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

Table 1 Clinical data for YARS2 patients

Patient	P1		P2^a		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 Activity^b	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
Lactic acidosis	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
Other features	Deceased at 18 y		Currently 20 y with improvement in clinical features		Currently 27 y		Deceased at 3 mo		Currently 28 y		Currently 6 y

ISSN: 1750-1172