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4. Pediatrics MCQs

Practice Set 285 of 334

This practice set contains high-yield board review questions covering key concepts in 4. Pediatrics. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 5681

Topic: 4. Pediatrics

A 12-year-old boy with achondroplasia is compared to his unaffected peer. Based on the clinical appearance shown below, which of the following statements regarding his trunk and chest is accurate?


. The trunk is significantly shorter than that of an unaffected peer.
. The chest and shoulders are narrower compared to an unaffected peer.
. The chest is barrel-shaped and wider than normal.
. The shoulders are disproportionately broad.
. There is a severe structural scoliosis present.

Correct Answer & Explanation

. The chest and shoulders are narrower compared to an unaffected peer.

Explanation

Correct Answer: The chest and shoulders are narrower compared to an unaffected peer.In achondroplasia, there is no significant difference in the height of the trunk compared to unaffected individuals; however, the chest and shoulders are characteristically narrower.

Question 5682

Topic: 4. Pediatrics

A family asks about the expected adult height for their male child recently diagnosed with achondroplasia. According to standard growth data for this condition, what is the mean adult height for males?

. 110 +/- 5 cm
. 124 +/- 5.9 cm
. 131 +/- 5.6 cm
. 145 +/- 6 cm
. 155 +/- 5 cm

Correct Answer & Explanation

. 131 +/- 5.6 cm

Explanation

Correct Answer: 131 +/- 5.6 cmThe mean adult height in males with achondroplasia is 131 +/- 5.6 cm, whereas in females it is 124 +/- 5.9 cm.

Question 5683

Topic: 4. Pediatrics

A 25-year-old male with achondroplasia is planning to start a family with a female of normal stature. What is the inheritance pattern of his condition, and what is the risk of passing the mutation to his offspring?

. Autosomal recessive; 0% risk if the mother is not a carrier
. Autosomal dominant; 50% risk
. X-linked dominant; 100% risk for female offspring
. X-linked recessive; 0% risk for male offspring
. Mitochondrial; 0% risk

Correct Answer & Explanation

. Autosomal dominant; 50% risk

Explanation

Correct Answer: Autosomal dominant; 50% riskAchondroplasia is inherited in an autosomal dominant manner. An affected individual has a 50% chance of passing the mutated gene to each offspring, regardless of the child's sex.

Question 5684

Topic: 4. Pediatrics

A couple with normal stature has a child diagnosed with achondroplasia. They are concerned about the risk of having another child with the same condition. What is the most likely genetic mechanism responsible for their child's condition?

. Autosomal recessive inheritance from carrier parents
. X-linked recessive mutation
. De novo mutation on the distal short arm of chromosome 4
. Maternal nondisjunction of chromosome 21

Correct Answer & Explanation

. De novo mutation on the distal short arm of chromosome 4

Explanation

Correct Answer: De novo mutation on the distal short arm of chromosome 4Achondroplasia is inherited in an autosomal dominant manner. However, over 80% of individuals with achondroplasia have parents with normal stature, meaning the condition is the result of a 'de novo' (new) mutation. This gene is localized to the distal short arm of chromosome 4 (FGFR3 gene).

Question 5685

Topic: 4. Pediatrics

An infant is diagnosed with the most common form of human chondrodysplasia. While life span is generally normal, there is an increased risk of death in infancy. Which of the following is the primary cause of this increased mortality risk?

. Severe restrictive lung disease from a bell-shaped thorax
. Congenital cardiac septal defects
. Compression of the spinal cord and upper airway obstruction
. Recurrent severe pulmonary infections due to immunodeficiency

Correct Answer & Explanation

. Compression of the spinal cord and upper airway obstruction

Explanation

Correct Answer: Compression of the spinal cord and upper airway obstructionIn achondroplasia, intelligence and life span are usually normal. However, compression of the spinal cord (often at the foramen magnum) and upper airway obstruction significantly increase the risk of death during infancy.

Question 5686

Topic: 4. Pediatrics

A 3-year-old boy is evaluated for delayed motor milestones. His clinical appearance is shown below. Which of the following best describes the craniofacial characteristics associated with this syndrome?


