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Table 1 Clinical data for YARS2 patients

From: Phenotypic variability and identification of novel YARS2 mutations in YARS2 mitochondrial myopathy, lactic acidosis and sideroblastic anaemia

Patient P1 P2a P3 P4 P5 P6
YARS2 variant [c.156C > G]; [c.156C > G] [p.Phe52Leu]; [p.Phe52Leu] [c.156C > G]; [c.156C > G] [p.Phe52Leu]; [p.Phe52Leu] [c.156C > G]; [c.156C > G] [p.Phe52Leu]; [p.Phe52Leu] [c.156C > G]; [c.156C > G] [p.Phe52Leu]; [p.Phe52Leu] [c.156C > G]; [c.156C > G] [p.Phe52Leu]; [p.Phe52Leu] [c.572G > A]; [c.1078C > T] [p.Gly191Asp]; [p.Arg360X]
mtDNA haplogroup K1a4f1 K1 K1a4f T1a8 H ND
RC Enzyme Activityb Muscle Fibroblast Muscle Fibroblast Muscle Fibroblast Muscle Liver Muscle Fibroblast Muscle Lymphocyte
Complex I/CS 8 62 3 ND 25 80 2 49 ND ND ND 85
Complex II/CS 150 116 139 ND 110 39 132 191 ND ND ND 94
Complex III/CS ND 107 3 ND ND 56 4 105 ND ND ND 67
Complex IV/CS 12 89 2 ND 7 52 3 85 ND ND ND 70
CS c 236 67 319 ND 94 94 376 254 ND ND ND 319
Sideroblastic anaemia Severe Moderate Mild Severe Mild Mild
  Transfusion dependent from birth Transfusion dependent from birth to 17 y From 7 y Transfusion dependent from birth From 23 y Transfusion dependent during first year
Not transfused for personal reasons   Not transfusion dependent
Hb 70–110 g/L Hb 42 g/L Hb 104 g/L
Lactic acidosis Severe Moderate Mild Severe Mild Mild
3–13.7 mmol/L 2.5-8.4 mmol/L 4.1 mmol/L 27 mmol/L 3.24-5.10 mmol/L 2–3 mmol/L
Myopathy Severe Moderate Mild ND Mild Mild
Other features Cardiomyopathy in infancy Currently 20 y with improvement in clinical features Currently 27 y Cardiomyopathy Currently 28 y Currently 6 y
Deceased at 18 y Deceased at 3 mo
  1. aSibling of P1.
  2. bValues expressed as % residual activity.
  3. cCitrate synthase activity was expressed relative to protein.
  4. CS = citrate synthase.
  5. ND = not determined.