Diagnosis:
Genetic testing: expansion of CGG repeat on FMR1 gene on chr. X.
55-200 repeats = premutation range, associated with tremor/ataxia syndrome and premature ovarian failure
>200 repeats = Fragile X syndrome
Findings on investigations:
MRI: T2 white matter hyperintensities in the middle cerebellar peduncles or brain stem. Cereberal white matter hyperintensities and atrophy may occur.
Pathology:
In white matter enlarged astrocytes with inclusions. Inclusion bodies in neurons and astrocytes occur in the CNS and in autonomic neurons.