Muscular Dystrophies are a group of diseases characterized by skeletal muscle weakness and progressive degeneration. In some dystrophies, the heart and diaphragm are affected.
Limb-Girdle Muscular Dystrophies (LGMD) are one of the many types of muscular dystrophies. The muscles primarily affected in LGMDs are the voluntary muscles around the girdle areas, the hips and shoulders. The girdles are the sets of bones which connects to the limbs. The set of bones connecting to the arms is called the pectoral girdle and the set of bones connecting to the legs is called the pelvic girdle.
There are at least 30 different forms of LGMD. The LGMD1s are inherited in an autosomal dominant manner; the LGMD2s are inherited in an autosomal recessive manner.
The onset, progression, and distribution of the weakness and muscle degeneration vary considerably among genetic subtypes. It varies also among individuals of a same subtype.
It is challenging to determine the prevalence of LGMDs because of low awareness and knowledge of people and doctors, and because of the lack of definitive diagnosis. As genetic sequencing becomes cheaper and as our knowledge of the genetic basis of muscular diseases increases, definitive diagnosis will become more prevalent. The number of people with LGMDs worldwide could be as high as 500,000.
Today, there is no cure for any muscular dystrophies. In some severe cases, medications exist to slow the course of disease or improve the quality of life.