Features of the Upshaw-Schulman Syndrome:
(1) The onset is during the neonatal period or early infancy.
(2) The patient suffers episodes of a microangiopathic hemolytic anemia with thrombocytopenia, hyperbilirubinemia, fever, renal dysfunction and neurologic dysfunction.
(3) The patient experiences frequent relapses.
(4) Plasma shows a deficiency in von Willebrand factor cleaving protease (VWFCP) activity.
(5) The patient responds to infusions of fresh frozen plasma (which provides VWFCP)
Women with USS who become pregnant develop a number of complications such as thrombocytopenia and increased fetal wastage.
The diagnosis requires excluding other causes of TTP.
Because the diagnosis is rare it is frequently misdiagnosed as another disorder. It is important to measure VWFCP activity if unexplained thrombocytopenia occurs during childhood or pregnancy.
