The NM_000232.5: c.377_384dup p.(Gly129delinsGlnTer) variant in SGCB, which is also known as p.(Gly129GlnfsTer2), is a presumed in tandem duplication of nucleotides 377-384, which is predicted to cause a frameshift and introduce a premature stop codon in biologically relevant exon 3/6, leading to nonsense mediated decay in a gene in which loss of function is an established disease mechanism (PVS1). This variant has been detected in at least 10 individuals with limb girdle muscular dystrophy, including in a homozygous state in four (1.0 pt) and confirmed in trans with a likely pathogenic or pathogenic variant in two (c.699_702del, 1.0 pt; c.85A>T p.(Arg29Ter), 1.0 pt) (PMID: 25862795, 36077211, 10662809; PM3_Strong). This variant has been reported to segregate with autosomal recessive LGMD in two affected family members from two Italian families (PMID: 25862795; PP1_Moderate). At least one patient with this variant and a second SGCB variant showed a progressive LGMD phenotype and significantly reduced expression of beta-sarcoglycan in skeletal muscle, which is highly specific for SGCB-related LGMD (PP4_Moderate (capped with PP1_Moderate); PMID: 36077211). The highest minor allele frequency of this variant is 0.000008791 in the European (non-Finnish) population in gnomAD v2.1.1 (1/113750 exome chromosomes), which is lower than the LGMD VCEP threshold (<0.00009) for PM2_Supporting, meeting this criterion (PM2_Supporting). In summary, this variant meets the criteria to be classified as Pathogenic for autosomal recessive limb girdle muscular dystrophy based on the ACMG/AMP criteria applied, as specified by the ClinGen LGMD VCEP (LGMD VCEP specifications version 1.0.0; 01/08/2025): PVS1, PM3_Strong, PP1_Moderate, PP4_Moderate, PM2_Supporting.