Identificación por nuestro grupo de una nueva mutación en el gen GP1BA (P.W246L) asociada al fenotipo PT-VWD. Sexta mutación reportada internacionalmente / Identification by our group of a novel mutation in the GP1BA gene (P.W246L) responsible for PT-VWD. The 6th mutation internationally reported

La enfermedad de von Willebrand tipo plaquetario (PT-VWD) y tipo 2B (2B-VWD) son trastornos hemorrágicos raros, caracterizados por agregación plaquetaria a bajas concentraciones de ristocetina (RIPA). El diagnóstico diferencial no es fácil y representa un desafío. Hasta el presente, sólo se habían reportado cinco mutaciones en el gen GP1BA relacionadas con este desorden. Describimos aquí la sexta mutación relacionada con PT-VWD, en un paciente con sintomatología hemorrágica severa, macro-trombocitopenia, leve agregación plaquetaria espontánea, RIPA positivo a 0,3 y 0,4 mg/mL, VWF:RCo/VWF: Ag<0,2 y estudios discriminatorios positivos para PT-VWD. VWFpp/VWF: Ag resultó normal a diferencia del 2B-VWD que en algunas oportunidades resulta afectado. El exón 28 del gen VWF del paciente y su madre no reveló mutaciones. Identificamos una sustitución G>T en el nucleótido 3805 en el gen GP1BA del paciente, resultando en un cambio de Trp a Leu en el residuo 246 (p.W246L), en la región de la GPIBa que une al VWF. Esta mutación no se identificó en su madre ni en 100 controles sanos. Es considerada como dañina por análisis in sílico. Consideramos que esta sustitución es responsable del fenotipo PT-VWD del paciente. Dada la ausencia de la misma en los 100 normales estudiados, no se considera un polimorfismo

Platelet-type von Willebrand disease (PT-VWD) and type 2B von Willebrand disease (2B-VWD) are rare bleeding disorders characterized by increased ristocetin-induced platelet aggregation (RIPA) at low concentrations. Diagnosis of either condition is not easy and the differential diagnosis is especially challenging. Five mutations in the GP1BA gene related to PT-VWD and near 50 patients are currently reported worldwide. We herein describe a patient with severe bleeding symptoms, macro thrombocytopenia, mild spontaneous platelet aggregation, positive RIPA at 0.3 and 0.4 mg/mL, VWF: RCo/VWF: Ag <0.2, normal VWFpp/VWF: Ag ratio, and RIPA mixing tests and cryoprecipitate challenge positive for PT-VWD. GP1BA gene was studied in the patient, his mother, and 100 healthy control subjects. We identified a substitution G>T at nucleotide 3805 in the patient's GP1BA gene, resulting in a Trp to Leu amino acid change at residue 246 (p.W246L), within the VWF binding region. This mutation was absent in his unaffected mother and also in the 100 controls, and was predicted as damaging by in silico analysis. The residue is located in a strongly conserved position in the phylogenetic tree. These findings argue in favor of considering this substitution does not represent a polymorphism, and is therefore responsible for the PT-VWD phenotype of the patient

Management of a pregnant patient at term with Von Willebrand disease - III

Von Willebrand disease [VWD] is a common inherited bleeding disorder involving a deficiency or abnormal function of a blood clotting protein called Von Willebrand factor [VWF]. Women with VWD require monitoring during and after pregnancy. This case report describe management of a patient presenting with type III VWD at term and during labour. She had history of severe post-partum haemorrhage [PPH] after cesarean section in previous pregnancy and again had a risk of life-threatening PPH in the current gestation which was managed by appropriate planning and timely decision

Polymorphism in the promoter region of von Willebrand factor gene and von Willebrand disease type 1

The -1185A/G polymorphism in the 5'-regulatory region of the von Willebrand factor (VWF) gene was associated with VWF plasma levels in a normal population. This study was undertaken to evaluate whether there is a relationship between this polymorphism and type 1 von Willebrand disease (VWD), a disorder characterized by a quantitative deficiency of VWF. The association between this polymorphism and plasma VWF levels in normal Brazilian individuals was also analyzed. Control subjects (n = 460) and type 1 VWD patients (n = 41) were studied. Polymerase chain reaction (PCR) amplification of the 864-bp VWF promoter region followed by AccII restriction-digestion was used to identify the -1185A/G genotypes. The -1185G allele frequency was 57 percent in normal individuals and 63 percent in type 1 VWD patients, this difference was not significant (p = 0.29). No significant association was observed between -1185A/G genotypes and VWF plasma levels in normal individuals, although VWF levels were in the same direction as those reported by another study, with subjects carrying the G allele having the lower levels. These results suggest that -1185A/G polymorphism is not associated with the partial deficiency of VWF in type 1 VWD patients.

von Willebrand disease with G4022A mutation (vWd Sungnam): a case report

A 10-year-old male patient affected by type 2 von Willebrand disease (vWD) and his family members were investigated by hemostatic and molecular genetic studies. The propositus, who experienced frequent bleeding episodes, was characterized by a normal level of von Willebrand factor (vWF) antigen (54%), reduced vWF ristocetin cofactor activity (5%), decreased factor VIII clotting activity (25%) and absent high molecular weight multimers in the plasma. An exon 28 fragment coding for the A1 and A2 domains was amplified by polymerase chain reaction and sequenced. We found a heterozygous mutation (G4022A), producing an additional PstI restriction site, which resulted in the substitution of Arg578Gln. Family studies, including the parents and a brother, were negative for this mutation and vWF abnormalities were not observed. We confirmed that G to A mutation in the region of the platelet glycoprotein Ib binding domain of vWF causes the qualitative type 2 defect in von Willebrand disease.

Síndrome de Wildervanck: presentación de un caso / Wildervank's syndrome: a case report

En este trabajo se describe a una paciente con síndrome de Wildervanck, desde el punto de vista genético y clínico; esta enfermedad se caracteriza por la tríada: disminución de la sensibilidad auditiva, secuencia de Klippel-Feil y fenómeno Duane. El árbol genealógico apoya la hipótesis acerca de la herencia poligénica con limitación al sexo femenino de esta entidad