Protein C and protein S assessment in hospital laboratories

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.

Co‐segregation of the PROS1 locus and protein S deficiency in families having no detectable mutations in PROS1

“…Thus, the preferred way to screen for mutations is by direct sequencing of the PROS1 coding sequences, although it is more expensive than other screening techniques. The direct sequencing approach has been used in the majority of studies, including 147 families with PS deficiency [10,17,23,25,26,29,32,33]. Despite using this approach, 46% of the cases did not reveal any PROS1 mutations.…”

“…Nevertheless, screening for PROS1 gene mutations has been performed in a number of studies. The proportion of cases where no mutations are detected varies widely between studies [10,17,[23][24][25][26][27][28][29][30][31][32][33]. When all cases are pooled together, PROS1 gene mutations are not detected in 47% of PS deficient families.…”

A novel rare c. -39C>T mutation in thePROS15’UTR causing PS deficiency by creating a new upstream translation initiation codon and inhibiting the production of the natural protein

“…Standard thrombophilia screening revealed a Type I PSD (Fig 1; Supp Table 1). However, no candidate deleterious PROS1 mutation nor large genomic rearrangement were detected by Sanger sequencing of the 15 PROS1 exons and of their flanking intronic regions (Labrouche et al , 2003) or by multiplex ligation dependent probe amplification (MLPA) using Salsa MLPA kit (P112; MRC-Holland, Amsterdam, the Netherlands), respectively. As the proband reported at least one first degree relative with VT, family members were invited to participate to a genetic exploration upon informed consent agreement according to the Helsinki declaration.…”

A novel mutation Gly222Arg in PROS1 causing protein S deficiency in a patient with pulmonary embolism

“…Protein S deficiency (PSD) could be described in three types. All three types of PSD have the manifestation of decreased PS function; therefore, a continuously significant decrease in PS activity could be regarded as a reminder of PSD . Herein, we report a novel mutation Gly222Arg in chromosome 3q11( PROS1 ) which leads to protein S deficiency in a patient with multiple venous thrombosis and pulmonary embolism.…”