Erythrocytosis is a state of elevated levels of erythrocytes, hemoglobin and hematocrit. The inherited type of this disorder is called familial erythrocytosis (FE). Erythrocytosis can be divided into two major types– primary where there is a defect intrinsic to the erithroid cells in bone marrow, and secondary where there is a defect outside of the bone marrow. There are many genes involved in this disease, including HBB, which encodes information for a beta hemoglobin subunit. Hemoglobin is an oxygen transport protein in erythrocytes and can cause secondary FE. Main goal of the present study was to characterise the HBB gene in association to FE and to develop a diagnostic method for detection of sequence variants of HBB in patients suspected to have FE. HBB sequence variants and regions associated with FE were determined by literature and databases review. The coding regions of the gene and their flanking sequences were amplified using the PCR method and Sanger sequencing was used for determination of the nucleotide sequence of patients from two families with FE and a healthy control. Three polymorphisms were found in all patients and in a healthy family member, one in the coding region and two in the intronic region, none of which were previously associated with FE. Further analysis should be performed to determine the effect of the sequence variant found in the coding region. We have successfully established the protocol for diagnostic sequencing of the HBB gene in patients with FE.
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