Which of the following has autosomal inheritance?
**Core Concept**
Autosomal inheritance refers to the pattern of inheritance where a gene is located on one of the 22 non-sex chromosomes (autosomes) and is inherited in an autosomal dominant or autosomal recessive manner. This type of inheritance is not linked to the sex chromosomes (X and Y) and affects both males and females equally.
**Why the Correct Answer is Right**
Autosomal dominant conditions occur when a single copy of the mutated gene is enough to cause the condition, whereas autosomal recessive conditions require two copies of the mutated gene (one from each parent) to manifest. The inheritance pattern of autosomal conditions is characterized by a 50% chance of passing the mutated gene to each offspring.
**Why Each Wrong Option is Incorrect**
**Option A:** X-linked inheritance is associated with genes located on the X chromosome and affects males more frequently than females due to their having only one X chromosome. This option is incorrect because autosomal inheritance is not linked to the sex chromosomes.
**Option B:** Mitochondrial inheritance is associated with genes located in the mitochondria and is typically maternally inherited. This option is incorrect because autosomal inheritance affects both males and females equally.
**Option C:** Y-linked inheritance is associated with genes located on the Y chromosome and is typically inherited by males from their fathers. This option is incorrect because autosomal inheritance is not linked to the Y chromosome.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that autosomal dominant conditions often have a higher penetrance (i.e., a higher likelihood of manifesting the condition) compared to autosomal recessive conditions, which may have variable expressivity (i.e., varying degrees of severity).
**Correct Answer: D. Autosomal inheritance.**