4. Pediatrics MCQs

An infant with achondroplasia presents with newly identified central sleep apnea, hyperreflexia, and clonus. What is the most critical next step in management?

A newborn presents with micromelic short stature, bilateral severe rigid clubfeet, "hitchhiker" thumbs, and swollen cauliflower ears. What is the genetic inheritance pattern and defective gene responsible for this condition?

A 5-year-old child presents with a waddling gait, short stature, and joint laxity, but has completely normal facial features. Radiographs show delayed epiphyseal ossification and platyspondyly with anterior tongue-like projections. What is the most likely defective gene?

A 10-year-old child presents with bilateral hip pain and a waddling gait. Radiographs reveal flattened, fragmented capital femoral epiphyses bilaterally, but normal spine morphology. Which of the following best differentiates this condition from bilateral Legg-Calve-Perthes disease?

A young child presents with severe short limb dwarfism, prominent eyes, and a highly arched palate. Laboratory tests reveal asymptomatic hypercalcemia and hypophosphatemia, with low levels of intact PTH. What is the pathogenesis of this condition?

A 12-year-old with achondroplasia is undergoing bilateral lower extremity lengthening. Which of the following anatomic principles or complication risks must the surgeon consider unique to or highly prominent in achondroplastic patients?

A 4-year-old boy with a known diagnosis of achondroplasia presents for evaluation. His parents are concerned about his short limbs. Genetic analysis confirms a gain-of-function mutation in the FGFR3 gene. What is the primary cellular mechanism by which this mutation leads to the characteristic skeletal phenotype?

A newborn presents with severe short-limbed dwarfism, bilateral clubfeet, hitchhiker thumbs, and cystic swelling of the external ears (cauliflower ears). Which of the following genes is most likely mutated in this patient?

A 5-year-old girl is evaluated for short stature and a waddling gait. Clinical examination reveals normal facial features and intelligence. Radiographs demonstrate delayed epiphyseal ossification and irregular, fragmented epiphyses. Genetic testing is most likely to reveal a mutation in which of the following?

A 6-year-old child with Morquio Syndrome (Mucopolysaccharidosis Type IV) presents with genu valgum and a barrel chest. A defect in which of the following enzymes is responsible for this condition?

A 3-year-old child presents with bowed legs, a waddling gait, and short stature. Radiographs show coxa vara and flared, irregular metaphyses. The spine and facial features are completely normal. Genetic testing reveals a mutation in COL10A1. What is the diagnosis?

A newborn is evaluated for skeletal disproportion. Radiographs reveal unusually short, dumbbell-shaped femora, coronal clefts in the vertebral bodies, and platyspondyly. Clinically, the infant has a cleft palate and prominent joints. What is the most likely diagnosis?

A neonate is born with severe anterolateral bowing of the lower extremities, clubfeet, and ambiguous genitalia. Chromosomal analysis reveals a 46,XY karyotype despite female external genitalia. The infant shortly develops severe respiratory distress due to tracheomalacia. This condition is associated with a mutation in which gene?

A 5-year-old child exhibits profound short stature, prominent eyes, and micrognathia. Laboratory tests reveal marked hypercalcemia and hypophosphatemia, with low-normal levels of parathyroid hormone (PTH). Radiographs demonstrate severe metaphyseal irregularity and osteopenia. A mutation in which of the following is most likely?

An 8-year-old child is evaluated for joint pain and a waddling gait. Radiographs demonstrate small, irregular epiphyses with a normal spine. A lateral knee radiograph reveals a pathognomonic 'double-layer' patella. A mutation in which gene is most likely responsible?

A 4-year-old boy presents with short limbs and a waddling gait but normal facial features. Radiographs show delayed epiphyseal ossification, irregular flared metaphyses, and a normal skull. What is the inheritance pattern and associated gene for this condition?

A newborn is diagnosed with Ellis-van Creveld syndrome (Chondroectodermal Dysplasia). In addition to short limbs, polydactyly, and an atrial septal defect, which of the following lower extremity deformities is most likely to develop as the child grows?