title: Pancytopenia with chromosomal fragility: vitamin B12 deficiency.
abstract: OBJECTIVE
  Pancytopenia in children may have many etiologies. Chromosomal abnormalities with pancytopenia is of particular concern because clonal abnormalities indicate a neoplastic process. We describe three children who had vitamin B12 deficiency and who displayed pancytopenia with multiple chromosomal breaks, rearrangements, and deletions consistent with chromosomal fragility. Severe vitamin B12 deficiency is rare in children and should be considered in the differential diagnosis of a child with pancytopenia, dyserythropoiesis, and multiple chromosomal abnormalities.
  
  
  METHODS
  Three children displayed pancytopenia with dyserythropoiesis in the bone marrow. Routine cytogenetic analyses in all three patients were performed and chromosome breakage study was performed on the peripheral blood of one patient after vitamin B12 supplementation.
  
  
  RESULTS
  All three patients had severe vitamin B12 deficiency. Spontaneous chromosomal fragility was seen in routine cytogenetic analyses in all three patients. Vitamin B12 supplementation resolved the pancytopenia in all three patients and spontaneous and diepoxybutane-induced breakage rates in chromosomes were well within normal rates after therapy in one patient.
  
  
  CONCLUSIONS
  The presence of pancytopenia with cytogenetic abnormalities in a child is worrisome. However, careful interpretation of dyserythropoiesis and megaloblastic changes in bone marrow in the aforementioned clinical situation would result in the correct diagnosis of a disorder that is easily cured.
authors.affiliation: Department of Pediatrics, Texas Children's Cancer Center and Hematology Service, Baylor College of Medicine, Texas 77030, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Chintagumpala
authors.forename: Z A
authors.initials: ZA
authors.lastname: Dreyer
authors.forename: C P
authors.initials: CP
authors.lastname: Steuber
authors.forename: L D
authors.initials: LD
authors.lastname: Cooley
mesh_terms: D001853:Bone Marrow / Q000648:ultrastructure; D002675:Child, Preschool; D002873:Chromosome Fragility; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D010198:Pancytopenia / Q000150:complications / Q000235:genetics*; D014806:Vitamin B 12 Deficiency / Q000150:complications / Q000235:genetics*