Genotype-phenotype correlations in alpha-sarcoglycanopathy: a systematic review.

Area of Science:

• Genetics
• Molecular Biology
• Neurology

Background:

• Limb-girdle muscular dystrophy 2D (LGMD2D) is an autosomal recessive disorder caused by mutations in the alpha-sarcoglycan gene.
• Previous research has not comprehensively cataloged alpha-sarcoglycan mutations and their corresponding phenotypes.
• This study aims to correlate mutation locations and types with clinical manifestations in LGMD2D.

Approach:

• A systematic literature review was conducted to gather all reported mutations in the alpha-sarcoglycan gene.
• Genotype-phenotype data from 134 unique genotypes were analyzed.
• Statistical analysis was used to identify mutation hotspots and significant variations in mutation densities.

Key Points:

• Missense mutations constitute 64% of all identified alpha-sarcoglycan mutations.
• Mutation hotspots were identified in exon three and the extracellular domain.
• All compound heterozygous LGMD2D patients with cardiac involvement had at least one mutation in exon three.
• Nonsense mutations and combinations involving exons four and five result in severe phenotypes.
• The high prevalence of the c.229C>T mutation was confirmed.

Conclusions:

• Significant variation in disease severity exists even among patients with identical mutations, complicating genotype-phenotype correlations in LGMD2D.
• The association of exon three mutations with cardiomyopathy in compound heterozygous patients is a novel finding.
• Identifying mutation hotspots and specific mutation types (e.g., involving exons four and five) can inform diagnostic and therapeutic strategies for personalized medicine.