Abstract: 　Objective　To investigate the pathogenicity of novel mutations in the ATM gene that cause ataxia telangiectasia. Methods　The clinical data and gene detection results of two unrelated autistic telangiectasia pedigree family were analyzed, and new mutation sites were verified by Sanger sequencing. Results　Compound heterozygous mutations of c.7627delA and c.8385-8394del were found in the proband of family 1 which were inherited from the parents, and compound heterozygous mutation c.2638delG and c.2921+1G>C were found in the proband of family 2. In family 2, c.2638delG is inherited from the mother, while the paternal sample is not available. These four novel mutations have not been documented in HGMD database. In silico analysis it predicted the four mutations were pathogenic. Conclusion　The novel mutations in ATM gene were confirmed to be the cause of the two unrelated ataxia telangiectasia families.

Key words: 　ataxia telangiectasia;　ATM gene;　new mutation;　genotype