The genetic disoders in which the patients have one chromosome less than normal humans are :

Options

A. Down's syndrome
B. Alpha Thalassemia
C. Turner's syndrome
D. Klinefeter's syndrome

Answer

To solve the question regarding genetic disorders where patients have one chromosome less than normal humans, we can follow these steps:

### Step 1: Understand Normal Chromosome Count
Normal humans have a total of 46 chromosomes, which consist of 44 autosomes and 2 sex chromosomes (XX or XY).

**Hint:** Remember that the normal chromosome count is 46, which is the baseline for comparison.

### Step 2: Identify the Genetic Disorders Listed
We need to analyze the genetic disorders mentioned in the question to see if they involve a reduction in chromosome number.

**Hint:** List the genetic disorders provided in the options to evaluate them one by one.

### Step 3: Analyze Each Disorder
1. **Down Syndrome**: This condition is characterized by an extra chromosome 21 (trisomy 21), resulting in 47 chromosomes. Therefore, it does not fit the criteria of having one chromosome less.

**Hint:** Look for conditions that indicate an increase or decrease in chromosome count.

2. **Alpha Thalassemia**: This is a blood disorder related to hemoglobin and does not affect the chromosome number. The chromosome count remains at 46.

**Hint:** Consider whether the disorder affects blood or other traits without altering chromosome count.

3. **Turner Syndrome**: This condition occurs in females who have only one X chromosome (45 chromosomes total: 44 autosomes + 1 X chromosome). This fits the criteria of having one chromosome less than normal.

**Hint:** Focus on syndromes that specifically mention a deficiency in sex chromosomes.

4. **Klinefelter Syndrome**: This syndrome is characterized by the presence of an extra X chromosome in males (XXY), resulting in 47 chromosomes. Thus, it does not meet the criteria.

**Hint:** Look for conditions that involve additional chromosomes rather than a deficiency.

### Step 4: Conclusion
Based on the analysis, the only genetic disorder that has one chromosome less than the normal count of 46 is Turner Syndrome, which has a total of 45 chromosomes.

**Final Answer:** Turner Syndrome is the genetic disorder where patients have one chromosome less than normal humans.