Consider the following disorders :
Haemophilia, sickle cell anemia , cystic fibrosis, Thalassemia, phenylketonuria, polydactyly, kleinfelter's syndrome, Turner's syndrome
How Many of the above disorders are Mendelian Autosomal disorders

Options

A. One
B. Two
C. Five
D. Eight

Answer

To determine how many of the listed disorders are Mendelian autosomal disorders, we need to classify each disorder based on its inheritance pattern.

### Step-by-Step Solution:

1. **Identify the Disorders**: We have the following disorders to analyze:
- Hemophilia
- Sickle Cell Anemia
- Cystic Fibrosis
- Thalassemia
- Phenylketonuria
- Polydactyly
- Klinefelter's Syndrome
- Turner's Syndrome

2. **Classify Each Disorder**:
- **Hemophilia**: This is a sex-linked disorder (specifically X-linked), not an autosomal disorder.
- **Sickle Cell Anemia**: This is an autosomal recessive disorder.
- **Cystic Fibrosis**: This is also an autosomal recessive disorder.
- **Thalassemia**: This is an autosomal recessive disorder.
- **Phenylketonuria (PKU)**: This is an autosomal recessive disorder.
- **Polydactyly**: This is an autosomal dominant disorder.
- **Klinefelter's Syndrome**: This is a chromosomal disorder (47,XXY), not an autosomal disorder.
- **Turner's Syndrome**: This is also a chromosomal disorder (45,X), not an autosomal disorder.

3. **Count the Mendelian Autosomal Disorders**:
- From the classification, the Mendelian autosomal disorders are:
- Sickle Cell Anemia
- Cystic Fibrosis
- Thalassemia
- Phenylketonuria
- Polydactyly

Therefore, there are **5 Mendelian autosomal disorders**.

4. **Final Answer**: The answer to the question is **5**.