Background: Mast cell chymase is a mediator of inflammation and remodeling in the asthmatic lung. Although various studies have examined the association between the -1903 G/A single nucleotide polymorphism (SNP) in the mast cell chymase gene (CMA1) and allergic phenotypes, the results have been inconsistent. A (TG)n(GA)m repeat polymorphism 254 base pairs downstream of CMA1 has been reported in adult
asthmatics. We investigated the relationship between these CMA1 genetic variants and childhood asthma in Egyptian children.

Methods: A case-control study was undertaken in 15 children (6-10 years old) with bronchial asthma enrolled consecutively during exacerbation and 15 age-matched and sex-matched nonasthmatic control subjects. Genotyping was performed by polymerase chain reaction (PCR) restriction fragment length polymorphism to search for polymorphisms in the CMA1 gene promoter region (-1903 G/A) and PCR amplification followed by sequencing to detect the (TG)n(GA)m repeat 254 base pairs downstream of the gene.

Results: Our data showed a positive association between the CMA1 -1903 G/A SNP and asthma in children. The G allele was detected in 70% of patients while the A allele was more frequent in the controls (83.3%). Concerning the (TG)n(GA)m repeat, allele 39 was only present in asthmatics while allele 37 was more common in controls.

Conclusion: We report the association of the -1903 G/A CMA1 SNP and (TG)n(GA)m repeat polymorphism with bronchial asthma in a group of Egyptian children. These polymorphisms are possible determinants of asthma susceptibility and may be involved in regulating immunoglobulin E levels.

Key words: Alleles. Asthma. Children. Chymase gene. Immunoglobulin E. (TG)n(GA)m repeat polymorphism. Restriction fragment length polymorphism. Single nucleotide polymorphism.