Triplet repeats and fragile sites

Inherited Diseases Involving Repeated Trinucleotides That Are Present in an Excessive Number of Copies  

Fragile X syndrome CGG 5-54 unaffected 60-230 carriers 230-4000 affected Mental retardation 

Huntington s disease CAG 11-30 unaffected 36-121 affected Chorea, progressive dementia, death 

Spinocerebellar ataxia Type 1 CAG 19-36 unaffected 40-81 affected Ataxia, dysarthria, rigidity, abnormal eye movements 

Fredreich s ataxia GAA 7—22 unaffected 200-900 affected Ataxia, dysarthria, hypertropic cardiomyopathy, diabetes 

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