Centronuclear Myopathy 2

BIN1-related centronuclear myopathy 2 is a muscle disease affecting type 2 muscle fibers.

Symptoms

Centronuclear myopathies are characterized by muscle weakness, exercise intolerance, muscle atrophy, predominance of type 1 muscle fibers and aberrant positioning of nuclei and mitochondria. The first symptoms usually appear between 6 and 8 months of age and worsen with the course of the disease producing severe muscle weakness.

Disease Management

Available treatments focus on alleviating symptoms. Euthanasia is often resorted to as severe muscle weakening occurs. Should your dog show any symptoms, you should see your veterinarian for evaluation.

Genetic basis

This disease follows an autosomal recessive mode of inheritance. Autosomal recessive inheritance means that the dog, regardless of sex, must receive two copies of the mutation or pathogenic variant to be at risk of developing the disease. Both parents of an affected dog must carry at least one copy of the mutation. Animals with only one copy of the mutation are not at increased risk of developing the disease, but may pass the mutation on to future generations. Breeding between dogs carrying genetic variants that can cause disease, even if they do not show symptoms, is not recommended.

Technical report

The BIN1 gene encodes for the amphiphysin 2 protein, which is involved in intracellular membrane trafficking and membrane remodeling in different cell types. In muscle, it may be involved in the formation of T-tubules (transverse tubules), which are invaginations of muscle cell membranes or sarcolemma, and which are regularly arranged between the myofibrils of striated muscle. Mutations in BIN1 have been associated with two different muscle disorders: centronuclear myopathy and myotonic dystrophy. However, the specific muscle function of amphiphysin 2 and the pathological mechanisms underlying the muscle disorders are not well understood. In the study of Böhm et al. it was shown that the c.786-2A>G mutation in the BIN1 gene can cause centronuclear myopathy in Great Danes.

Most affected breeds

Great Dane

Bibliography

Böhm J, Vasli N, Maurer M,et al. Altered splicing of the BIN1 muscle-specific exon in humans and dogs with highly progressive centronuclear myopathy. PLoS Genet. 2013 Jun;9(6):e1003430.