During recent years, considerable efforts, especially genome-wide association studies (GWAS), have been conducted to identify genetic factors underlying ND, with several widely accepted successes, including the identification of the importance of AChR subunit gene clusters on chromosomes 15 (CHRNA5/A3/B4)11–16 and 8 (CHRNB3/A6)17–20 and the genes encoding nicotine-metabolizing enzymes on chromosome 19 (CYP2A6/A7)19, 21–23. This evidence concerns the gene CHRNB3 and Norrie disease.