Molecular characterisation of sickle cell disease and classification of major haplotypes associated with the β-globin cluster (HBB gene) by means of SNP marker sequencing in a group of samples from Bolívar, Colombia.

Abstract

Background: Colombia has a mestizo population and the prevalence of haemoglobin variants varies according to each region, but heterozygous carriers can be found in all of them.

Aim: To characterise sickle cell disease (SCD) haematologically, biochemically, and molecularly, and detect classic haplotypes by DNA sequencing in a group of samples from Bolívar, Colombia.

Subjects and methods: Blood samples were collected after informed consent from volunteers from eight communities in the Bolívar department, plus samples from the Pacific region, Providencia Island, and Bogotá were included. Data were obtained from: (1) haematological analyses; (2) biochemical tests: dHPLC was used to determine haemoglobin (Hb); and (3) DNA sequencing data through five SNPs.

Results: 101 samples were identified by rs334 through Sanger's Sequencing, structural haemoglobinopathies HbAS (34.65%), HbSS (2.97%) and HbAC (1.98%) were found. When contrasting the Hb identification results between SNP rs334 Vs. dHPLC/Isoelectric Focusing (IEF), a coincidence was found in 39/43 samples analysed, therefore, when comparing these techniques, a significant correlation was found (Pearson's correlation coefficient r = 0.998). 26 samples previously analysed by rs334 were classified into classical haplotypes CAR (50.0%), BEN (30.76%), CAM (7.69%), SEN (3.84%), and ATP-I (7.69%).

Conclusions: SCD characterisation and SNPs-based classification through Sanger's DNA sequencing have not been performed before in Colombia. The results of this work will make it possible to expand the data or records of carriers and those affected, which will benefit patients and their families.