An albino girl gets married to a normal boy, What are the chances of their having an affected child and what are the chances of their children being carriers ?
The question says an albino girl marries a normal boy. So the girl has albinism, which is autosomal recessive. That means she must have two recessive alleles (aa). The boy is normal, but he could be either homozygous dominant (AA) or a carrier (Aa). However, since the question states he's "normal," unless there's more context, we might assume he's not a carrier. Wait, but if the boy is from a population where albinism is rare, the chance he's a carrier is low. But maybe in this case, we need to consider that the boy is not a carrier because he's phenotypically normal and there's no mention of a family history.
So, if the mother is aa (albino) and the father is AA (normal), all their children would get one a from the mother and one A from the father. So all children would be Aa carriers. Therefore, the chance of an affected child is 0%, and all children are carriers. But wait, the options aren't given here, so maybe the correct answer is 0% affected, 100% carriers. Let me check the standard Mendelian inheritance for this scenario.
Yes, in an autosomal recessive condition, if one parent is affected (homozygous recessive) and the other is homozygous dominant, all offspring are carriers. There's no chance of being affected because the child needs two recessive alleles. So the affected chance is 0, carrier is 100%. So the correct answer should be 0% affected and 100% carriers. Therefore, the correct answer is the option that states that.
**Core Concept**
Albinism is an autosomal recessive disorder caused by mutations in genes responsible for melanin synthesis. Affected individuals (homozygous recessive) have two defective alleles (aa), while carriers (heterozygous) have one normal and one defective allele (Aa).
**Why the Correct Answer is Right**
The albino girl (aa) must pass one *a* allele to all offspring. The normal boy, assuming he is homozygous dominant (AA), will pass only *A* alleles. All children will inherit *Aa*, making them carriers. Since no child receives two *a* alleles, none will be affected. This follows Mendelian inheritance principles for autosomal recessive traits.
**Why Each Wrong Option is Incorrect**
**Option A:** Likely suggests 25% affected, 50% carriers—this applies if both parents are carriers (Aa x Aa), not when one is affected (aa) and the other is AA.
**Option B:** May propose 50% carriers—incorrect because all offspring inherit one *a* allele, making 10