Louis Bar syndrome, commonly referred to as ataxia-telangiectasia (AT), is identified by its symptoms of ataxia, telangiectasia, elevated alpha-fetoprotein, microcephaly, pulmonary failure, radiosensitivity, immunodeficiency, dysmorphic features, and learning difficulties with a prevalence of 0.001–0.0025% in live births (Boder and Sedgwick, 1970; Swift et al., 1986; Richard and Susan, 1999). The gene discussed is AFP; the disease is ataxia telangiectasia.