What happens when you have a homozygous mutation on a gene (eg. a swapped base), that is considered pathogenic, but without developing the disease?
It it were a heterozygous mutation I would get it, because we still have at least one healthy/wild-type copy of the gene, so at most the disease will just manifest in a more mild form, but with a homozygous I have no idea how is it possible to NOT develop the disease.
Also, what happens when heterozygous mutations develop the disease? In these cases why does the healthy version of the gene goes "quiet"?
One example is HH caused by HFE gene mutation (mostly C282Y and H63D), and not everyone develops the disease, doesn't matter if they are heterozygous or homozygous.