Summary
Macrothrombocytic thrombopathia (la dystrophie thrombocytaire hémorragipare congénitale)
has been diagnosed in two sisters (10 and 12 years old) born of a consanguineous marriage.
A short description of the clinical course in both patients is given. Microscopic
examinations of stained blood smears revealed an abnormal size of platelets, the diameter
of 80 per cent of platelets was greater than 4.3 ì. The platelet count in both children
was normal except the period of haemorrhagic crises. The prolongation of bleeding
time and defective prothrombin consumption were the only abnormalities found by means
of routine coagulation study. Plasma clotting factors were normal. Platelets were
lacking factor 1 and 3 but platelets agglutination, viscous metamorphosis and clot
retraction were normal. Two forms of macrothrombocytic thrombopathia were ascertained
in the patients family (17 members) by means of microscopic and coagulation studies.
The first form (homozygous state) is a platelet anomaly associated with defective
prothrombin consumption and bleeding tendency. The second one (heterozygous state)
consists in platelet anomaly only. The authors suggest that macrothrombocytic thrombopathia
is transmitted as an autosomic and incompletely recessive trait, some abnormalities
being detected in heterozygotes. It was suggested that the microscopic examination
of platelets in stained blood smears offers the possibilty for detection of heterozygotes.
The pathogenesis and the mechanism of hemostatic defect of macrothrombocytic thrombopathia
is briefly discussed.
