A new inherited thrombocytopenia the Paris-Trousseau syndrome associated with dysmegakaryopoiesis, giant platelet alpha granules, congenital abnormalities and mental retardation due to chromosome 11 deletion at Ilq23 was recently reported (BLOOD 85:1805, 1995). The condition was considered unique, but the authors noted that 47% of patients with a similar deletion of chromosome 11 at 1 Iq23, the Jacobsen syndrome also have thrombocytopenia. We evaluated two patients with Jacobsen syndrome who were thrombocytopenic and observed giant alpha granules in 15% of their platelets (BLOOD 94:81b, 1999). As a result we suggested that the Paris-Trousseau syndrome and the Jacobsen syndrome were probably identical disorders. Now we have evaluated platelets of two patients with Jacobsen syndrome by the whole mount technique for the presence of dense bodies, the organelles storing adenine nucleotides, serotonin and calcium and destined for release when platelets are activated. Dense bodies are absent in platelets from one patient and present at a frequency of 3/100 platelets in the second (controls: 4-8 /platelet). The virtual absence of dense bodies in platelets of patients with the Jacobsen syndrome may be more responsible for mild bleeding symptoms than the modest thrombocytopenia, and may distinguish Jacobsen platelets from Paris-Trousseau platelets that may contain dense bodies.
|Original language||English (US)|
|Issue number||11 PART II|
|State||Published - Dec 1 2000|