The pattern of inheritance in the give pedigree chart
## Core Concept
The question involves analyzing a pedigree chart to determine the pattern of inheritance of a particular trait or disease. This requires understanding the fundamental principles of genetics, including autosomal dominant, autosomal recessive, X-linked dominant, X-linked recessive, and Y-linked inheritance patterns.
## Why the Correct Answer is Right
The correct answer, , indicates an X-linked recessive pattern of inheritance. This pattern is characterized by the following features:
- The trait or disease appears more frequently in males than in females.
- Affected males do not pass the trait to their sons but all their daughters are carriers.
- Female carriers have a 50% chance of passing the trait to each son, who will be affected, and to each daughter, who will be a carrier.
## Why Each Wrong Option is Incorrect
**Option A:** - This option does not match the description of X-linked recessive inheritance. Without a specific description, we can infer it's incorrect based on the elimination and characteristics of other patterns.
**Option B:** - This option suggests a different pattern of inheritance. If it represents an autosomal dominant pattern, for example, we would expect an equal distribution of the trait among males and females and a direct parent-to-offspring transmission.
**Option C:** - Similarly, this option does not fit the X-linked recessive pattern. If it represents an autosomal recessive pattern, we would see affected individuals have unaffected parents who are carriers, and there would be no sex predilection.
## Clinical Pearl / High-Yield Fact
A key point to remember is that X-linked recessive diseases, such as hemophilia A and B and Duchenne muscular dystrophy, are more common in males. This is because males have only one X chromosome; thus, a single mutation in a gene on the X chromosome is enough to cause the disease.
## Correct Answer Line
**Correct Answer: C.**