Cyclic thrombocytopenia (CTP) is a rare disease characterized by the oscillations
seen in the platelet count of the patients. The pathomechanism of the disease is poorly
understood, several pathological processes have been implied in the background of
CTP. In our current study, we aimed to thoroughly investigate the case of a 41-year-old
female patient with a 22-year history of CTP. Wide-ranging laboratory testing, histological
analyses and genetic investigations were carried out to investigate all the defects
and alterations of physiological pathways described in the background of CTP to date.
Bone marrow biopsy showed normal hemopoiesis with the abundance of megakaryocytes,
some of which displayed hypolobulated nuclei. T-cell receptor rearrangement studies
showed a polyclonal pattern with no indication of a monoclonal cell population. Flow
cytometric assessment of the platelets revealed large number of immature platelets
and decreased expression of glycoprotein IIb and IIIa at platelet zenith. Increased
expression of glycoprotein IIb, IIIa and glycoprotein Ib-IX complex was observed at
the nadir of the cycle. Whole exome sequencing revealed a heterozygous missense variant
of uncertain significance in the SERPINC1 gene, which has been associated with hereditary
antithrombin deficiency. The screening of autoantibodies did not reveal signs of autoreactive
processes, and no thyroid dysfunction was found. Furthermore, synchronization with
the menstrual cycle could not be concluded based on our patient’s case. With our results
we contribute to the very limited data known about the long-term course of the disease
and provide valuable insights into the genetic architecture of CTP.
