Overview
Hereditary ataxias are a group of genetic disorders characterised by the progressive degeneration of the cerebellum (and sometimes the spinocerebellar tracts) leading to incoordination of gait and poor coordination of the hands, speech, and eye movements.
Friedreich’s Ataxia
Overview
Friedrich’s ataxia is an autosomal recessive trinucleotide repeat disorder due to a GAA repeat in the X25 gene on chromosome 9 which encodes for frataxin.
Unlike other trinucleotide repeat disorders such as Huntington’s disease, Friedrich’s ataxia does not demonstrate anticipation.
Features
Friedrich’s ataxia typically presents at around 10-15 years of age with:
- Gait ataxia
- Kyphoscoliosis
- Dysarthria
- Loss of reflexes
- Pes cavus
- Hypertrophic obstructive cardiomyopathy – most common cause of death
Ataxia–Telangiectasia
Overview
Ataxia-telangiectasia (AT) is an autosomal recessive disorder due to a defect in the ATM gene which is involved in recognising and repairing damaged DNA. It is characterised by ataxia and telangiectasia.
Features
AT tends to present in early childhood with:
- Cerebellar ataxia
- Telangiectasia
- Pes cavus
- Immunodeficiency:
- Recurrent infections
- IgA deficiency
- Poor vaccine responses
- Increased risk of malignancy:
