A 4-year-old boy with short stature has bilateral thumb hypoplasia, radial ray defects, café au lait spots, and generalized hyperpigmentation. CBC shows pancytopenia with macrocytosis and raised fetal hemoglobin. Which investigation will confirm the diagnosis?

• A Serum erythropoietin level
• B Red cell adenosine deaminase activity
• C Bone marrow iron stain with Perls reaction
• D Chromosomal breakage study using diepoxybutane ✓

Explanation

Fanconi anemia is an inherited DNA repair defect presenting with radial ray and thumb anomalies, skin pigmentation changes, short stature, and progressive pancytopenia with macrocytosis and raised HbF. Because spontaneous karyotypes may look normal, confirmation uses induced chromosomal breakage with diepoxybutane or mitomycin C, showing excessive breaks and radial figures. Red cell adenosine deaminase is the marker used to distinguish Diamond-Blackfan anemia, which causes isolated red cell aplasia without skeletal thumb defects.

Reference: Nelson Textbook of Pediatrics, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.