- Study Description
Ascertainment: Families were ascertained through panels of adult Australian twins, and a sample of spouses of Australian twins. Families with at least one offspring who was identified as a current or former smoker in an earlier survey. Screening telephone interviews were conducted with index cases to provide confirmation of a history of heavy cigarette smoking, to obtain confirmation of a history of heavy cigarette smoking, and to obtain additional information on the history of cigarette use and the survival status of other family members, and their full siblings and parents. Index cases were the affected spouse of a twin, or the affected twin from pairs discordant for a history of heavy smoking, or a randomly chosen twin from pairs where both have a history of regular smoking (i.e., has smoked at least 100 cigarettes lifetime), and at least one live biological parent to identify sibships with at least one affected sib pair (ASP) concordant for heavy smoking, and at least one living parent. If permission was granted by the index case, eligible family members were contacted and invited to provide a blood sample and to complete a telephone diagnostic interview. In families with just one available biological parent, and additional unaffected sibling who had never smoked on a regular basis (i.e., has smoked fewer than 100 cigarette lifetime, but has experimented with cigarettes once or twice) was included (when available) to help compensate for the loss of information due to missing parental phenotypes. (Target N=400 Australian families with approximately 600 ASPs; and 600 TDT trios comprised of a nicotine dependent index case and both biological parents). Diagnostic Assessment: The telephone diagnostic interview assessed DSM-IV and modified DSM-IIIR diagnoses (i.e., without time clustering) for nicotine dependence, alcohol and other drug dependence and abuse, major depression, and childhood conduct disorder. Most diagnostic assessments were based on the SSAGA/SSAGA-II, developed for the multi-site gene-mapping alcoholism study (the Collaborative Study on the Genetics of Alcohol. An exception was the tobacco section, which was developed directly from the CIDI and DIS (as the original SSAGA did not include a diagnostic section on nicotine dependence).
In version 2 of this study, a text file containing 7704 SNPs with large allele frequency discrepancy as compared to 1000 Genomes is included. Users have the option to exlude these 7704 SNPs.
- Authorized Access
- Publicly Available Data (Public ftp)
- Study Inclusion/Exclusion Criteria
An affected full sibling pair design, with the inclusion of any additional affected full siblings in the family, both biological parents (when available), and (if one or both parents are unavailable for study) unaffected full siblings who have been exposed to nicotine (i.e., have smoked at least once or twice), but never became regular smokers (i.e., smoked fewer than 100 cigarettes in their life) to help compensate for the loss of information due to missing parental phenotypes. This design permits affected sib pair analyses and TDT (including sib-TDT) analyses.
Australia has a large national twin panel in which smoking data were collected prospectively over a period of many years (from 1980-82 onwards). Heavy smoking cases were identified from these panels. In the case of MZ twin pairs concordant for heavy smoking, one twin, with preference given to a twin who also met criteria for nicotine dependence, was selected as the index case, and the MZ co-twin can be discarded from traditional analyses.
- Molecular Data
Type Source Platform Number of Oligos/SNPs SNP Batch Id Comment Targeted Genotyping BioRealm Smokescreen Genotyping Array N/A N/A
- Study History
The Smokescreen® Genotyping Array by BioRealm® was created with support of a NIDA SBIR contract. The chip consists of an Affymetrix backbone with over 800,000 SNPs. The chip covers 98% of common genetic variation in 1000 nominated addiction genes. The chip contains 296,000 markers from African, East Asian, and European populations giving 66% coverage for people of African Ancestry, 82% for people of East Asian Ancestry, and 91 % for people of European ancestry. In addition, 20,000 markers from expert nominations for genes posited to be associated with substance abuse and co-morbid disorders are also included on the chip. In addition, included in the array are more than 11,000 markers in the nicotine acetylcholine receptor gene clusters and nicotine metabolizing genes. There are greater than 16,000 markers for related co-morbidities and diseases.
The samples will be released separately by contributing investigators, with ultimately a total of approximately 50,000 targeted.
- Selected Publications
- Diseases/Traits Related to Study (MeSH terms)
- Links to Related Resources
- Authorized Data Access Requests
- Study Attribution
- Pamela Madden, PhD. Washington University, St. Louis, MS, USA.
- DA12854. National Institute on Drug Abuse, National Institutes of Health, Bethesda, MD, USA.
- Principal Investigator