C1272F: a novel tipe 2A von Willebrand disease mutation in A1 domain

WOODS AI; SÁNCHEZ LUCEROS A; KEMPFER AC; POWAZNIAK Y; CALDERAZZO JC; BLANCO AN; LAZZARI MA

Buenos Aires

Congreso; XXIX International Congress of the World Federation of Hemophilia; 2010

World Federation of Hemophilia

Introduction: Type 2A VWD is one of the most common qualitative variants, characterized by the absence of large and intermediate VWF multimers. Most of the mutations are located in the A2 domain (56.7%), whereas 23.9% are located in D’ and CK domains, and 19.4%, in the A1 domain. Objectives: To describe a novel missense mutation in A1 domain, the C1272F, responsible for the 2A phenotype. Material and Methods: The patient had major hemorrhages, sometimes treated with DDAVP or Hemate-P. His bleeding score was 10. His mother suffered major hemorrhage after delivery, menorrhagia, and hematomas. His father and sister had no personal history of bleeding. Exon 28 of the VWF gene was amplified in fragments, and subsequently sequenced. We designed the primers, avoiding pseudogene amplification. Restriction enzyme PST1 was used to digest the fragment 1–2. Results: Laboratory data showed: patient/mother: FVIII:C = 30/35 IU/dL; VWF:Ag = 28/44 IU/dL; VWF:RCo<10/<10 IU/dL; VWF:RCo/VWF:Ag <0.35/0.35, both with absence of high and intermediate molecular weight multimers. Restriction enzyme study with PST1 reported: wild allele (normal): fragments of 22, 125, and 144 bp. Mutant allele: fragments of 22 and 269 bp. Patient’s pattern: fragments of 22, 125, 144, and 269 bp, as the result of an heterozygous substitution. The sequencing analysis (patient and mother) showed heterozygous 3815G fi T transversion within the A1 domain, resulting in the C1272F mutation, which was not found in 100 normal alleles. Conclusion: These facts strongly suggest that C1272F represents a new mutation, responsible for the 2A phenotype. However, expression studies of this mutation will be necessary to confirm its role.