DR Medhat MRCP

Trinucleotide repeat disorders
- They are genetic conditions caused by an abnormal number of repeats (expansions)
of a repetitive sequence of three nucleotides.
- These expansions are unstable & may enlarge which may lead to an earlier age of
onset in successive generations (= phenomenon known as `Anticipation`).
• Examples for trinucleotide repeat disorders :
1) Fragile X syndrome (CGG).
2) Huntington`s disease(CAG)
3) Myotonic dystrophy (CTG)
4) Friedrich`s ataxia
5) Spinocerebellar muscle atrophy.
6) Bulbospinal neuropathy
7) Dentorubral pallidoluysian atrophy.
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