LGMD

Limb-girdle muscular dystrophy (LGMD) is a term that applies to over 20 different genetic muscle disorders. Each of these disorders is characterised by weakness of the muscles around the shoulders and hips (the “limb-girdles” of the body). The symptoms and severity of LGMD can vary greatly from one person to another, but many people with LGMD will have difficulty walking, climbing stairs, and lifting items above their head. LGMD is the fourth most common genetic cause of muscle weakness.

There are many different genes that can cause LGMD. These genes are passed from parent to child in two patterns: in an autosomal recessive pattern, or an autosomal dominant pattern. There are some cases where the disease-causing gene is not inherited, but rather it spontaneously occurs in the child during pregnancy (it is de novo).

Autosomal recessive LGMD

Every gene exists as two copies (alleles), and we inherit these copies from our parents. One copy comes from our mum, and one copy comes from our dad. Genetic diseases can be passed down if one or both copies of a gene are non-functional (mutated).

In autosomal recessive LGMD, a person must have two mutated gene copies for them to have LGMD, and it is equally likely to occur in males and females. If a person has one mutated gene copy and one healthy gene copy, then they are called a “carrier” of LGMD. Carriers of LGMD are unlikely to ever develop LGMD themselves.

LGMD types R1 to R24 are categorised as autosomal recessive LGMD.

Autosomal dominant LGMD

Every gene exists as two copies (alleles), and we inherit these copies from our parents. One copy comes from our mum, and one copy comes from our dad. Genetic diseases can be passed down if one or both copies of a gene are non-functional (mutated).

In autosomal dominant LGMD, a person only needs one mutated copy of their gene to have LGMD, and it is equally likely to occur in males and females. Although the other copy of the gene is healthy, in these cases, having only one working copy of a gene is not enough for the body to produce what it needs.

LGMD types D1 to D5 are categorised as autosomal dominant LGMD.