Mouse Pros1 (Vitamin K-dependent protein S) ELISA Kit

A 5-year-old girl presented with abdominal pain and bloody stools 2 weeks after suffering from influenza A infection. Enhanced computed tomographic scan showed widespread splanchnic venous thrombosis and small intestine necrosis. She recovered after the necrotic bowel was resected. The patient continues to receive anticoagulant therapy. Thrombophilia screening after the complete resolution consistently showed mildly decreased protein S (PS) activity with normal PS antigen levels. Sequence analysis detected a heterozygous K196E mutation in the PROS1 gene. Type 2 PS deficiency was diagnosed. This is the first report of mesenteric vein thrombosis in a child with a type 2 PS deficiency.

The diagnosis of thrombophilia caused by protein S deficiency remains difficult. From 2005 to 2010, we documented 135 patients with suspected hereditary protein S deficiency for whom mutational analysis of the PROS 1 gene had been performed by direct double-stranded sequencing of the amplified 15 exons including splice sites. Multiplex ligation-dependent probe amplification was performed on 12 of 15 exons in cases with no mutation found but a large deletion in the PROS 1 gene was suspected. Mutations were identified in 49 patients, 9 by familial screening. Altogether, 17 new and 11 previously described mutations of PROS 1 were identified among the 49 patients. After the exclusion of acquired protein S deficiency due to pregnancy or hormonal contraceptives, there remained only 1 case with protein S activity levels less than 40% that could not be explained by sequence variations or deletions in the examined regions of the PROS1 gene. After the exclusion of conditions associated with acquired protein S deficiency, persistently low protein S activity levels are highly indicative of a genetic alteration in PROS1. We observed a clear correlation between the laboratory phenotype and the type of mutation.