Mild clinical features of isolated methylmalonic acidemia associated with a novel variant in the MMAA gene in two Chinese siblings

Table 1 Biochemical, clinical, and genetic characteristics of the siblings

Patient no.	Gender	Current age	Age at test	MS/MS analysis			Methylmalonic acid (mmol/mol creatinine)^d	Methycitrate (mmol/mol creatinine)^e	Homocysteine (μmol/L)^f	DQ	Cerebral MRI	Genotype
Patient no.	Gender	Current age	Age at test	C3 (μmol/L)^a	C3/C2^b	C3/C0^c	Methylmalonic acid (mmol/mol creatinine)^d	Methycitrate (mmol/mol creatinine)^e	Homocysteine (μmol/L)^f	DQ	Cerebral MRI	Genotype
II:1	Male	10 y, 8 m	9 y, 9 m	4.96	0.53	0.26	32.51	0.24		ND	Normal	Homozygous for c.365T>C variant
			9 y, 11 m	1.22	0.31	0.12	13.29	0.76	6.07	ND	Normal	Homozygous for c.365T>C variant
II:2	Female	1 y, 2 m	4 d (NBS)	7.05	0.71	0.85						Homozygous for c.365T>C variant
			12 d	8.14	1.3	0.81	56.46	5.49
			45 d	9.93	1.54	1.01
			50 d^g	19.76	1.08	0.57
			2 m	6.3	0.28	0.11	8.88	3.95	6.5		Normal
			3 m	3.95	0.24	0.08	39.39	1.97
			5 m	4.93	0.21	0.1	15.24	1.35
			8 m	8.49	0.29	0.21	48.97	1.88		92.8
			1y, 1 m	7.76	0.38	0.19	42.71	1.25		84.1

C3 Propionylcarnitine, C2 Acetylcarnitine, C0 Free carnitine, NBS Newborn screening, y Year, m Month, d Day, DQ Development quotient, ND Not determined, MRI Magnetic resonance imaging
^anormal range: 0.50–4.50 μmol/L
^bnormal range: 0.01–0.20
^cnormal range: 0.02–0.20
^dnormal range: 0.3–3.6 mmol/mol creatinine
^enormal range: 0.2–1.1 mmol/mol creatinine
^fnormal range: 0-15 μmol/L
^gTreatment was commenced on day 50

ISSN: 1471-2350