BACKGROUND
Clinical features of Jacobsen syndrome include facial dysmorphism, congenital heart defects, digit anomalies and mild to moderate psychomotor retardation. Thrombocytopenia or pancytopenia is observed in one half of patients.
PATIENTS
Two unrelated children, a 6-month- and a 12-year-old, presented with a moderate thrombocytopenia associated with the clinical features of Jacobsen syndrome. Bone marrow aspirates showed, in both patients, normal cellularity with an increased number of micromegacaryocytes. Chromosome analysis showed a partial deletion of the long arm of chromosome 11. The 12-year-old patient had a history of upper respiratory airways infections with immune humoral deficiency (decreased level of IgA and IgM) which, to our knowledge, has never been reported.
CONCLUSION
Jacobsen syndrome is a cause of inherited thrombocytopenia in children. Humoral immune functions must be explored in patients with a history of repeated infections.