Transcobalamin II Deficiency in Four Cases with Novel Mutations.
OBJECTIVE
Transcobalamin II deficiency is one of the rare causes of inherited vitamin B12 disorders in which the patients have characteristically normal or high vitamin B12 levels related to the transport defect of vitamin B12 into the cell, ending up with intracellular cobalamin depletion and high homocysteine and methylmalonic acid levels.


METHODS
Herein, we describe the findings at presentation of four patients who were diagnosed to have transcobalamin II deficiency with novel mutations.


RESULTS
These patients with transcobalamin II deficiency were found to have novel mutations, of whom 2 had the same large deletion (homozygous c.1106+1516-1222+1231del).


CONCLUSIONS
Transcobalamin II deficiency should be considered in differential diagnosis of any infant with pancytopenia, failure to thrive, diarrhea, and vomiting.
Hacettepe University Faculty of Medicine, Division of Pediatric Hematology, Ankara, Turkey Phone: +90 312 305 11 70 E-mail: suleunal@hacettepe.edu.tr.
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Çetin
D000749:Anemia, Megaloblastic / Q000097:blood / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D001853:Bone Marrow / Q000473:pathology; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics; D018389:Codon, Nonsense; D003241:Consanguinity; D005183:Failure to Thrive / Q000209:etiology; D005260:Female; D005492:Folic Acid / Q000627:therapeutic use; D016368:Frameshift Mutation; D005838:Genotype; D006801:Humans; D006879:Hydroxocobalamin / Q000627:therapeutic use; D007223:Infant; D008297:Male; D009154:Mutation; D020125:Mutation, Missense; D010198:Pancytopenia / Q000097:blood / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D017384:Sequence Deletion; D014155:Transcobalamins / Q000172:deficiency / Q000235:genetics*; D014805:Vitamin B 12 / Q000627:therapeutic use; D014839:Vomiting / Q000209:etiology; D017086:beta-Thalassemia / Q000235:genetics
D018389:Codon, Nonsense; D014155:Transcobalamins; D005492:Folic Acid; D014805:Vitamin B 12; D006879:Hydroxocobalamin