Question

A male with haemophilia has children. What is the expected outcome regarding X-linked traits in his offspring?

Options

• None of the offspring will inherit the trait because males cannot pass X-linked traits to their children

• Daughters have a 50% chance of inheriting the trait, and sons have a 50% chance

• All sons will inherit haemophilia from their father

• All daughters will be carriers or affected, while no sons will inherit the trait

Answer 1

An affected male has the genotype XhY (where Xh represents the allele for haemophilia). He passes his X chromosome to all daughters and his Y chromosome to all sons. Therefore, all daughters receive the Xh allele and are at least carriers (if the mother is unaffected) or affected (if the mother carries the allele), while sons receive only the Y chromosome from their father and cannot inherit X-linked traits from him.