12 ms·
The interesting thing about sickle cell anaemia is that you get it if both copies of the gene are abnormal, you get the disease, but if just one of them is abno
by FreeFull 8y ago
The interesting thing about sickle cell anaemia is that you get it if both copies of the gene are abnormal, you get the disease, but if just one of them is abnormal you don't get the disease but still get the resistance to malaria.
- DoreenMichele 8y agoCystic fibrosis (CF) is also homozygous recessive. Presumably, both disorders developed for the same reason: One copy of the gene is protective, but not crippling. Two copies are crippling. So those with one copy had higher survival rates when epidemics of certain diseases hit. This meant that more of their children survived, even though some of their children were born with terrible impairment and worse survival rates. People with CF tend to not reproduce. In fact, 97 percent of males with CF lack a vas deferens, making them effectively sterile. It's mostly the carriers who create new people with CF. Some of them had no idea they were carriers until they had a child with CF.