. Microcephaly with a prominent occiput
. Disproportionately large head, prominent forehead, and depressed nasal bridge
. Craniosynostosis with midface hypoplasia and proptosis
. Normal head circumference with a highly arched palate

Correct Answer & Explanation

. Disproportionately large head, prominent forehead, and depressed nasal bridge

Explanation

Correct Answer: Disproportionately large head, prominent forehead, and depressed nasal bridgeThe image shows the classic facial features of achondroplasia. The head is disproportionately large in relation to height (macrocephaly), the forehead is prominent (frontal bossing), and the nasal bridge is broadened and depressed.

Question 5687

Topic: 4. Pediatrics

A pediatrician refers a 9-month-old infant with achondroplasia to the orthopedic clinic due to concerns about delayed motor milestones. The parents are highly anxious about the child's future cognitive development. What is the most appropriate counseling to provide regarding this child's developmental trajectory?

. Motor delays are typical due to hypotonia, but intelligence is usually normal.
. Motor delays are secondary to severe intellectual disability.
. Motor milestones are typically achieved on time, so alternative diagnoses should be considered.
. Both motor and cognitive development will be severely impaired requiring lifelong institutional care.

Correct Answer & Explanation

. Motor delays are typical due to hypotonia, but intelligence is usually normal.

Explanation

Correct Answer: Motor delays are typical due to hypotonia, but intelligence is usually normal.In infancy, hypotonia is typical in achondroplasia, and the acquisition of developmental motor milestones is often delayed as a result. However, intelligence and overall life span are usually normal.

Question 5688

Topic: 4. Pediatrics

A 10-year-old female with achondroplasia and her parents are inquiring about her expected final adult height. Based on epidemiological data for this condition, what is the mean adult height for females?

. 105 cm
. 124 cm
. 131 cm
. 145 cm

Correct Answer & Explanation

. 124 cm

Explanation

Correct Answer: 124 cmIn achondroplasia, the mean adult height in males is 131 +/- 5.6 cm, and in females, it is 124 +/- 5.9 cm.

Question 5689

Topic: 4. Pediatrics

A clinical comparison between a patient with achondroplasia and an age-matched individual of normal stature is shown below. Which of the following statements accurately describes the axial skeletal proportions in the affected individual?


. The trunk height is significantly shorter than the normal individual.
. There is no difference in trunk height, but the chest and shoulders are narrower.
. The trunk height is longer, compensating for the short limbs.
. The chest and shoulders are significantly broader than the normal individual.

Correct Answer & Explanation

. There is no difference in trunk height, but the chest and shoulders are narrower.

Explanation

Correct Answer: There is no difference in trunk height, but the chest and shoulders are narrower.Achondroplasia is a disproportionate short-limb dwarfism. As demonstrated in the clinical comparison, there is no significant difference in the height of the trunk between an achondroplastic patient and a normal individual; however, the chest and shoulders are notably narrower in achondroplasia.

Question 5690

Topic: 4. Pediatrics

A 3-year-old child presents with the facial features shown in the clinical photograph below. Which of the following genetic mechanisms is most likely responsible for this patient's condition?


. Autosomal recessive inheritance of a COL1A1 mutation.
. X-linked recessive mutation of the PHEX gene.
. De novo mutation of a gene on the distal short arm of chromosome 4.
. Autosomal dominant mutation of the COMP gene.

Correct Answer & Explanation

. De novo mutation of a gene on the distal short arm of chromosome 4.

Explanation

Correct Answer: De novo mutation of a gene on the distal short arm of chromosome 4.The clinical image shows a child with a disproportionately large head, prominent forehead (frontal bossing), and a broadened, depressed nasal bridge, which are classic facial features of achondroplasia. Achondroplasia is caused by a mutation in the FGFR3 gene, localized to the distal short arm of chromosome 4. Over 80% of cases are the result of a de novo (new) mutation in individuals with parents of normal stature.

Question 5691

Topic: 4. Pediatrics

In infants diagnosed with the most common human chondrodysplasia, which of the following complications poses the greatest risk of mortality during the first year of life?

. Atlantoaxial instability leading to cord transection.
. Severe restrictive lung disease due to a bell-shaped thorax.
. Congenital cardiac anomalies such as ventricular septal defect.
. Cervicomedullary compression and upper airway obstruction.

