Question

Genetic Disorders in human is/are: A. Down's syndrome - Trisomy at chromosome 21 B. Parkinson's disease - Tyrosine hydroxylase C. Diabetes mellitus D. Phenylketonuria - Phenylalanine hydroxylase Choose the correct answer from the options given below:

• A. A only \
• B. C and A only \
• C. A and D only \
• D. B only

Hint:

Down's syndrome is an iconic chromosomal disorder (Trisomy 21), and Phenylketonuria (PKU) is a classic example of an inborn error of metabolism caused by a single-gene defect.

Answer 1

The Correct Option is C

Step 1: Concept Human congenital medical conditions can be caused by chromosomal abnormalities (such as structural errors or variations in chromosome count) or specific single-gene mutations that break key metabolic pathways.

Step 2: Meaning * Chromosomal disorders involve large-scale changes to chromosomes. * Mendelian single-gene errors cause specific, predictable metabolic defects.

Step 3: Analysis * Statement A (Down's syndrome): A classic genetic chromosomal disorder caused by an extra copy of chromosome 21 (Trisomy 21) $\rightarrow$ Correct. * Statement B (Parkinson's disease): Primarily a progressive, multifactorial neurodegenerative disease linked to dopamine depletion, rather than behaving as a simple single-gene trait inherited via tyrosine hydroxylase. * Statement C (Diabetes mellitus): A complex, multifactorial endocrine condition heavily influenced by lifestyle and polygenic traits. * Statement D (Phenylketonuria): A classic genetic metabolic disorder inherited in an autosomal recessive pattern, caused by a mutation in the gene encoding phenylalanine hydroxylase $\rightarrow$ Correct.

Step 4: Conclusion The explicitly accurate classical genetic conditions are A and D, matching option C. Final Answer: (C)