title: Derivation of new mathematic formulas for determining whether a D-positive father is heterozygous or homozygous for the D antigen.
abstract: OBJECTIVE
  This article derives new mathematic formulas to calculate the probability that the husband of a D-negative woman is heterozygous for the D antigen.
  
  
  METHODS
  Current published formulas and tables that estimate this probability are biased in that they incorrectly assume that the father is randomly selected from the general population. With Bayes' theorem, new formulas were derived to eliminate this bias.
  
  
  RESULTS
  The probability of the husband being homozygous or heterozygous for the D antigen can be expressed as a function of the number of previous D-positive children. If he has any D-negative children, he is an obligate heterozygote.
  
  
  CONCLUSIONS
  Previously published formulas and tables that estimate the likelihood of the father being heterozygous or homozygous at the D locus should no longer be used in the obstetric setting.
authors.affiliation: Department of Pathology, Kaiser Permanente, Los Angeles, CA 90034.
authors.forename: M H
authors.initials: MH
authors.lastname: Kanter
mesh_terms: D044383:Black People / Q000235:genetics; D005220:Fathers; D006580:Genetic Carrier Screening / Q000379:methods*; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D008297:Male; D010641:Phenotype; D011336:Probability; D012204:Rh-Hr Blood-Group System / Q000235:genetics*; D044465:White People / Q000235:genetics
chemical_list: D012204:Rh-Hr Blood-Group System