Correct Answer & Explanation

. Cervicomedullary compression and upper airway obstruction.

Explanation

Correct Answer: Cervicomedullary compression and upper airway obstruction.Achondroplasia is the most common chondrodysplasia. In infancy, compression of the spinal cord (specifically cervicomedullary compression at the narrowed foramen magnum) and upper airway obstruction significantly increase the risk of sudden death. Atlantoaxial instability is more characteristic of Down syndrome or Morquio syndrome, while a bell-shaped thorax causing severe restrictive lung disease is classic for asphyxiating thoracic dystrophy (Jeune syndrome) or thanatophoric dysplasia.

Question 5692

Topic: 4. Pediatrics

A 7-year-old patient presents with the clinical posture and lower extremity alignment shown below. Upon physical examination of the upper extremities, which of the following findings is most commonly associated with this syndrome?


. Cubitus valgus with hypermobility of the elbow.
. Madelung deformity of the wrist.
. Limitation of elbow extension and rotation.
. Proximal radioulnar synostosis.

Correct Answer & Explanation

. Limitation of elbow extension and rotation.

Explanation

Correct Answer: Limitation of elbow extension and rotation.The image demonstrates exaggerated lumbar lordosis, genu varum, and hyperextension of the knees, typical of achondroplasia. While many joints in achondroplasia exhibit hyperextensibility (like the knees), the elbow is a notable exception. Limitation of elbow extension and rotation is a very common and classic clinical finding in patients with achondroplasia.

Question 5693

Topic: 4. Pediatrics

A couple with normal stature brings their newborn child to the orthopedic clinic. The child has been diagnosed with achondroplasia. The parents are concerned about the risk of having another child with the same condition. What is the most accurate counseling regarding the etiology of their child's condition?

. It is an autosomal recessive trait, so there is a 25% chance for future pregnancies.
. It is an X-linked dominant trait, affecting only male offspring.
. It is the result of a de novo mutation in over 80% of cases, making the recurrence risk for this couple very low.
. It is caused by a maternal chromosomal nondisjunction event.

Correct Answer & Explanation

. It is the result of a de novo mutation in over 80% of cases, making the recurrence risk for this couple very low.

Explanation

Correct Answer: It is the result of a de novo mutation in over 80% of cases, making the recurrence risk for this couple very low.Achondroplasia is inherited in an autosomal dominant manner. However, over 80% of individuals with achondroplasia have parents with normal stature. In these cases, the condition is the result of a spontaneous 'de novo' mutation. Therefore, the recurrence risk for parents of normal stature who have one affected child is extremely low (though slightly higher than the general population due to the rare possibility of germline mosaicism).

Question 5694

Topic: 4. Pediatrics

A 12-month-old infant with achondroplasia is brought to the clinic by his parents, who are concerned that he is not yet walking or pulling to stand. Which of the following is the most appropriate response regarding his development?

. This indicates severe intellectual disability, which is common in this condition.
. This suggests an impending spinal cord compression and requires immediate surgical decompression.
. This is likely due to typical infantile hypotonia, and motor milestones are often delayed, though intelligence is usually normal.
. This is a sign of progressive muscular dystrophy associated with the syndrome.

Correct Answer & Explanation

. This is likely due to typical infantile hypotonia, and motor milestones are often delayed, though intelligence is usually normal.

Explanation

Correct Answer: This is likely due to typical infantile hypotonia, and motor milestones are often delayed, though intelligence is usually normal.In infancy, patients with achondroplasia typically present with hypotonia. As a result, the acquisition of developmental motor milestones (such as sitting, standing, and walking) is often delayed. However, their intelligence and life span are usually normal. While spinal cord compression is a risk, delayed motor milestones alone in a 12-month-old are expected due to hypotonia and altered biomechanics, not necessarily an acute cord compression.

Question 5695

Topic: 4. Pediatrics

The clinical photograph compares a patient with achondroplasia (left) to an age-matched child with normal stature (right). Based on the typical anthropometric features of this condition, which of the following statements is correct regarding the patient's torso?


. The trunk height is similar to the normal child, but the chest and shoulders are narrower.
. The trunk height is significantly shorter than the normal child.
. The chest is characteristically barrel-shaped and wider than normal.
. The shoulders are broader due to compensatory muscle hypertrophy.

