Cystic fibrosis is a/ an

Options

A. sex - linked recessive disorder
B. autosomal dominant disorder
C. autosomal recessive disorder
D. sex linked dominant disorder

Answer

### Step-by-Step Solution:

1. **Understanding Cystic Fibrosis**:
- Cystic fibrosis is a genetic disorder that primarily affects the lungs and digestive system. It is caused by mutations in the CFTR gene.

2. **Identifying the Type of Disorder**:
- To classify cystic fibrosis, we need to determine whether it is sex-linked or autosomal, and whether it is dominant or recessive.

3. **Analyzing the Options**:
- **Option 1: Sex-linked recessive disorder**: This type of disorder is typically associated with genes on the X chromosome. Examples include hemophilia and color blindness. Cystic fibrosis does not fit this category.
- **Option 2: Autosomal dominant disorder**: In this case, only one copy of the mutated gene is sufficient to cause the disorder. Examples include Huntington's disease. Cystic fibrosis does not fit this category either.
- **Option 3: Autosomal recessive disorder**: This means that two copies of the mutated gene (one from each parent) are required for the individual to express the disorder. Cystic fibrosis is indeed classified as an autosomal recessive disorder.
- **Option 4: Sex-linked dominant disorder**: This type of disorder is also linked to the X chromosome but requires only one copy of the mutated gene. An example is vitamin D-resistant rickets. Cystic fibrosis does not fit this category.

4. **Conclusion**:
- Based on the analysis, cystic fibrosis is classified as an **autosomal recessive disorder**. Therefore, the correct answer is **Option 3**.