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Question #45899
The Question
A female patient suffering from Severe Combined Immunodeficiency (SCID) due to Adenosine Deaminase (ADA) deficiency is treated with somatic gene therapy. A retroviral vector is used to introduce functional ADA cDNA into her extracted lymphocytes, which are then returned to her body. She later marries a male who is heterozygous for the ADA mutation. Which of the following statements is CORRECT regarding her treatment and the genetic risk to her future offspring?
Options
- A.
The therapy provides a permanent cure for the patient, and there is a 25% probability that her offspring will be ADA deficient.
- B.
The patient will require periodic infusions of genetically engineered lymphocytes, and there is a 50% probability that her offspring will be ADA deficient.
- C.
The functional ADA cDNA will eventually integrate into her germinal epithelium, reducing the probability of ADA deficiency in her offspring to 0%.
- D.
The therapy provides a permanent cure, but her offspring have a 50% probability of being ADA deficient due to the inheritance of cryptic splice-site mutations.
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
ADA Deficiency Genetic Correction|Genetic Code Degeneracy|Gene Therapy
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students frequently confuse the clinical success of somatic gene therapy with a true genetic/germline cure.
This question tests the integration of two distinct NCERT concepts: the specific limitation of lymphocyte-based gene therapy (it is not permanent) and the application of Mendelian genetics (a test cross) to a patient whose somatic phenotype has been artificially corrected but whose germline genotype remains defective.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Molecular Basis of Inheritance - Class 12 |
| Concept | Genetic Code Degeneracy |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |