| Current subtype / legacy name | Causal gene / protein | Inheritance | Hallmark severity / onset | Cardiac / respiratory notes | Key evidence / statistics |
|---|---|---|---|---|---|
| LGMDR3 / LGMD2D | **SGCA** / α-sarcoglycan | Autosomal recessive | In the 100-patient sarcoglycanopathy cohort, α-SG cases had later mean onset than γ-SG: **8.0 years**; phenotype is variable from severe childhood-onset to milder late-onset forms. Earlier onset predicts earlier loss of ambulation. (pqac-00000018, pqac-00000003) | Dilated cardiomyopathy can occur across all sarcoglycanopathy subtypes; heart and respiratory surveillance are recommended. (pqac-00000018, pqac-00000017) | α-SG was one of the major subtypes in the 100-patient cohort (**41/100**). In the broader Dutch AR-LGMD/Miyoshi cohort, sarcoglycanopathies represented **67/244 (27%)** of cases. (pqac-00000018, pqac-00000003) |
| LGMDR4 / LGMD2E | **SGCB** / β-sarcoglycan | Autosomal recessive | Often severe, but heterogeneous. In one 32-patient series, phenotypes were **15 severe, 12 mild, 5 unknown**; another multicenter cohort reported mean onset around **24.4 years** for β-SG cases represented there, highlighting variability and probable ascertainment effects. (pqac-00000002, pqac-00000018) | Cardiac involvement is prominent: **63%** had cardiac involvement, **19%** dilated cardiomyopathy, **28%** rhythm abnormalities; **19%** required respiratory support. Constant surveillance is emphasized, especially for LGMDR4. (pqac-00000002, pqac-00000017) | Estimated prevalence reported as **0.86 × 10⁻⁶**. First-in-human SGCB gene therapy trial enrolled **6** patients aged 4–15 years; Day-60 SGCB expression reached **36.2%** and **62.1%** of normal in low/high dose cohorts, respectively. (pqac-00000002, pqac-00000019, pqac-00000025) |
| LGMDR5 / LGMD2C | **SGCG** / γ-sarcoglycan | Autosomal recessive | Typically earlier and more severe. In the 100-patient cohort, γ-SG cases had mean onset **5.5 years** and more frequent severe progression with early loss of ambulation. (pqac-00000018, pqac-00000003) | Dilated cardiomyopathy occurred in all subtypes and was reported **especially in γ-SG patients**; respiratory problems needing ventilation are common in sarcoglycanopathy overall. (pqac-00000018, pqac-00000017) | In the French multicenter cohort, γ-SG was the largest subgroup (**54/100**); **>90%** carried the homozygous **c.525delT** frameshift variant, indicating a strong founder effect in some populations. (pqac-00000018) |
| LGMDR6 / LGMD2F | **SGCD** / δ-sarcoglycan | Autosomal recessive | Ultra-rare and generally severe/rapidly progressive. In the largest international cohort, **60%** were wheelchair-bound from early teens with median loss of ambulation at **12.0 years**; distal weakness appeared early in **56.5%**. Absent sarcoglycan expression predicted earlier onset and ambulation loss. (pqac-00000001, pqac-00000004) | Cardiac involvement in **21.7%** (5/23); **17.4%** (4/23) required non-invasive ventilation. Surveillance is recommended, especially because cardiomyopathy can occur across sarcoglycanopathies. (pqac-00000001, pqac-00000017) | Largest cohort identified **23** analyzed patients from **18 families** across **9 countries**; **87%** had consanguineous parents, supporting enrichment in consanguineous settings. Geographic concentration has been noted in Brazil. (pqac-00000004, pqac-00000018) |


*Table: This table summarizes the four canonical sarcoglycanopathy subtypes for knowledge-base use, linking nomenclature, gene/protein, inheritance, and major clinical distinctions. It highlights the strongest gathered quantitative evidence on onset, severity, and cardio-respiratory burden.*