4. Pediatrics MCQs

A 10-year-old child presents with progressive facial distortion, a wide nasal bridge, and bilateral conductive hearing loss. Radiographs show widened metaphyses of the long bones. A mutation in the ANKH gene is identified. What is the primary pathomechanism of this mutation?

An Amish child is diagnosed with cartilage-hair hypoplasia after presenting with short-limb dwarfism and an unusually severe varicella infection. The mutated gene responsible for this condition (RMRP) is unique because it encodes for which of the following?

Which of the following combined lower extremity deformities is the most characteristic clinical hallmark of Schmid metaphyseal chondrodysplasia?

A 4-year-old girl is evaluated for a waddling gait and disproportionate short stature. Unlike patients with achondroplasia, her facial features and head circumference are entirely normal. Radiographs show delayed epiphyseal ossification and irregular, widened metaphyses. Which gene is most likely implicated?

A male infant is noted to have severe short stature and bowing of the femurs. Radiographs at birth show marked metaphyseal irregularity and splaying. By age 3, these radiographic abnormalities spontaneously resolve, though the patient remains short. Which gene is most likely responsible for this self-limiting condition?

A 6-month-old infant with achondroplasia is noted during a routine exam to have brisk deep tendon reflexes, clonus, and reports of central sleep apnea. Which of the following is the most appropriate next step in management?

An 8-year-old child with genetically confirmed Schmid metaphyseal chondrodysplasia has progressive severe coxa vara with a neck-shaft angle of 90 degrees. He is experiencing hip pain and a worsening Trendelenburg gait. What is the most appropriate surgical management?

In achondroplasia, the underlying genetic defect is a point mutation in the FGFR3 gene. This mutation results in a gain-of-function that directly causes which of the following abnormalities at the growth plate?

A 7-year-old boy is evaluated for disproportionate short stature. He lacks the frontal bossing and midface hypoplasia typical of classic achondroplasia. Radiographs show mild narrowing of the lumbar interpedicular distances and squared, shortened long bone diaphyses with slightly flared metaphyses. Which genetic abnormality is most likely present?

A 6-year-old boy presents with short stature, severe genu varum, and a waddling gait. Laboratory studies, including serum calcium, phosphorus, alkaline phosphatase, and vitamin D, are entirely normal. Radiographs reveal widened physes and irregular, flared metaphyses. A mutation in the COL10A1 gene is confirmed. Which physeal zone is primarily affected by this genetic mutation?

A 4-year-old child presents with failure to thrive, steatorrhea, and short stature. Radiographs show symmetrical metaphyseal dysplasia primarily affecting the hips and knees. A complete blood count reveals absolute neutropenia. What is the most likely diagnosis?

A 14-year-old boy is evaluated for mild genu valgum. Radiographs reveal massive widening of the metaphyses of the long bones, classically described as an "Erlenmeyer flask" deformity, with marked cortical thinning. His skull radiographs are entirely normal. What is the most likely diagnosis?

Achondroplasia is caused by a gain-of-function mutation in the FGFR3 gene. This mutation primarily inhibits chondrocyte proliferation and differentiation. Which zone of the physis is directly suppressed in this condition?

A 6-year-old boy presents with a waddling gait and bowing of the lower extremities. Laboratory studies reveal normal calcium, phosphorus, and alkaline phosphatase. Radiographs demonstrate coxa vara and widened, irregular metaphyses, but the epiphyses are completely normal. Genetic testing reveals a mutation in COL10A1. Which specific zone of the physis is primarily disrupted by this pathogenesis?

A 2-year-old child of Amish descent is evaluated for short-limbed dwarfism. Physical examination notes fine, sparse hair and redundant skin. The child has a history of recurrent severe respiratory infections. Radiographs reveal metaphyseal flaring and irregularity. A mutation in which of the following is most likely responsible for this syndrome?

A 4-year-old girl is referred to pediatric orthopedics for short stature and symmetrical metaphyseal irregularities on radiographs. Her medical history is significant for chronic steatorrhea and failure to thrive. Which of the following hematologic abnormalities is most commonly associated with her underlying diagnosis?

A 15-year-old asymptomatic female is evaluated for mild genu valgum. Radiographs exhibit striking, symmetrical widening of the distal femoral and proximal tibial metaphyses, classically described as an "Erlenmeyer flask" deformity, with significant cortical thinning. Her calvarium and cranial nerves are clinically and radiographically normal. What is the most likely diagnosis?

An infant is born with a remarkably long, narrow trunk and severely shortened limbs. A prominent tail-like appendage is noted over the sacrum. Radiographs demonstrate marked platyspondyly and severe metaphyseal flaring, giving the long bones a dumbbell shape. As this child matures, what is the most critical and progressive orthopedic complication that requires close monitoring?

An 8-year-old boy with a known history of Schmid type metaphyseal chondrodysplasia presents with worsening waddling gait and bilateral hip pain. Radiographs confirm severe, progressive coxa vara with a neck-shaft angle of 85 degrees and a vertical physeal angle. What is the most appropriate definitive management?