between 10 and 15 years of age, and differs from A–T by the absence of telangiectasia and oculomotor apraxia, a normal alpha fetoprotein, and the frequent presence of scoliosis, absent tendon reflexes, and abnormal features on the EKG. Individuals with FA manifest difficulty standing in one place that is much enhanced by closure of the eyes (Romberg sign) that is not so apparent in those with A–T – even though those with A–T may have greater difficulty standing in one place with their eyes open. There are other rare disorders that can be confused with A–T, either because of similar clinical features, a similarity of some laboratory features, or both. These include: Ataxia–oculomotor apraxia type 1 (AOA1) Ataxia–oculomotor apraxia type 2 (AOA2 also known as SCAR1) Ataxia–telangiectasia like disorder (ATLD) Nijmegen breakage syndrome (NBS) Ataxia–oculomotor apraxia type 1 (AOA1) is an autosomal recessive disorder similar to A–T in manifesting increasing problems with coordination and oculomotor apraxia, often at a similar age to those having A–T. It is caused by mutation in the gene coding for the protein aprataxin. Affected individuals differ from those with A–T by the early appearance of peripheral neuropathy, early in their course manifest difficulty with initiation of gaze shifts, and the absence of ocular telangiectasia, but laboratory features are of key importance in the differentiation of the two. Individuals with AOA1 have a normal AFP, normal measures of immune function, and after 10–15 years have low serum levels of albumin. Genetic testing of the aprataxin gene can confirm the diagnosis. There is no enhanced risk for cancer. Ataxia–oculomotor apraxia type 2 (AOA2) is an autosomal recessive disorder also similar to A–T in manifesting increasing problems with coordination and peripheral neuropathy, but oculomotor apraxia is present in only half of affected individuals. Ocular telangiectasia do not develop. Laboratory abnormalities of AOA2 are like A–T, and unlike AOA1, in having an elevated serum AFP level, but like AOA1 and unlike A–T in having normal markers of immune function. Genetic testing of the senataxin gene (SETX) can confirm the diagnosis. There is no enhanced risk for cancer. Ataxia–telangiectasia like disorder (ATLD) is an extremely rare condition, caused by mutation in the hMre11 gene, that could be considered in the differential diagnosis of A–T. Patients with ATLD are very similar to those with A–T in showing a progressive cerebellar ataxia, hypersensitivity to ionizing radiation and genomic instability. Those rare individuals