Question

A man is heterozygous for albinism as well as sickle cell anaemia. What portions of his gametes will contain genes for both diseases?
A.$\dfrac{1}{4}$
B.$\dfrac{2}{4}$
C.$\dfrac{1}{3}$
D.$\dfrac{1}{8}$

Answer 1

Sickle cell anaemia is an autosomal recessive disease, which means it only occurs when both the maternal and paternal copies of the HBB gene are faulty.
In other words, if a person inherits only one copy of the faulty HBB gene from either their mother or father, they would get sickle cell trait rather than sickle cell anaemia. People with sickle cell trait normally have no symptoms or concerns, but the defective gene can be passed down to their children.

Complete answer:
Option A: Both of the disorders listed are inherited in an autosomal recessive fashion. The man's genotype would be AaSs if he is heterozygous for both Albinism and Sickle Cell Anemia. AS, As, aS, as are the sorts of gametes he produces. Just "as" gametes have genes for both disorders, and "as" gametes make up only $\dfrac{1}{4}$ of the total.
So option A is correct.
Option B: If the guy is tested and his haemoglobin levels are normal, the children are not at danger of developing sickle cell disease. If he also has sickle cell trait, each of the offspring has a $25\%$ ($1$ in $4$) risk of inheriting both parents' sickle cell genes and developing sickle cell illness.
So option B is not correct.
Option C: Both of the illnesses mentioned are autosomal recessive in nature. If the individual is heterozygous for both Albinism and Sickle Cell Anemia, his genotype will be AaSs. As are the kind of gametes he produces: AS, AS, aS. Both illnesses have genes in "as" gametes, which account for only $\dfrac{1}{4}$ of the total.
So option C is not correct.
Option D: If both parents have sickle cell trait, the child has a $25\%$ chance of getting sickle cell anaemia and a $50\%$ chance of getting sickle cell trait. There's also a $25\%$ risk that neither copy of the mutant gene will be passed down to the child.
So option D is not correct.

So option A is the correct answer.

Note:
Depending on the genetic aetiology of albinism, different kinds of albinism can have varied inheritance patterns. The eyes, hair, and skin are all affected by oculocutaneous albinism (OCA). Ocular albinism (OA), a considerably less frequent condition, affects mostly the eyes, with skin and hair that is similar to or slightly lighter than that of other family members.
OCA has an autosomal recessive inheritance pattern. This suggests that a person must have two mutations to have OCA. Each numbered chromosome and the genes on it are generally inherited in two copies, one from the father and the other from the mother.