Parental recessive allele frequency and recessive survival rate in human genetic disorders

Undetected prenatal losses of homozygous recessives suggest a need for an approach to estimation of parental recessive allele frequency (q) that avoids the observed filial recessive frequency (R) in calculation. This need is met by the equation q = H/(2D + H), in which D and H represent observed filial homozygous dominant and heterozygote frequencies, respectively. Survival (w) of recessive offspring between conception and time of detection can then be estimated with the equation w = 4DR/H².