ORIGINAL ARTICLESProtein C and protein S assessment in hospital laboratories: which strategy and what role for DNA sequencing?Labrouche, Sylviea; Reboul, Marie-Pierreb; Guérin, Vivianea,b; Vergnes, Christinea; Freyburger, Genevièvea,bAuthor Information Laboratoire d'Hématologie, aE.A.482 Université de Bordeaux 2 and bHôpital Pellegrin, Bordeaux, France. Correspondence and requests for reprints to Dr G. Freyburger, Laboratoire d'Hématologie, Hôpital Pellegrin, 33076 Bordeaux cedex, France. Tel: +33 5 56 79 55 09; fax: +33 5 56 79 60 79; e-mail: email@example.com Received 12 October 2002 Revised 28 January 2003 Accepted 29 January 2003 Blood Coagulation & Fibrinolysis: September 2003 - Volume 14 - Issue 6 - p 531-538 Buy Abstract This paper presents a critical assessment of protein C (PC) and protein S (PS) functional and immunological approaches with regard to DNA sequencing in a large hospital recruitment for thrombosis exploration in more than 1700 consecutive patients. After examination of clinical status and PC and PS phenotype, a genotypic study was implemented for 17 PC-deficient and 28 PS-deficient patients (activity < 70%). Sixty-five percent of the genotyped PC-deficient patients were found to have heterozygous mutations. Among the < 70% values, decreases in PC activity without gene mutation were always slight (mean value 64 ± 7%) while patients presenting a PC gene mutation had a mean 50 ± 17% activity (P< 0.05). Among the eight PC mutations found, only one has previously been described. A novel mutation in the promoter region (−1522), located in the HNF-1 site and associated with the Y226H heterozygous mutation, was found in a 9-month-old girl with 4% PC activity. Determination of PS functional activity was considerably improved by contemporaneous measurement of calibration and samples in a single step. Only 50% of the genotyped PS-deficient patients demonstrated heterozygous alterations of the gene. The benefit of sequencing to identify putative causal mutations was only 39% in PS-deficient women, while it was 90% in men. Among the nine PS mutations found, six have not yet been published. In the present paper, we explain our methodological choices and diagnostic strategy. © 2003 Lippincott Williams & Wilkins, Inc.