ATM and ataxia telangiectasia: In addition to the enhanced carcinogenesis, unrepaired breakage at extracellular signal-dependent enhancers can cause symptoms of ataxia-telangiectasia (A-T), the autosomal recessive disease caused by ATM mutations.134 For example, the progressive cerebellar degeneration of people with A-T disorder may result from altered transcriptional responses to neurotransmitters, resulting in the gradual loss of neurons.