Sensitivity of transmission probabilities to paternity exclusion in segregation analysis

Paternity exclusions are known to be common in Western countries and are yet neglected in segregation analysis because it is almost impossible to check it systematically on a large family sample. We had the opportunity of observing the sensitivity of segregation analysis parameters to a paternity exclusion in analyzing 34 families for a simple Mendelian trait, the acetylator phenotype. We found that only one family, with proven paternity exclusion, was responsible for a strong rejection of Mendelian transmission probabilities (P much much less than 0.001).