Trinucleotide repeat disorders

Disorder

Genetic cause

Inheritance pattern

1. Myotonic dystrophy Type 1

CTG repeat
in DMPK gene

Autosomal dominant

2. Friedreich’s ataxia

GAA repeat
in FXN gene

Autosomal recessive

3. Hutington’s disease

CAG repeat
in HTT gene

Autosomal Dominant

4. Fragile X syndrome

CGG repeat
in FMR1 gene

X-Linked dominant

5. Spinocerebellar Ataxia

Various repeats
in different genes
(often CAG)

Autosomal dominant