title: Verification of self-report of zygosity determined via DNA testing in a subset of the NAS-NRC twin registry 40 years later.
abstract: The National Academy of Sciences -- National Research Council (NAS-NRC) twin panel, created nearly 50 years ago, had twin zygosity determined primarily via a similarity questionnaire that has been estimated to correctly classify at least 95% of twins. In the course of a study on the genetics of healthy ageing in the NAS-NRC twins, DNA was collected for genome-wide scanning and zygosity confirmation was examined in 343 participating pairs. The sample was supplemented from two other studies using NAS-NRC twins where one or both co-twins were suspected to have Alzheimer disease or another dementia, or Parkinson's disease. Overall 578 twin pairs with DNA were analyzed. Zygosity assignment for 96.8% (519/536) was confirmed via questionnaire. Among 42 pairs whose questionnaire responses were inconclusive for assigning zygosity, 50% were found to be monozygous (MZ) and 50% were dizygous (DZ). There was some evidence for greater misclassification of presumed DZ pairs in the healthy ageing study where participation favored pairs who were similar in having a favorable health history and willingness to volunteer without any element of perceived risk for a specific disease influencing participation.
authors.affiliation: Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN 46202, USA. treed@iupui.edu
authors.forename: Terry
authors.initials: T
authors.lastname: Reed
authors.forename: Brenda L
authors.initials: BL
authors.lastname: Plassman
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Tanner
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Dick
authors.forename: Shannon A
authors.initials: SA
authors.lastname: Rinehart
authors.forename: William C
authors.initials: WC
authors.lastname: Nichols
mesh_terms: D000328:Adult; D000368:Aged; D004247:DNA / Q000032:analysis*; D005838:Genotype; D006801:Humans; D011795:Surveys and Questionnaires; D014429:Twins, Dizygotic / Q000235:genetics*; D014430:Twins, Monozygotic / Q000235:genetics*
chemical_list: D004247:DNA