intramuscular dose of an antisense oligonucleotide, PRO051, in patients with this disease. METHODS: Four patients, who were selected on the basis of their mutational status, muscle condition, and positive exon-skipping response to PRO051 in vitro, received a dose of 0.8 mg of PRO051 injected into the tibialis anterior muscle. A biopsy was performed 28 days later. Safety measures, composition of mRNA, and dystrophin expression were assessed. RESULTS: PRO051 injection was not associated with clinically apparent adverse events. Each patient showed specific skipping of exon 51 and sarcolemmal dystrophin in 64 to 97% of myofibers. The amount of dystrophin in total protein extracts ranged from 3 to 12% of that found in the control specimen and from 17 to 35% of that of the control specimen in the quantitative ratio of dystrophin to laminin alpha2. CONCLUSIONS: Intramuscular injection of antisense oligonucleotide PRO051 induced dystrophin synthesis in four patients with Duchenne's muscular dystrophy who had suitable mutations, suggesting that further studies might be feasible.

CAV3 gene mutation analysis in patients with idiopathic hyper-CK-emia.

As caveolin-3 deficiencies may explain persistent hyper-CK-emia, we performed CAV3 gene mutation analysis and immunohistochemistry for caveolin-3 in 31 patients with idiopathic hyper-CK-emia. In 2 of 29 patients who donated blood, variants in the CAV3 gene were detected. Although immunohistochemical analysis strongly suggested that caveolin-3 was properly localized in the muscle tissue of the two affected patients, it may not function normally and could thus explain their persistent hyper-CK-emia. Our findings contribute to the clarification of unexplained persistent hyper-CK-emia, but further research is needed before CAV3 gene mutation analysis becomes part of the routine evaluation of these patients.