From the Guidelines
The incidence of limb girdle muscular dystrophy is estimated to be approximately 1 in 14,500 to 1 in 123,000 people, according to the most recent and highest quality study available 1. This estimate may vary depending on the specific subtype and geographic region, as some forms are more common in certain populations due to founder effects or consanguinity.
- The condition encompasses over 50 genetic subtypes, each with its own specific incidence rate, contributing to the wide range in overall prevalence estimates.
- The actual incidence may be underestimated due to diagnostic challenges, including clinical overlap with other neuromuscular disorders and limited genetic testing in some regions.
- LGMD affects both males and females equally in most subtypes, as many forms follow autosomal inheritance patterns, though age of onset and disease progression can vary considerably even within the same subtype.
- The broad clinical heterogeneity among the various LGMDs emphasizes the importance of accurate diagnosis to ensure appropriate cardiac evaluation and follow-up, as cardiac involvement is very common in certain subtypes, such as lamin A/C and sarcoglycan disease 1.
From the Research
Incidence of Limb Girdle Muscular Dystrophy
- The incidence of limb girdle muscular dystrophy (LGMD) is not explicitly stated in the provided studies, but it is mentioned that LGMDs are a group of rare, genetic progressive muscle disorders 2, 3.
- The studies suggest that LGMDs are genetically heterogeneous disorders, with over 29 individual genes causing the disease 2.
- The prevalence of LGMD can be estimated using public sequencing databases, and a Bayesian method has been developed to estimate the disease prevalence for nine recessive LGMD subtypes 4.
- The estimated disease prevalence calculated by this method was largely comparable with published estimates from epidemiological studies, but it highlighted instances of possible underdiagnosis for certain subtypes of LGMD 4.
- The lack of epidemiology data and the low incidence of LGMDs make it difficult to get a robust and generalizable prevalence estimation for each subtype 4.
Characteristics of Limb Girdle Muscular Dystrophy
- LGMDs are characterized by a common feature of limb-girdle pattern of weakness, caused by mutations in muscle structural or repair proteins 2.
- The disease can have autosomal recessive or autosomal dominant inheritance, with different ages of onset and disease progression 2, 3.
- Certain mutations are associated with cardiac or respiratory involvement, and the disease can cause progressive disability and potential loss of ability to walk or maintain a job due to progressive muscle wasting 2, 3.
Diagnosis and Management of Limb Girdle Muscular Dystrophy
- The diagnosis of LGMD can be made using a combination of clinical evaluation, muscle imaging, and laboratory exams, including genetic testing and muscle biopsy 3, 5.
- The management of LGMD typically involves a multidisciplinary clinic model, with a focus on improving the quality of life and managing complications such as cardiac and respiratory involvement 2, 3.
- New approaches, such as gene replacement, gene transfer, and anti-myostatin therapy, are being explored as potential treatments for LGMD 6.