Rationale: Asthma commonly originates in early life in association with impaired lung function that tracks to adulthood.Objectives: Within the context of a prospective birth cohort study weinvestigated the association between single nucleotide polymorphisms(SNPs) in a disintegrin and metalloprotease 33 (ADAM33) gene andearly-life lung function. Methods: Children were genotyped for 17 SNPs inADAM33. Lung function at age three (n=285) and five years (n=470) wasassessed using plethysmographic measurement of specific airway resistance(sRaw). At age five we also measured FEV1. SNPs were analyzed individuallyusing logistic regression, followed by linkage disequilibrium (LD) mappingto identify the causal locus. Main Results: Carriers of the rare allele ofF+1 SNP had reduced lung function at age three years (p=0.003). When therecessive model was considered, four SNPs (F+1, S1, ST+5, V4) showedassociation with sRaw at age five years (p