[Utility of desmopressin in 4 cases of thrombocytopathies associated with giant platelets]. / Utilidad de la desmopresina en cuatro casos de trombocitopatías asociadas a plaquetas gigantes.

Shear-induced aggregation requires the platelet glycoprotein complexes (Gp), the von Willebrand factor (vWf) and ADP. The Bernard Soulier syndrome (BS) and the gray platelet syndrome (GPS) are platelet function defects characterized by absence of GP Ib/IX and alpha granules, respectively, with mucocutaneous hemorrhages, prolonged bleeding time (BT) and moderate thrombocytopenia in both syndromes. There are reports that desmopressin (DDAVP) shortens the BT in some patients with platelet dysfunction. The purpose of this study was to evaluate the response t(DDAVP) in four female patients (2 with GPS plus Marfan's disease and 2 BS). All had bleeding episodes, BTs > 10 minutes, platelet counts (PC) between 40-88 x 10(9)/L and defects in platelet aggregation. The DDAVP was administered at a dose of 0.3 microgram/kg in 15 to 30 mL of isotonic saline given by slow intravenous drip in 30 to 45 min. All patients were studied before and after DDAVP administration (BT, PC, platelet factor, mean platelet volume, factors F.VIII:C, FvW:Ag, FvW:RiC of, and platelet aggregation). After DDAVP infusion the patients had a BT < 6 min, and increased levels of F. VIII:C, FvW:Ag and FvW:RiC of (> 100 Ul/dL), and the bleeding disappeared. We conclude that there was a good response to DDAVP probably associated with improved platelet adhesion, and increases in the multimers of the von Willebrand factor.

[Gray-platelet syndrome associated with Marfan disease in a Mexican family]. / Síndrome de la plaqueta gris asociado a enfermedad de Marfán en una familia mexicana.

Grey-platelet syndrome is a rare familial platelet impairment characterised by lack of alpha granules and giant vacuolated platelets. A Mexican family with grey-platelet syndrome associated to Marfan disease is presented. The family was comprised of 22 members, of whom 3 (the propositus and two of his nephews) could be studied. Two of them, with haemorrhagic symptoms since childhood, had moderate prolongation of the Ivy bleeding time which improved after DDAVP administration, plus moderate thrombocytopenia, giant platelets and abnormal platelet aggregation induced by adrenalin, ADP and collagen. Platelet factor 4 was normal. Electron microscope examination of platelets showed lack of alpha granules and increased dense bodies. The rarity of the casual association of two low-frequency genetic diseases, namely Marfan disease and the grey-platelet syndrome, is commented, along with the response attained with DDAVP in the two affected individuals.