One of the best known and shocking genetic conditions is albinism. It is a genetic mutation that results in an absence of melanin (cellular pigment) in both the eyes and the skin and hair.
Many parents wonder (usually when they see an albino person) how many possibilities do they have of having an albino baby and that is why we will try to answer this question.
Albinism is a hereditary condition and there are non-albino people who are carriers of the gene that contains the mutation, however it is necessary that both the father and the mother have that gene, because it is a recessive gene (but still being both carriers the children do not have to be albinos). Let's look at some examples to explain how gene inheritance works (considering that "A" is a normal gene and "a" is a gene with the mutation):
- If one of the two parents is not a carrier of the mutated gene (AA) and the other is (Aa), neither of their children will be albino. Taking into account that the children inherit half of the genes of the father and half of the mother, it is only possible that they are AA or Aa. The second (Aa) will be considered a carrier of the gene, although it will not be albino, because it has the dominant gene (A).
- If both parents are carriers of the albinism gene (Aa x Aa) the chances of having an albino child are no longer zero, but 25%. To see it more graphically, the children could be AA (it would not be albino or carrier), Aa (in a 50% chance, since both can inherit the "A" from the father or mother and both can inherit the "a" from one or the other) and aa (albino).
- If one of the parents were albino (aa), the children would also be at a 50% probability if the couple were carriers of the gene (Aa). If the couple was not a carrier, the children would be carriers (Aa).
In Europe, one in 17,000 people is albina. In Africa, where unfortunately there is very little information about it, the ratio varies between 1 per 2,000 and 1 per 5,000, depending on the country (and the treatment that many of them receive is devastating, but this is another issue).
