How are sex-linked disorders inherited?

Sex-linked disorders are inherited through genes present on the sex chromosomes, typically the X chromosome.

Sex-linked disorders are a type of genetic disorder that are passed down through the sex chromosomes. Humans have 23 pairs of chromosomes, one pair of which determines the sex of an individual. These are known as the sex chromosomes, and they come in two types: X and Y. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY).

The majority of sex-linked disorders are X-linked, meaning the faulty or mutated gene causing the disorder is located on the X chromosome. This is because the X chromosome is significantly larger than the Y chromosome and carries many more genes. As a result, if a male inherits a faulty gene on his X chromosome, he will develop the disorder because he does not have a second X chromosome to compensate for the faulty gene. This is why males are more likely to have X-linked disorders.

In contrast, females have two X chromosomes, so even if they inherit a faulty gene on one of their X chromosomes, they may not develop the disorder. This is because they have a second X chromosome that can compensate for the faulty gene. However, they can still be carriers of the disorder and pass it on to their offspring.

Inheritance of these disorders follows specific patterns. For X-linked recessive disorders, a male who has the disorder will pass the gene to all his daughters, who will be carriers, but none of his sons. A female carrier has a 50% chance of passing the gene to her sons, who will have the disorder, and a 50% chance of passing it to her daughters, who will be carriers. For X-linked dominant disorders, a male who has the disorder will pass it to all his daughters but none of his sons, while a female who has the disorder has a 50% chance of passing it to each of her offspring, regardless of their sex.