What is one of the types of inheritance patterns of human diseases?

• A. X-linked recessive
• B. Imprinted inheritance
• C. Mitochondrial inheritance
• D. Epigenetic inheritance

Answer: (A)

One of the key inheritance patterns of human diseases is X-linked recessive inheritance. This pattern occurs when a gene responsible for a disease is located on the X chromosome, which is one of the two sex chromosomes in humans. In this type of inheritance, males, who have only one X chromosome (paired with a Y chromosome), are more severely affected by recessive mutations on the X chromosome because they lack a second X chromosome that could potentially carry a normal allele.

For females, who have two X chromosomes, the presence of one normal allele can mask the effects of a recessive mutation on the other X chromosome, leading them to be carriers rather than manifesting the disease. Conditions such as hemophilia and Duchenne muscular dystrophy exemplify X-linked recessive inheritance, where males are predominantly affected, while females may be carriers and display milder symptoms or none at all.

The other inheritance patterns mentioned—imprinted inheritance, mitochondrial inheritance, and epigenetic inheritance—also play roles in genetics but represent different mechanisms or effects that do not specifically classify as X-linked recessive. Imprinted inheritance refers to genes that are expressed in a parent-of-origin-specific manner, mitochondrial inheritance relates to maternally inherited traits carried in mitochondrial DNA, and epigenetic