X-linked inheritance is a type of sex-linked inheritance in which a particular trait is carried on the X chromosome
The correct answer and explanation is:
Correct Answer: True
Explanation:
X-linked inheritance is indeed a form of sex-linked inheritance where the gene responsible for a specific trait or disorder is located on the X chromosome. Humans have 23 pairs of chromosomes, and one pair determines biological sex: females have two X chromosomes (XX) while males have one X and one Y chromosome (XY). When a gene is carried on the X chromosome, its inheritance pattern follows certain rules because of the difference in sex chromosomes between males and females.
Males are hemizygous for the X chromosome, meaning they have only one copy. If that single X chromosome carries a gene mutation, the trait or disorder will be expressed because there is no second X chromosome to compensate. For example, hemophilia A and red-green color blindness are classic X-linked recessive conditions. If a male inherits a defective gene from his mother’s X chromosome, he will show the trait. In contrast, females have two X chromosomes, so if one X chromosome carries a defective gene and the other X has a normal copy, the normal gene can often mask the effect of the defective one. Females are therefore usually carriers if the inheritance is recessive. A carrier female has a 50 percent chance of passing the gene to her offspring. Sons who inherit it will express the trait; daughters who inherit it will become carriers like their mother.
X-linked dominant traits are less common but can also occur. In these cases, one altered copy of the gene on the X chromosome is enough to cause the trait in both males and females, though severity can vary. An example is Rett syndrome. The unique pattern of X-linked inheritance explains why some conditions appear more frequently in males than females and why pedigree charts of X-linked traits often show affected males linked through carrier females. Understanding this helps in genetic counseling and family planning.