Limb-Girdle Muscular Dystrophy, Type 2D / R3

What is Limb-Girdle Muscular Dystrophy?

Limb-Girdle Muscular Dystrophy (LGMD) is a group of rare muscular disorders that generally first present with weakness in the muscles around the hips and shoulders. There are over 30 genetic sub-types (forms) of LGMD. Although muscle weakness is found in every subtype, there are many differences between the diseases including: age of onset, inheritance patterns, and disease severity.    

Limb-girdle muscular dystrophy is separated into two main categories based on the inheritance pattern where:

• 1 designates a dominant disease.
• 2 is a recessive disease. 

The letters at the end of the disease name were assigned in alphabetic order as the genetic basis for each disease was discovered. 

LGMD2D was the fourth recessive limb-girdle muscular dystrophy to be characterized.

What is LGMD2D?

Limb-Girdle Muscular Dystrophy, type 2D / R3, is caused by mutations in the alpha-sarcoglyan gene that lead to a deficiency of functional alpha-sarcoglycan protein. LGMD2D is believed to be the most common of the LGMD sarcoglycanopathies. Sarcoglycanopathies as a whole comprise of about 15% of all LGMD patients. 

LGMD2D causes weakness of muscles in the hip, shoulder, and abdomen. Symptoms often appear before age 10 but, in some cases, do not appear until adulthood. The severity of the disease varies greatly between individuals, even within family members; in some cases, symptoms are mild with no effect on lifespan but, in extreme cases, the disease can be fatal and shorten life expectancy. There are no effects on intelligence or mental function at any age.

Genetic Testing

Because each type of limb-girdle muscular dystrophy is caused by a different gene type, a genetic test is required. It is very important to diagnose patients genetically because patient care can differ dramatically between sub-types. Additionally, patients cannot generally participate in clinical studies or trials without a complete diagnosis.   

To be diagnosed with LGMD2D, a genetic test is required to confirm the presence of mutations in the alpha-sarcoglycan gene. There are several programs in the U.S. that offer free, no-cost genetic testing, including: 

• Invitae
• The Lantern Project
• Rare Genomes Project

 Talk with a doctor or genetic counselor to understand which program is right for you.