Table 2 Reason for disease causing mutation was not identified by standard testing. The reason “Genetic heterogeneity” was selected when the presenting phenotype was consistent with that reported due to mutations in this gene but had not been previously tested as several genes are associated with this phenotype
Reason | No. of occurrences | Genetic diagnoses |
|---|---|---|
Whole gene sequencing not previously available | 6 | TTN |
Genetic heterogeneity | 5 | COL6A1, COL6A3, VCP, DNM2, SLC2A1 |
Recent gene discovery | 3 | STIM1, GMPPB |
Specific muscle biopsy immunoanalysis not originally performed | 3 | LAMA2 (2 occurrences), CAV3 |
Polymorphism reclassified as pathogenic | 3 | SGCG, CAPN3 (2 occurrences) |
Mutation missed by Sanger sequencing | 2 | CAPN3, COL6A1 mosaic |
Disease rarity | 2 | PIEZO2, MTM1 manifesting carrier |
Atypical phenotype | 2 | MEGF10, DYSF |
Inheritance pattern misleading | 1 | MYH7 |
Mutation missed by previous gene screening technique (DHPLC) | 1 | LMNA |