(That Word) is an autosomal dominant with variable expression.  One
parent MUST have it, even if it is almost undetectable in the phenotype it
must be present in the genotype.  Generally, 50% of the offspring of a pair
in which one parent is affected will be so affected.  The unaffected
offspring will not be carrying the gene (only recessive genes are hidden) so
they will breed only unaffected offspring.  There are special circumstances
that appear to be exceptions to the rule.  We don't care about them!
Karen (mother of a "special ferret" with [that word again].)
[Posted in FML issue 1289]