Signs of the disorder usually become noticeable between 1-4 years. Speech problems occur but, after a period of deterioration, a stable state is reached and speech is always understandable. There is often a gradual loss of power as well as other co-ordination problems over the decades. The diagnostic finding is an increased sensitivity to high doses of ionising radiation. However, normal x-rays are not injurious to affected individuals as radiation dosages are very low.
Inheritance patterns The mode of inheritance is autosomal recessive.
Two genes have been found which can cause Ataxia Telangiectasia. The major gene is called ATM and is located on chromosome 11q23. Many different mutations in the ATM gene have been found. It is difficult to search for all gene faults and currently this is not available as an NHS laboratory service. A second gene, hMre11,has also been identified.