A methylation PCR method determines FMR1 activation ratios and differentiates premutation allele mosaicism in carrier siblings

Table 1 Sibling pairs and neurological phenotypes associated with repeat length and activation ratio

Pair	Neurological phenotype	Onset of neurological signs	CGG repeats	Activation ratio (SB)	Activation ratio (mPCR)	FXTAS motor rating scale	Neuro-imaging	FXTAS
1	Kinetic tremor, gait ataxia, parkinsonism	70	20/75, 79	20%	34%	20	Hyperintensities in white matter, midline pons	Definite FXTAS
1	Mild gait ataxia	60	23/118, 139, >200	50%	39%	7	Hyperintensities (mild) in white matter	Possible FXTAS
2	Kinetic tremor, gait ataxia, parkinsonism	75	25/68, 80, 86	20%	29%	44	Hyperintensities in deep white matter, brainstem, cerebellum	Definite FXTAS
2	Kinetic tremor, gait ataxia, parkinsonism	90	25/90, 99	90%	79%	74	N/A	Probable FXTAS
3	Numbness, dystonia of feet	51	27/66, 68	20%	16%	1	N/A	No
3	Numbness of feet	61	27/58, 69, 71	50%	45%	4	N/A	No
4	Mild kinetic tremor, falls	72	30/72, 74	10%	27%	15	Hyperintensities (mild) in white matter	Possible FXTAS
4	Mild kinetic tremor	79	30/79, 82	40%	35%	7	N/A	No
5	Mild kinetic tremor, mild gait ataxia	60	20/91, 95	80%	81%	12	N/A	Probable FXTAS
5	Kinetic tremor, falls, dystonia	54	30/102, 110	20%	30%	7	N/A	No
6	Kinetic tremor, gait ataxia, parkinsonism	78	29/77, 80	80%	81%	14	N/A	Probable FXTAS
6	Kinetic tremor, gait ataxia, parkinsonism	83	32/76, 78	40%	29%	13	N/A	Probable FXTAS
7	None	N/A	30, 94, 100	90%	82%	2	N/A	No
7	None	N/A	30, 94, 100	10%	22%	4	N/A	No

Summary of phenotype, age of onset of neurological signs and results linking genotype, activation ratio by Southern blot (SB) and mPCR analysis and rating information for fragile X tremor and ataxia syndrome (FXTAS) by sibling pair