Limb-Girdle Muscular Dystrophy and Distal Myopathy
STR: TBC1D7_OPDM_CGG
Preprint PMID 41959811 reports 3 families with a heterozygous 5'UTR CCG expansion in TBC1D7 and oculopharyngodistal myopathy. Affected individuals had 83, 87, 113, 137 and 148 repeats (n=5). All 3 families share a core 16 kb haplotype, consistent with a common ancestral origin. An unaffected transmitting father carries the largest allele, 184 repeats, hypermethylated. Gain of function is the proposed mechanism of disease. Patient-derived fibroblasts show increased TBC1D7 expression, and muscle biopsy shows p62-positive intranuclear inclusions, supporting a dominant toxic gain-of-function mechanism analogous to other CCG-expansion disorders. No normal range is defined. 79/70,752 GE control alleles had >50 repeats.
The reference and 94.3% of 1,718 control alleles carry an interrupted CCGCTG structure, while patient alleles are long pure CCG.
Sources: LiteratureCreated: 2 Sep 2026, 9:35 p.m.
Mode of inheritance
MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Phenotypes
Oculopharyngodistal myopathy, TBC1D7-related MONDO:0025193
Publications
Str: tbc1d7_opdm_cgg has been classified as Amber List (Moderate Evidence).
Str: tbc1d7_opdm_cgg has been classified as Amber List (Moderate Evidence).
STR: TBC1D7_OPDM_CGG was added STR: TBC1D7_OPDM_CGG was added to Limb-Girdle Muscular Dystrophy and Distal Myopathy. Sources: Expert Review Green,Literature Mode of inheritance for STR: TBC1D7_OPDM_CGG was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for STR: TBC1D7_OPDM_CGG were set to 41959811 Phenotypes for STR: TBC1D7_OPDM_CGG were set to Oculopharyngodistal myopathy, TBC1D7-related MONDO:0025193