A defective gene carried on the X chromosome is known as what?

• A. Autosomal Gene
• B. Mitochondrial Gene
• C. Y-linked Gene
• D. X-linked Gene

Answer: (D)

Genes sit on different chromosomes, and where a gene is located affects how it’s inherited. A defective gene on the X chromosome is called an X-linked gene. This pattern means the trait is tied to the X chromosome, which helps explain why many X-linked conditions—such as some color vision defects or hemophilia—often appear more in males, who have only one X, while females have two X chromosomes and may be carriers if only one copy is affected. This stands in contrast to autosomal genes on the non-sex chromosomes, Y-linked genes on the Y chromosome (which affect males specifically), and mitochondrial genes inherited from the mother. So the correct term for a defective gene carried on the X chromosome is an X-linked gene.