Table 1.
Genetic muscle diseases that can present at a very old age.
| Muscle disease | Gene, locus | Mutation type | Age of onset |
|---|---|---|---|
| Tibial muscular dystrophy | TTN (titin), 2q31 | Dominant, insertion–deletion, missense, truncating | 35–40 distal weakness, rarely after 60 years; 60–80 proximal weakness |
| Welander distal myopathy | TIA1, 2p13 | Dominant, missense | 40–60 infrequently after 60 years |
| LGMD1A | TTID (myotilin), 5q31 | Dominant, missense | 50–60 up to 77 years |
| LGMD1D | DNAJB6, 7q36.3 | Dominant, missense | 20–50 up to 70 years |
| IBMPFD | VCP, 9p13.3 | Dominant, missense | Mean age 42 can be over 60 |
| Oculopharyngeal muscular dystrophy | PAPBN1, 14q11.2 | Dominant/recessive, repeat expansion | 50–60 or later in heterozygotes |
| DM1, late-onset oligosymptomatic | DMPK, 19q13.3 | Dominant, repeat expansion | Over 50 |
| DM2 | CNBP (ZNF9), 3q21 | Dominant, repeat expansion | 20–60, proximal weakness manifests later in typical cases |
| Acid maltase deficiency, adult-onset | GAA (acid α-glucosidase), 17q25.2-q25.3 | Recessive, missense, nonsense, frameshift | Early adulthood up to 72 years |
| Mitochondrial myopathy | mtDNA defects | Dominant/recessive, maternal, sporadic, point mutations, deletions | Any age up to 70 years |
LGMD, limb-girdle muscular dystrophies; IBMPFD, inclusion body myopathy with Paget disease and frontotemporal dementia; DM1, myotonic dystrophy type 1; DM2, myotonic dystrophy type 2; mtDNA, mitochondrial DNA.