Table 1  Genetic and Clinical Findings in Individuals with TRMT5 Variants
ID   Sex   TRMT5 Variants a   OXPHOS Activities in Skeletal Muscle   Clinical Features
Respiratory-Chain Complex   Enzyme Activity   Absolute Values   Reference Range (Mean ± SD [range])   Histo-chemical COX Defect   Age at Onset   Clinical Course   Other Features
73901b  female  c.[312_315del;872G>A], p.[Ile105Serfs∗4;Arg291His]  I  59%  2.9  4.9 ± 0.9 (3.1–6.7)  >95% COX-deficient fibers  childhood  died at 55 years of age  life-long exercise intolerance, dyspnea, lactic acidosis, pancreatic disorder, spasticity/peripheral neuropathy, muscular weakness, renal tubulopathy, cirrhosis
II  138%  2.9  11.2 ± 2.7 (5.8 −16.6)
II+III  47%  5.3  2.1 ± 0.6 (0.9–3.4)
IV  36%  1.4  3.9 ± 1.3 (1.3–6.6)
65205c  male  c.[312_315del;1156A>G], p.[Ile105Serfs∗4;Met386Val]  I  32%  88  272 ± 115 (84–559)  none  birth  alive, 7 years old  premature delivery, failure to thrive, growth retardation, intestinal pseudo-obstruction, hypertrophic non-obstructive cardiomyopathy, muscular hypotonia, demyelinating neuropathy, global developmental delay, lactic acidosis
II  ND  ND  ND
II+III  136%  154  110 ± 70 (37–285)
IV  27%  315  1150 ± 400 (520–2080)
Abbreviation is as follows: ND, no data.
a  cDNA (GenBank: NM_020810.3), protein (GenBank: NP_065861.3).
b  For subject 73901, enzyme activities are expressed as percentage of control enzyme activity. Absolute values of residual enzyme activities are expressed as U/min/g wet weight, and the reference range (mean ± SD [range]) is shown for 46 control subjects.
c  For subject 65205, percentages of residual enzyme activities are normalized to citrate synthase activity. Absolute values are expressed as mU/U citrate synthase activity, and the reference range is shown for 52 (complex I) and 27 (complex II+III and IV) control subjects.