Genetic Disorders · NEET PG Preparation Paediatrics
A 4-year-old boy is evaluated for progressive muscle weakness, frequent falls, and difficulty rising from the floor, for which he uses his hands to w…
Practice question from Genetic Disorders (NEET PG Preparation Paediatrics), with the correct answer and a step-by-step solution.
easy · MCQ · Q-94A3F3
A 4-year-old boy is evaluated for progressive muscle weakness, frequent falls, and difficulty rising from the floor, for which he uses his hands to walk up his thighs (Gowers sign). Examination shows calf pseudohypertrophy. Serum creatine kinase (CK) levels are extremely elevated. Genetic testing reveals a deletion in the dystrophin gene. What is the classic mode of inheritance for this condition?
- A.Autosomal dominant
- B.Autosomal recessive
- C.X-linked recessiveCorrect answer
- D.Mitochondrial inheritance
Solution
Duchenne muscular dystrophy (DMD) is an X-linked recessive disorder caused by mutations in the dystrophin gene on the X chromosome (Xp21). It classically affects males, presenting in early childhood with proximal muscle weakness, calf pseudohypertrophy, Gowers sign, and markedly elevated CK. Females are typically asymptomatic carriers, though rare manifestations can occur due to skewed X-inactivation.
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