Children with SCD in Jamaica were more likely to have asthma and more likely to have increased Th2 cytokines (defined as detectable IL-4/undetectable IFN- γ) than local Jamaican age- and ethnically- matched controls while children in the UK with SCD were less likely to have asthma and increased Th2 cytokines than local controls [48]. This evidence concerns the gene IL4 and Schnyder corneal dystrophy.