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

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

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
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
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
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
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
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
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
None N/A 30, 94, 100 10% 22% 4 N/A No
  1. 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