A disintegrin and metalloproteinase 33 (ADAM33) gene polymorphism association with asthma in Egyptian children

A disintegrin and metalloproteinase-encoding gene (ADAM33), was recently identified as an asthma susceptibility gene. ADAM33 protein is expressed in smooth muscle cells of bronchi and pulmonary fibroblasts, playing a major role in airway remodeling. Earlier studies, have mostly confirmed a link between ADAM33 and asthma as well as bronchial hyperresponsiveness. This work studied a group of Egyptian asthmatic children for 3 ADAM33 single nucleotide polymorphisms (SNPs), previously identified as putative risk alleles: T1 G > A(rs2280091), T2 A > G(rs2280090), V4 G > C(rs2787094) using Polymerase Chain Reaction – restriction fragment length polymorphism (PCRRFLP) with emphasis on their relation to clinical (severity, smoking, family history, and atopic manifestations) and laboratory data (Ig Immunoglobulin E (Ig E) level and absolute eosinophilia) and pulmonary functions. Sixty (3–12 years old) asthmatic children and 32 matched controls were recruited. The genotype distribution for the SNPs showed no significant difference between the patients and the controls. A higher frequency of the (AA) genotype of T1 polymorphism was found in controls (75%) than in patients (41%), while the (AG) variant was higher in cases (46.6%) than in controls (21.9%) but with no statistically significant difference. Also the (GG) genotype was higher in cases (11.6%) than in controls (3.1%) but with no statistical significance. The allelic frequencies of T1 showed a higher (A) allele in controls (85.93%) than cases (65%) and higher (G) allele in cases (35%) than controls (14.06%), showing a high significant difference. No correlation was found between (T1, T2, and V4) and the demographic, clinical and laboratory parameters, except SNP T1 showing a positive correlation with Ig E level, and SNP V4 showing a positive correlation with passive smoking as a precipitating factor and borderline significance with absolute eosinophilia. In conclusion, no significant association was detected between these SNPs and asthma susceptibility in this study.