title: The misclassification of family history status in studies of children of alcoholics.
abstract: OBJECTIVE
  The search for genetic and phenotypic markers associated with future alcoholism risk often centers on comparisons of children of alcoholics and controls. Such studies require large samples to compensate for the rate of expression of alcoholism in less than half of children of alcoholics, the importance of environmental influences, the complex types of inheritance likely to be involved and the lack of precision of many of the measurements used. An additional problem is the change in family history status over time.
  
  
  METHODS
  This study uses personal interviews with subjects and an additional informant during a 9.3-year follow-up of 223 men to demonstrate the impact of the problem of family history misclassification.
  
  
  RESULTS
  On follow-up, 7% of the men who had been originally classified as family history negative (FHN) were found to have a close relative who developed alcoholism during the follow-up period, and another 6% had gained knowledge of a preexisting alcohol use disorder in their relatives during the interval since testing. Also, 5% of the 223 men had originally been identified as sons of alcoholics but were found to have been incorrectly categorized based on more thorough information at follow-up.
  
  
  CONCLUSIONS
  These findings underscore the conclusion that relatively large samples are required in this research to overcome the minimum of a 7% error rate in family history assignment likely to occur from the future development of alcoholism in the family of family history negative subjects along with additional errors in reporting or interpreting original histories.
authors.affiliation: Department of Psychiatry, Veterans Affairs Medical Center, San Diego, California 92161-2002, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Schuckit
authors.forename: J L
authors.initials: JL
authors.lastname: Klein
authors.forename: G R
authors.initials: GR
authors.lastname: Twitchell
mesh_terms: D000293:Adolescent; D000328:Adult; D000437:Alcoholism / Q000145:classification / Q000235:genetics* / Q000523:psychology; D015982:Bias; D002140:California; D016241:Child of Impaired Parents / Q000145:classification* / Q000523:psychology; D005819:Genetic Markers / Q000235:genetics; D006801:Humans; D008297:Male; D010641:Phenotype; D012931:Social Environment
chemical_list: D005819:Genetic Markers