Question
A 29-year-old G3P2 female gives birth to an infant with less than 5th percentile height. The head and torso are of normal size but extremities are short. The forehead is prominent and the infant has bowed legs. There is no osteopenia. The other 2 children are of normal height. What is the most likely diagnosis?
| A. |
Rickets
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| B. |
Osteogenesis imperfecta
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| C. |
Osteopetrosis
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| D. |
Achondroplasia
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Show Answer
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Correct Answer � D
Explanation
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|
- Ans.D. Achondroplasia
- The infant has achondroplasia. Since achondroplasia has autosomal dominant inheritance, other children who inherit the mutant gene may be phenotypically normal (incomplete penetrance).
- Achondroplasia is the most common skeletal dysplasia and a major cause of dwarfism.
- Achondroplasia is due to the mutation in the fibroblast growth factor receptor (FGFR3).
- This leads to abnormal cartilage proliferation at growth plates and affects endochondral bone growth.
- Infants present with short stature, rhizomelic shortening of limbs, frontal bossing, and midface deficiency.
- The condition is not associated with changes in longevity, intelligence, or reproductive status.
