NRXN3 and chronic obstructive pulmonary disease: SNP annotation revealed that some genetic variants that influenced the association of the exposure variables with asthma and COPD were missense variants in several genes, including the evolutionarily highly conserved gene, SLC39A8 (rs13107325; C/A/T allele), and POC5 (rs2307111; T/A/C allele), as well as intronic variants in FTO (rs56094641; A/G/T allele) and NRXN3 (rs10146997; A/G allele).