Cystic fibrosis, Myotonic dystrophy and Thalassemia are

Options

A. Chromosomal disorder
B. Autosomal recessive disorders
C. Mendelian disorders
D. Autosomal dominant disorder

Answer

To answer the question regarding cystic fibrosis, myotonic dystrophy, and thalassemia, we will analyze each disorder and classify them appropriately.

### Step-by-Step Solution:

1. **Identify the Disorders**:
- Cystic fibrosis
- Myotonic dystrophy
- Thalassemia

2. **Classify Cystic Fibrosis**:
- Cystic fibrosis is classified as an **autosomal recessive disorder**. This means that the disorder occurs when an individual has two copies of the recessive allele, one inherited from each parent. It is primarily caused by a mutation in the CFTR gene located on chromosome 7.

3. **Classify Myotonic Dystrophy**:
- Myotonic dystrophy is classified as an **autosomal dominant disorder**. In this case, only one copy of the mutated gene (inherited from one parent) is sufficient to cause the disorder. It is characterized by progressive muscle wasting and weakness.

4. **Classify Thalassemia**:
- Thalassemia is classified as a **sex-linked recessive disorder** (specifically, it is often referred to as X-linked). It involves a defect in hemoglobin production, leading to anemia. Thalassemia can be categorized into alpha thalassemia and beta thalassemia, depending on which part of the hemoglobin chain is affected.

5. **Conclusion**:
- All three disorders (cystic fibrosis, myotonic dystrophy, and thalassemia) are classified as **Mendelian disorders** because they are caused by mutations in single genes and follow Mendelian inheritance patterns.

### Final Answer:
Cystic fibrosis, myotonic dystrophy, and thalassemia are types of **Mendelian disorders**.

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