Summary Level Data: deCODE Genetics Study on Genes Contributing to Nicotine Dependence in Humans

A genome-wide association study on smoking behavior and nicotine dependence in Icelandic smokers, assessed by the number of cigarettes smoked per day, smoking initiation and degree of dependence on nicotine. The number of cigarettes smoked per day was ascertained through questionnaires given to individuals participating in multiple disease projects at deCODE Genetics (n=16,483). Smoking initiation was analyzed by comparing those that have ever smoked (n=16,483) versus those that have never smoked (n=21,667). The nicotine dependence analysis included 3,435 nicotine dependent cases (score 4 or higher on Fagerstrom Test for Nicotine Dependence (FTND) or endorsement of at least three of the seven Diagnostic and Statistical Manual of Mental Disorders 4th edition (DSM-IV) criteria) and 3,344 low-quantity smokers as controls.]]>
A study seeking sequence variants associating with nicotine dependence. Chip data was on the Illumina 300k set of SNP.A study seeking sequence variants associating with smoking initiation. Chip data was on the Illumina 300k set of SNPs. Ever smokers are treated
as cases and never smokers as controls.The number of cigarettes smoked per day was ascertained through questionaires given to individuals participating in multiple disease projects at deCODE genetics. Current smokers were asked how much they currently smoke and previous smokers were asked how much they smoked before quitting. Smokers were given a choice between four categories: 0-9 cigaretes per day, 10-19 cigarettes per day, 20-29 cigarettes per day and 30 or more cigarettes per day.Individuals showing low genotype yield were excluded from the analysis (<98% call rate).]]>