OC 57.2 - Protein S deficiency: impact of molecular investigations on phenotypes profiling

Tuesday, June 25, 2024

09:45 – 10:00 ICT

Room: 210 A-D

Co-Author(s)

GT

Giovanni, L. Tiscia

Senior Researcher
Fondazione Casa Sollievo della Sofferenza
San Giovanni Rotondo, Puglia, Italy
GD

Giovanna D'Andrea

Full Researcher
University of Foggia
Foggia, Puglia, Italy
PD

Patrizia De Bonis

Senior Researcher
Fondazione Casa Sollievo della Sofferenza
San Giovanni Rotondo, Puglia, Italy
FC

Filomena Cappucci

Technician
Fondazione Casa Sollievo della Sofferenza
San Giovanni R, Puglia, Italy
LF

Lucia Fischetti

Technician
Fondazione Casa Sollievo della Sofferenza
San Giovanni Rotondo, Puglia, Italy
MP

Maria Paola Palumbo

Technician
Fondazione Casa Sollievo della Sofferenza
San Giovanni Rotondo, Puglia, Italy
AC

Annamaria Celozzi

Technician
University of Foggia
Foggia, Puglia, Italy
AD

Antonio De Laurenzo

Technician
Fondazione Casa Sollievo della Sofferenza
San Giovanni Rotondo, Puglia, Italy
MG

Michela Gurgoglione

Technician
Fondazione Casa Sollievo della Sofferenza
San Giovanni Rotondo, Puglia, Italy
EC

Elena Chinni

Senior Researcher
Fondazione Casa Sollievo della Sofferenza
San Giovanni Rotondo, Puglia, Italy
DC

Donatella Colaizzo

Senior Researcher
Fondazione Casa Sollievo della Sofferenza
San Giovanni Rotondo, Puglia, Italy

Presenting Author(s)

MM

Maurizio Margaglione, MD

Prof.
University of Foggia
FOGGIA, Puglia, Italy

Co-Author(s)

Elvira Grandone

Head of Unit
Fondazione Casa Sollievo della Sofferenza
San Giovanni Rotondo, Puglia, Italy

Background: Among patients with protein S deficiency it has been shown that the lower the protein level, the greater is the odd of thrombotic events. To date, more than 300 PROS1 genetic variants have been reported.

Aims: To investigate mutations in Protein S-deficient patients with thrombosis to explore genotype/phenotype correlation.

Methods: Free protein S levels were obtained by a turbidimetric method and genetic investigations carried out using Sanger/Next-Generation-Sequencing. Novel mutations were interpreted according to ACMG guidelines. mRNA was isolated to obtain cDNA and used for direct sequencing.

Results: We investigated 15 probands and their relatives with a confirmed protein S deficiency (Table 1). Median age at observation was 46 years (IQR: 32.0;65.0), mostly women (8, 61.5%). They suffered mainly from pulmonary embolism (n= 3, one case observed in the postpartum period). Notably, two members of the same family (a young man and his mother were diagnosed with a splanchnic and cerebral thrombosis, respectively). As for genetics, seven novel variants with a possible deleterious effect (ACMG guidelines) were identified. The in-frame c.346+3A>TA variant, causing a skipping of PROS1 exon 4, had a significant impact on the protein (Figure 1). Among the remaining six variants, one was observed in a splicing site (#1), three were in an already known mutational site (# 6, 11, 12). The variant described in the #12 determines an unstable protein. One further mutation was in the promoter region and one was an in-frame deletion in the exon 12 likely causing a shorter protein (#7). The #13 with juvenile stroke carried the previously described p.Pro626= variant, already demonstrated to influences mRNA maturation.
Mutations impacting on glycosylation (#9), causing deletion (#7) or an unstable protein (#12) are associated with the lowest protein circulating levels.

Conclusion(s): PROS1 investigation can be helpful in predicting protein S plasma levels and possibly clinical phenotype.