Limb-Girdle Muscular Dystrophy Type 2D (LGMDR3)
Summary
LGMD2D (now called LGMDR3 under revised nomenclature) is a progressive muscular dystrophy caused by deficiency of alpha-sarcoglycan, a component of the dystrophin-associated glycoprotein complex that stabilises muscle cell membranes during contraction. Symptoms typically begin in childhood with proximal muscle weakness — difficulty climbing stairs, rising from the floor, and running. Progression is variable: some individuals lose ambulation in adolescence, while milder cases maintain walking into adulthood. Cardiac involvement can occur. Respiratory muscles may be affected in advanced disease.
Practical takeaway
Given the relatively low general carrier frequency, partner testing is most relevant if there is family history of muscular dystrophy. Realised does not calculate reproductive risk or advise on reproductive decisions.
Evidence detail
What Carrier Status Means For You
You are not affected. One working copy of SGCA is sufficient. Standard 25/50/25 recessive inheritance applies.
Population Context
LGMD2D occurs across all populations. R77C is the most common European variant. Sarcoglycanopathies collectively account for ~10-25% of all LGMD depending on the population studied.
Limitations
23andMe tests 1 SGCA variant. Coverage is minimal. Comprehensive muscular dystrophy gene panels cover all sarcoglycan genes and many other LGMD genes.