X-linked Recessive Alleles and their sex-linked features

X-linked Recessive Allele is the recessive form of a gene residing on the X chromosome. In this post, we will discuss the sex-linked features determined by X-linked Recessive Alleles.

X-linked Recessive Alleles and their sex-linked features

In the next section, we have discussed X-linked Recessive Alleles and their sex-linked features.

Sex-linked features determined by recessive alleles on the X chromosome share the following characteristics:

1. Sex-linked features determined by X-linked Recessive Allele are much more common among males (because a female must inherit the recessive alleles on both of her X chromosomes, whereas a male must inherit the recessive allele on his single X chromosome)
2. Affected males inherit the allele from their mother [as the allele is X-linked and a male gets the X chromosome from his mother]
3. Affected females inherit one allele from each parent [Females have two X chromosomes and as the allele is X-linked recessive, hence both the X chromosomes of an affected female must have this allele. A female receives one X chromosome from each parent. That means the father of an affected female must have this allele on his X chromosome (so the father must be affected). And the mother of the affected female must have this X-linked recessive allele, at least, on one of her two X chromosomes.]
4. Females who are heterozygous for the condition are called carriers. This means if only one of the two X chromosomes of a female has this allele, then the female is a carrier.
5. Sex-linked features determined by X-linked Recessive Allele may ‘skip’ a generation and then appear in the males only.

Related Posts:

X-linked recessive disorders are more common in males – why?

Alleles and Genotypes for human blood groups – multiple allelism in ABO