4. Pediatrics MCQs

A pediatric patient with short-limbed dwarfism is diagnosed with achondroplasia. The pathogenesis of this disorder involves a mutation in the FGFR3 gene. What is the precise cellular effect of this mutation at the physis?

Achondroplasia is the most common form of short-limbed dwarfism. At the level of the physis (growth plate), which histological zone exhibits the primary defect responsible for the impaired endochondral ossification?

Achondroplasia is an autosomal dominant disorder caused by a gain-of-function mutation in the FGFR3 gene. This mutation primarily exerts its inhibitory effect on which zone of the physis?

Longitudinal bone growth at the physis is tightly regulated by a feedback loop involving Indian Hedgehog (Ihh) and Parathyroid Hormone-related Peptide (PTHrP). Where is Ihh primarily synthesized in the growth plate?

A pediatric orthopedic surgeon evaluates an infant with rhizomelic shortening of the limbs, frontal bossing, and midface hypoplasia. Which of the following specific genetic mutations is the primary cause of this condition?

A 13-year-old obese male presents with groin pain and an obligate externally rotated gait. Radiographs confirm a slipped capital femoral epiphysis (SCFE). The pathological mechanical failure in this condition primarily occurs through which specific histological zone of the proximal femoral physis?

Slipped capital femoral epiphysis (SCFE) and most Salter-Harris fractures typically propagate through which specific histologic zone of the physis?

A 14-month-old child who is barely pulling to stand presents to the emergency department with a spiral fracture of the midshaft femur. The parents state the child 'tripped over a toy.' What is the most appropriate initial management step?

A 5-day-old infant presents with decreased movement of the left lower extremity following a difficult breech delivery. Radiographs reveal a displaced spiral fracture of the midshaft of the left femur. What is the most appropriate initial management?

A newborn has a swollen, externally rotated, and shortened right lower extremity following a breech delivery. Radiographs show the right femoral shaft displaced superiorly and laterally, but the femoral head ossification center is absent. Ultrasound confirms the femoral head remains within the acetabulum. What is the most likely diagnosis?

A neonate is diagnosed with the most common form of short-limb dwarfism. The underlying genetic defect involves a point mutation in the gene encoding for Fibroblast Growth Factor Receptor 3 (FGFR3). What is the cellular consequence of this specific mutation in the epiphyseal plate?

A 5-year-old boy presents with short stature, frontal bossing, and rhizomelic shortening of the limbs.

This condition is caused by a gain-of-function mutation in FGFR3. Which zone of the physis is primarily affected by this mutation?

A 4-year-old boy presents with a history of multiple recurrent long bone fractures following minimal trauma, blue sclerae, and dentinogenesis imperfecta. This condition is most commonly caused by a genetic mutation affecting the synthesis of which of the following structural proteins?

An infant is evaluated for short-limbed dwarfism, frontal bossing, and midface hypoplasia. Genetic testing reveals a gain-of-function mutation in the FGFR3 gene. Which zone of the physis is primarily affected by this mutation?

A 4-year-old child presents with multiple recurring long bone fractures, dentinogenesis imperfecta, and blue sclerae. Skin biopsy reveals an abnormality in Type I collagen. The pathogenesis of this condition is most commonly related to the genetic substitution of which of the following amino acids in the collagen triple helix?

Osteogenesis imperfecta is characterized by bone fragility, osteopenia, and a high susceptibility to fractures. It is most commonly caused by a mutation affecting which of the following?

A 3-year-old child presents with a history of recurrent fractures from minimal trauma, blue sclerae, and early-onset hearing loss. The genetic defect responsible for this condition primarily affects which of the following processes in collagen synthesis?

A 10-year-old child presents with progressive bowing of the lower extremities and widening of the wrists. Laboratory evaluation reveals hypocalcemia, hypophosphatemia, and markedly elevated alkaline phosphatase. Which zone of the physis is primarily widened and disorganized in this pathological state?