Li HF, et al. - In this systematic review and meta-analysis of 63 case-control studies with 13,280 asthma patients and 13,340 controls, researchers focused on asthma susceptibility in relation to the presence of ADAM33 variants. Using online electronic databases, eligible studies published between January 2000 and June 2018 were retrieved. A possible contribution of T2, Q1 and F + 1 polymorphisms of ADAM33 gene to asthma risk was suggested. Asians carriers of alleles and genotypes of T2, Q1 and F + 1 polymorphisms were susceptible to asthma; V4 polymorphism was related to asthma among Caucasian populations, as seen in subgroup analysis by ethnicity. In subgroup analysis by ages, they found an association of T2, F + 1 and ST + 4 polymorphisms with childhood asthma; Q1 and V4 polymorphisms were linked with asthma risk in adults. Compared with the controls, only the G allele of ADAM33 T1 polymorphism was found to be related to asthma severity, in the subgroup analysis by asthma severity.