Table 1.
Patient summary
| Case No | cDNA (NM_018127.6) | Protein (NP_060597) | Identification | Sex | Age‐at‐onset (months) | Course | Cardiomyopathy | MRC deficency | Additional clinical features | Previously reported |
|---|---|---|---|---|---|---|---|---|---|---|
| #57415 | c.631 C>T; c.1559 C>T | p.Arg211∗; p.Thr520Ile | WES | Male | 3 | Unknown | HCM | CI | Psychomotor retardation, mild hypotonia, lactic acidosis, sensorineural hearing impairment, hyperintensities in basal ganglia at age 3 m | Haack et al. (2013) |
| #61982 | c.460 T>C; c.460 T>C | p.Phe154Leu; p.Phe154Leu | WES | Female | 2 | Death at 11 months | HCM | CI | Intrauterine growth retardation, lactic acidosis, cardiac failure; normal muscle biopsy findings | Haack et al. (2013) |
| #65937 | c.1267 C>T; c.1267 C>T | p.Leu423Phe; p.Leu423Phe | CGS | Female | 5 | Death at 4 years and 9 months | HCM | CI | Psychomotor retardation, muscular hypotonia, cardiac failure | Haack et al. (2013) |
| P1 | c.1478 C>T; c.202 C>T | p.Pro493Leu; p.Arg68Trp | WES | Female | Birth | Death at 3 weeks | HCM | CI + CIV | Lactic acidosis, muscle weakness, ragged‐red fibers and COX‐deficient/SDH‐ hyperreactive fibers | Taylor et al. (2014) |
| P2 | c.2009del; c.1423 + 1 G>A | p.Cys670Serfs*14; CSM | GP | Male | Birth | Alive at 8 years | No | ND | Lactic acidosis, developmental delay, ataxia, microcephaly, constipation, cerebellar vermis hypoplasia and prominent posterior fossa on brain MRI | This report |
| P3 | c.297–2_297delinsTG; c.2342 G>A | CSM; p.Arg781His | GP | Female | 18 | Alive at 5 years | HCM | CI | Elevated blood lactate level (normal serum levels), developmental delay, IUGR | This report |
| P4 | c.2186 A>G; c.2342 G>A | p.Tyr729Cys; p.Arg781His | WES | Female | 2 | Death at 12 weeks | HCM | CI | Lactic acidosis, cardiovascular collapse | This report |
| P5 | c.460 T>C; c.460 T>C | p.Phe154Leu; p.Phe154Leu | WES | Male | neonatal | Death at 4 months | HCM | ND | Lactic acidosis, fatal infantile cardiomyopathy | This report |
| P6 | c.798–1 G>T; c.1690C>A | CSM; p.Arg564Ser | GP | Female | 4 | Death at 5 months | DCM | CI | Lactic acidosis, developmental delay, fatal infantile cardiomyopathy, EF 30% | This report |
| P7 | c.1979A>T; c.2039 C>T | p.Lys660Ile; p.Ala680Val | WES | Female | 12 | Alive at 24 years | HCM | CI + CIV | Elevated blood lactate level, Patient transplanted at age of 3.8 years | Parikh et al. (2016) |
| P8 | c.245 + 2 T>A; c.1264 C>G | CSM; p.Leu422Val | WES | Female | 2 | Death at 3 months | DCM | CI | Lactic acidosis, fatal infantile cardiomyopathy, EF 20–30% | This report |
| P9 | c.1163 A>G; c.1163 A>G | p.Gln388Arg; p.Gln388Arg | GP | Male | 6 | Alive at 19 years | HCM | CI | Lactic acidosis, psychomotor retardation, fatigability, peripheral neuropathy | This report |
| P10 | c.457delA; c.2342 G>A | p.Ile153Tyrfs*6; p.Arg781His | WES | Male | 8 | Alive at 6 years | HCM | CI | Developmental delay, hypotonia, GI dysmotility, s/p cardiac transplant at age of 10 months | Santorelli et al. (2002) |
| P11 | c.460 T>C; c.460 T>C | p.Phe154Leu; p.Phe154Leu | WES | Female | Birth | Death at 2.5 months | HCM | CI | Lactic acidosis, later mild muscular hypotonia, lipid storage myopathy on skeletal muscle biopsy | This report |
| P12 | c.297–2_297–1delinsT; c. 2245 C>T | CSM; p.His749Tyr | WES | Female | 4 | Death at 13 months | HCM | CI + CIV | Lactic acidosis, global developmental delay, hypotonia, s/p cardiac transplant at the age of 10 months | This report |
| P13 | c.460 T>C; c.460 T>C | p.Phe154Leu; p.Phe154Leu | WES | Female | 5 | Death at 5 months | HCM | ND | Lactic acidosis, failure to thrive | This report |
Abbreviations: CGS: candidate gene sequencing; CSM: consensus splice mutation; CI: Complex I; CIV: Complex IV; DCM: dilated cardiomyopathy; GP: gene panel; HCM: hypertrophic cardiomyopathy; MRC: mitochondrial respiratory chain; ND: not determined; WES: whole exome sequencing
Note. Cases reported by Haack et al. (2013) are indicated in light gray.