Erythrocytosis is defined as an increased concentration of erythrocytes, reflected in elevated haemoglobin and haematocrit. It is divided into primary, where the defect occurs in the bone marrow, and secondary, where causes outside the bone marrow lead to increased erythropoietin (EPO) production. Familial erythrocytosis (FE) is a form of erythrocytosis that results from a genetic defect. The EGLN1 gene encodes the PHD2 protein, which is one of the key enzymes of the human oxygen sensing pathway. Variants of the EGLN1 gene result in erythrocytosis type 3, which is characterised by low to normal serum EPO levels. Our study consisted of two parts. The first part was aimed at analysing the EGLN1 gene and creating a catalogue of EGLN1 variants associated with FE. The second part was aimed at establishing a diagnostic method to identify EGLN1 variants. We optimised the PCR reaction for selected regions of the EGLN1 gene in control samples and used this protocol to amplify DNA from five members from two families with suspected familial erythrocytosis. In one of the families, we found the EGLN1 c.471G>C (p.Gln157His) variant in both patients. In the other family, we detected the EGLN1 c.1072C>T (p.Pro358Ser) variant in both members with suspected DE, which was not present in the healthy family member. Further studies are needed to confirm the influence of the detected EGLN1 variants on the function of the protein.
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