Consider a disease allele that is both dominant and lethal to patients that possess it. How could such an allele be passed on from generation to generation? - The disease must leave a small percentage of patients alive, so that some can pass it on to their children. - There must be a medical treatment to sustain life, allowing the patients to reproduce. - The disease must be lethal later in life, after the patient has had children. - The disease must be sex-linked, so that women can be carriers. - The disease must skip generations, like diabetes or albinism.
The disease must be lethal later in life, after the patient has had children.- All dominant lethal disorders, by definition, must strike after childbearing years. If the disorder was lethal to infants, it would never be passed on, as there could be no healthy carriers with a dominant disorder.