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Question #45832
The Question
A severe genetic disorder is caused by a mutation in an X-linked gene coding for a structural muscle protein. Patients exhibit both progressive skeletal muscle degeneration and severe early-onset cardiomyopathy. Which of the following statements regarding the genetics of this disorder is INCORRECT?
Options
- A.
The mutated gene exhibits pleiotropy, as a single gene mutation produces multiple distinct phenotypic expressions in different tissues.
- B.
Assuming no new mutations, the frequency of this allele will remain stable in Hardy-Weinberg equilibrium because heterozygous females are phenotypically normal.
- C.
In a pedigree analysis, the disorder will demonstrate criss-cross inheritance, and an affected male will never transmit the defective allele to his sons.
- D.
Heterozygous females act as the primary reservoir for this allele in the population, as the cardiomyopathy drastically reduces the reproductive fitness of affected males.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Color Blindness|Duchenne Muscular Dystrophy|Pleiotropy
Why This Question Is Tricky
Common Mistakes
The 'Conceptual Pivot' is the synthesis of Mendelian inheritance with Population Genetics.
A common misconception is that recessive alleles are perfectly protected from natural selection by heterozygous carriers, thus maintaining Hardy-Weinberg equilibrium.
However, for X-linked traits, the allele is fully exposed to selection in hemizygous males.
If the pleiotropic effects (like heart failure) reduce reproductive fitness to near zero, natural selection is actively occurring, which disrupts Hardy-Weinberg equilibrium.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Principles of Inheritance and Variation - Class 12 |
| Concept | Sex-Linked Recessive Inheritance |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |