Table 2 Clinical symptoms and mutation load in the four tissues.

Clinical symptoms	n		Mutation load (%)
		Age	Blood	Buccal	UEC	Muscle
		(years)		mucosa
MELAS, epilepsy, HI, ataxia	2	18 to 25	30 to 44	71	72	87 to 92
MIDD, encephalopathy, EIT	5	21 to 42	30 to 57	44 to 65	48 to 96	37 to 90
MIDD	8	37 to 74	10 to 39	29 to 67	18 to 90	69
MIDD, EIT	10	35 to 65	9 to 38	28 to 53	18 to 91	62 to 84
IGT, HI, EIT	4	60 to 74	4 to 57	18 to 22	41 to 83	50 to 90
IGT	5	37 to 61	4 to 19	11 to 32	7 to 34	18 to 56
HI	2	10 to 48	17 to 70	70	94	71 to 82
CU	23	7 to 66	0 to 61	0 to 79	0 to 92	0 to 83
Other*	6	13 to 62	0 to 55	0 to 58	0 to 70	0 to 76

*Gastropathy, nephropathy, ataxia, cardiomyopathy, tinnitus.

CU, clinically unaffected; EIT, exercise intolerance; HI, hearing impairment; IGT, impaired glucose tolerance; MIDD, maternally inherited deafness and diabetes mellitus; n, number of subjects.