Important causes of wheezing in infancy include all of the following except:

Correct Answer: D

Rationale: Hypocalcemia is not a common cause of wheezing in infancy. Bronchiolitis, asthma, and gastroesophageal reflux are frequent causes due to airway inflammation, hyperreactivity, and aspiration of gastric contents.

Correct Answer: A

Rationale: History alone is not always reliable. Many cases of F.B. aspiration present with subtle or delayed symptoms, requiring imaging and bronchoscopy for confirmation.

Correct Answer: A

Rationale: Aplastic anemia is a type of normocytic normochromic anemia characterized by reduced production of all blood cells due to bone marrow failure. Thalassemia and iron deficiency anemia are microcytic hypochromic.

Correct Answer: B

Rationale: A single umbilical artery is associated with an increased risk of occult renal anomalies, as it may indicate underlying developmental abnormalities in the urinary system.

Correct Answer: B

Rationale: Gardner syndrome does not typically increase radiation sensitivity, whereas the other conditions involve DNA repair defects or chromosomal instability.