A novel human catalase mutation (358 T-->del) causing Japanese-type acatalasemia.

Japanese-type acatalasemia is characterized by the almost total loss of catalase activity in red cells and is often associated with ulcerating oral lesions. A splicing mutation in intron 4 of catalase gene has so far been a sole disease-causing mutation found in Japanese-type acatalasemic patients. We report here a novel single base deletion in the catalase gene causing Japanese-type acatalasemia. The patient was a 72 year-old Japanese male. His maternal grandmother and his father were first cousins. Molecular analysis using non-RI PCR-SSCP analysis combined with direct sequencing revealed a deletion of the 358th thymine in exon 4 of the patient's catalase gene. The proband was a homozygote and his mother and his three children were heterozygotes for this mutation. The frame shift caused by the nucleotide deletion should alter the downstream amino acid sequence and introduce a new termination codon TGA 43 bp 3' to the mutation. Although the truncated peptide chain consisted of 133 amino acid residues might be translated in the patient's tissue, such an aberrant protein is expected to be extremely unstable and have no catalytic function at all. Our results suggest that Japanese-type acatalasemia is heterogeneous.