Question

A rare condition known as adermatoglyphia leads to such smooth fingertips that the individual has no fingerprints. It has been dubbed the "immigration delay disease" because sufferers have such a hard time entering foreign countries. Recently the cause has been traced to a point mutation in the very first nucleotide of an intron. The condition also leads to less hand sweat than the average person and researchers think that the gene might help skin cells fold over one another early in fetal development. This mutation is dominant to the wild type allele. A woman with this mutation marries a man with the same mutation. Why might it be difficult to calculate the probability they will have a child with fingerprints (consider all of the genotypes and phenotypes of potential children and the possible contribution of the gene to early fetal development)?