Table 1.
Patients with mild mutations in at least one disease gene allele and atypical LD course compared to the patient in the present study with gene‐inactivating mutation and typical course
| References | Sex | Mutation type/gene | Nucleotide (amino acid change) | Age of onset | Age at follow‐up | Clinical status at time of follow‐up |
|---|---|---|---|---|---|---|
| Present paper | F | Nonsense/EPM2A | c.163C>T (p.Gln55Ter) | 13 | 20 | Severe cognitive impairment; severe myoclonus; limited speech; unable to walk or feed |
| 7 | M | Missense/ EPM2B | c.436 G>A (D146N) | 19 | 32 | Mild myoclonus; normal cognition |
| 7 | M | Missense/ EPM2B | c.436 G>A (D146N) | 21 | 29 | Mild myoclonus; normal cognition |
| 7 | M | Missense/ EPM2B | c.436 G>A (D146N) | 17 | 28 | Mild myoclonus; normal cognition |
| 7 | M | Missense/ EPM2B | c.436 G>A (D146N) | 21 | 25 | Mild myoclonus; normal cognition |
| 8 | M | Missense/ EPMzx 2B | c.436 G>A (D146N) | 30 | 48 | Dementia; no disabling myoclonus |
| 9 | F | Missense/ EPM2B | c.436 G>A (D146N) | 19 | 22 | Cognitive impairment; no myoclonus |
| 10 | M | Missense/ EPM2B | c.436 G>A (D146N) | 15 | 29 | Mild cognitive impairment; no interference with daily living activities; mild myoclonus |
| 10 | M | Missense/ EPM2B | c.436 G>A (D146N) | 18 | 28 | Mild cognitive impairment; no interference with daily living activities |
| 10 | M | Missense/ EPM2B | c.436 G>A (D146N) | 13 | 32 | Mild cognitive impairment; no interference with daily living activities; absence seizures |
| 11 | F | Compound heterozygous/ EPM2A | c.721G> T (p.R241X) (nonsense) and c.835G> T (p.G279C) (missense) | 21 | 28 | Mild myoclonus; slow progressing ataxia; mild to moderate cognitive decline. |
| 11 | F | Compound heterozygous/ EPM2A | c.721G> T (p.R241X) (nonsense) and c.835G> T (p.G279C) (missense) | 25 | 30 | Mild cognitive impairment; no ataxia; some myoclonus and GTCS |
| 11 | F | Compound heterozygous/ EPM2A | c.721G> T (p.R241X) (nonsense) and c.835G> T (p.G279C) (missense) | 28 | 33 | No cognitive impairment; no ataxia; myoclonus only |
| 12 | F | Missense/ EPM2A | c.962T>G (p. F321C) | Early 20s | 53 | Slowly progressing bradykinesia; rigidity in limbs; mild cognitive decline |