Sex Chromosome Linked Inheritance

Sex Chromosome Linked Inheritance

Sex chromosome-linked inheritance, also known as X-linked inheritance, involves genes located on the X and Y sex chromosomes.

 In humans, females have two X chromosomes (XX), while males have one X and one Y chromosome (XY).

 Inheritance Patterns:

a. X-Linked Recessive Inheritance:

- X-linked recessive traits are more common in males because they have only one X chromosome.

- For a male to express an X-linked recessive trait, he needs only one copy of the recessive allele.

- Females must have two copies of the recessive allele to express the trait (homozygous recessive).

- Examples: Hemophilia, colour blindness.

 b. X-Linked Dominant Inheritance:

- X-linked dominant traits are less common and can affect both males and females.

Affected males transmit the trait to all their daughters but not to their sons.

- Affected females can transmit the trait to both sons and daughters.

- Examples: Rett syndrome, vitamin D-resistant rickets.