Molecular study of sticky platelet syndrome using exome sequencing

Abstract

Introduction: Sticky platelet syndrome (SPS) is a prothrombotic condition characterized by increased platelet aggregation that causes arterial and venous thrombosis. Its diagnosis is reached by identifying increased aggregation using low concentrations of adenosine diphosphate and epinephrine in platelet aggregation tests. Objectives: To identify common mutations through exome sequencing in two patients from the same family diagnosed with SPS and, thus, contribute to the molecular study of this disease. Materials and methods: Descriptive study. In January 2018, exome sequencing was performed in a 10-year-old patient treated at Fundación HOMI (Bogotá D.C., Colombia), index case, and in one of his adult first-degree relatives, both with a history of thrombotic disease and diagnosed with SPS. Exome sequencing was performed at the Complexo Hospitalario Universitario de Santiago de Compostela (Spain) using the SureSelect Clinical Research Exome V2 software by Agilent. Results: Exome sequencing led to detect genetic variants in both cases when compared with the reference sequence. The following variant was identified in the two samples: a cytosine to thymine transition at position c.236 (NM_000174.4) of the glycoprotein (GP)Ib-IX-V complex platelet membrane receptor, which causes a heterozygous transition of the amino acid threonine to isoleucine (i.e., a transition from hydrophilic amino acid to a hydrophobic amino acid) at position p. 79 of the extracellular leucine-rich repeat domain of GPIbα subunit of the (GP)Ib–IX complex, involving a conformational change of the main receptor of ligands IB alpha, which might result in platelet hyperaggregation and thrombosis. This variant has not been described in patients with SPS to date. Conclusion: The mutation identified in both samples could be related to SPS considering the importance of glycoprotein IX in platelet function.