Carrier Risk Calculations for Recessive Diseases when all the Mutant Alleles are not Detectable

There are certain recessive diseases in which some of mutations causing the disease, can be detected using the genetic probabilities. For counseling purposes, the probability that, a consultand known not to have a detectable mutation, a carrier needs to be calculated with as much accuracy as possible. A method for the carrier risk calculation is proposed, which is based on information on the parents, one or two sibs and one or two children as well as on the spouse of the consultand in terms of positive or negative test results only, since genotype configurations for all of them may not be available in practice. For a particular disease, the carrier risk is calculated by its incidence and the proportion of the mutations that are detectable, the table once produced can be used for any family of the types included.