Identification of polymorphisms related to fetal hemoglobin increase and association with HbF values and variability of F cell distribution

• Grant number: 22/00429-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2022
• End date: September 30, 2022
• Field of knowledge: Health Sciences - Medicine - Medical Clinics
• Principal Investigator: Fernando Ferreira Costa
• Grantee: Beatriz Siqueira Ribeiro
• Host Institution: Centro de Hematologia e Hemoterapia (HEMOCENTRO). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil
• Associated research grant: 19/18886-1 - Pathophysiological mechanisms and treatment of red blood cell abnormalities, AP.TEM

Abstract

In healthy adults, fetal hemoglobin (HbF) levels are residual, but in some circumstances, there may be a variation with higher levels (0.8 to 5%), and this condition is called hereditary heterocellular persistence of HbF. In sickle cell disease (SCD), the increased expression of HbF during adulthood can improve the clinical course of the disease and prolong the life expectancy of these patients. However, the correlation between total HbF level and disease severity is not direct, due to the heterogeneous distribution of this hemoglobin between cells. Among the numerous molecular alterations that interfere in the expression of the gamma-globin genes (HBG), there is the presence of polymorphisms in the HBG2 (XmnI) and BCL11A genes, and the HBS1L-MYB intergenic region. These polymorphisms can alter several molecular mechanisms as well as the binding sites of transcription factors, causing fetal hemoglobin to continue to be expressed. Therefore, the estimation of the number of F cells, concentration of total and individual HbF in each F cell, and distribution of these cells, in addition to the investigation of molecular changes associated with the increase in fetal hemoglobin, may be relevant as complementary analyzes in the follow-up of patients with the disease sickle cell disease and that can be correlated with the clinical and laboratory evolution of these individuals. The objective of this work is to identify the BCL11A (rs1427407 and rs6545816), XmnI-HBG2 (rs7482144), and HBS1L-MYB (rs66650371) gene polymorphisms and to correlate HbF values and Fcell distribution in addition to the clinical presentation of patients with sickle cell disease. The results obtained may contribute to a better understanding of the pathophysiology of FD and to the monitoring of patients who make therapeutic use of hydroxyurea.(AU)