Correct Answer & Explanation

. The trunk height is similar to the normal child, but the chest and shoulders are narrower.

Explanation

Correct Answer: The trunk height is similar to the normal child, but the chest and shoulders are narrower.Achondroplasia is a disproportionate short-limb dwarfism. The shortening primarily affects the appendicular skeleton (rhizomelic shortening). As demonstrated in the clinical image, there is no significant difference in the height of the trunk between an achondroplastic patient and a normal-statured peer; however, the chest and shoulders are characteristically narrower in achondroplasia.

Question 5696

Topic: 4. Pediatrics

An 18-year-old male with achondroplasia presents for a final growth evaluation. According to standard growth curves for this specific skeletal dysplasia, what is the expected mean adult height for males?

. 106 cm
. 124 cm
. 131 cm
. 145 cm

Correct Answer & Explanation

. 131 cm

Explanation

Correct Answer: 131 cmIn achondroplasia, the mean adult height for males is approximately 131 +/- 5.6 cm. For females, the mean adult height is slightly lower, at approximately 124 +/- 5.9 cm.

Question 5697

Topic: 4. Pediatrics

A couple with normal stature has a child diagnosed with achondroplasia. They are concerned about the risk in future pregnancies and ask how this occurred. What is the most accurate statement regarding the genetics of this condition in their child?

. It is inherited in an autosomal recessive manner
. It is an X-linked dominant trait
. It represents a de novo mutation in over 80% of such cases
. It is caused by a maternal chromosomal nondisjunction

Correct Answer & Explanation

. It represents a de novo mutation in over 80% of such cases

Explanation

Correct Answer: It represents a de novo mutation in over 80% of such casesAchondroplasia is inherited in an autosomal dominant manner. However, over 80% of individuals with achondroplasia have parents with normal stature, meaning the condition is the result of a 'de novo' (new) mutation.

Question 5698

Topic: 4. Pediatrics

A 3-year-old child presents to the orthopedic clinic. Based on the clinical photograph below, which of the following craniofacial features is characteristic of this patient's underlying skeletal dysplasia?


. Microcephaly with a prominent nasal bridge
. Disproportionately large head with a prominent forehead and depressed nasal bridge
. Craniosynostosis with midface hypoplasia
. Normal head size with a high-arched palate

Correct Answer & Explanation

. Disproportionately large head with a prominent forehead and depressed nasal bridge

Explanation

Correct Answer: Disproportionately large head with a prominent forehead and depressed nasal bridgeAs seen in the provided clinical image and described in the text, patients with achondroplasia typically have a head that is disproportionately large in relation to their height, a prominent forehead (frontal bossing), and a broadened, depressed nasal bridge.

Question 5699

Topic: 4. Pediatrics

A 12-year-old boy with achondroplasia presents for a routine follow-up. The clinical photograph below demonstrates his typical standing posture. Which combination of physical findings is most consistent with this condition?


. Exaggerated lumbar lordosis, limitation of elbow extension, and genu varum
. Lumbar kyphosis, hyperlaxity of the elbows, and genu valgum
. Thoracic scoliosis, limitation of knee flexion, and coxa vara
. Loss of lumbar lordosis, elbow ankylosis, and tibial bowing

Correct Answer & Explanation

. Exaggerated lumbar lordosis, limitation of elbow extension, and genu varum

Explanation

Correct Answer: Exaggerated lumbar lordosis, limitation of elbow extension, and genu varumThe clinical image and text highlight that exaggerated lumbar lordosis, limitation of elbow extension and rotation, genu varum, and hyperextension of the knees and most other joints are common findings in achondroplasia.

Question 5700

Topic: 4. Pediatrics

Achondroplasia is the most common of the human chondrodysplasias. The genetic mutation responsible for this condition is localized to which of the following chromosomal regions?

. Long arm of chromosome 15
. Distal short arm of chromosome 4
. Short arm of chromosome X
. Long arm of chromosome 17

Correct Answer & Explanation

. Distal short arm of chromosome 4

Explanation

Correct Answer: Distal short arm of chromosome 4Achondroplasia is caused by a mutation in the FGFR3 gene, which is localized to the distal short arm of chromosome 4.

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