Definition of Limb-girdle muscular dystrophies:

Limb-girdle muscular dystrophies include at least 10 different inherited disorders, which initially affect the muscles around the shoulder girdle and the hips. These diseases are progressive and may involve other muscles over a period of time.

Causes, incidence, and risk factors:

This is a large group of genetic diseases featuring muscle weakness and wasting (muscular dystrophy). Most are inherited in an autosomal recessive manner (both parents must pass on the defective gene for a child to have the disease), but some are autosomal dominant (only one parent needs to pass on the bad gene to affect the child). For some of these conditions, the defective gene has been discovered, but for others, the gene is not yet known.

Typically, the first sign is pelvic muscle weakness (difficulty standing from a sitting position without using arms, difficulty climbing stairs), which starts in childhood to young adulthood. Later there is the shoulder weakness. The disease will cause significant loss of mobility or wheelchair dependence over the next 20-30 years.

An important risk factor is having a family member with muscular dystrophy.