Objective: To investigate the clinical manifestation and mutation characteristics of ATM gene in Chinese patients with ataxia-telangiectasia (AT).
Methods: Sequence variants of the entire coding exons of ATM gene were tested using polymerase chain reaction (PCR), reverse transcription-polymerase chain reaction (RT-PCR), polyacrylamide gel electrophoresis (PAGE) and DNA direct sequencing in two Chinese patients clinically diagnosed as AT.
Results: The clinical characteristics of two AT patients were progressive cerebellar ataxia with ages at onset of childhood, ocular-cutaneous telangiectasia and recurrent pulmonary infection due to immuno-deficiency; the serum alpha fetoprotein (AFP) levels were higher than normal, the serum immunoglobin IgA and IgG levels were lower than normal; brain MRI showed cerebellar atrophy, brain SPECT showed cerebellar regional cerebral blood flow (rCBF) hypoperfusion to a certain degree. Totally three nucleotide changes were identified. A missense mutation of G1346C in exon 11, which was a homozygotic mutation, was identified in one patient; a nonsense mutation of G610T in exon 6 combined with a missense mutation of C6679T in exon 47, which was a compound heterozygotic mutation, were identified in the other patient. They were co-segregated with the disease and were localized within the functional domain of ATM gene.
Conclusion: We have made gene diagnoses for two Chinese AT patients, in which three novel ATM gene mutations were identified.