Megaloblastic anemia due to hereditary intrinsic factor deficiency presenting as recurrent anemia in a young girl—a case report

Background: Childhood anemia is a very common problem in India, out of which more than one-third is attributed to vitamin B12 deficiency. Aim: To follow up on a girl with recurrent anemia who was later diagnosed with hereditary intrinsic factor deficiency. Methods: An eight-year-old girl presented with recurrent anemia, easy fatigability, poor appetite, and abdominal pain for one month. The hemoglobin was 4.3 g/dL, and the peripheral smear showed a dimorphic picture. Serum vitamin B12 was severely low at <50 pg/mL. After a packed red blood cell transfusion, she was advised to take oral vitamin B12 and iron supplements. Her symptoms and vitamin B12 levels did not improve on follow-up, which led to suspicion of a congenital intrinsic factor deficiency (proven by whole exome sequencing). The child is currently doing well on monthly vitamin B12 injections. Summary: This case highlights the importance of considering rare inherited causes in a child with recurrent severe anemia, even in regions where nutritional deficiencies are common.