Detection of sickle cell hemoglobin in Haiti by genotyping and hemoglobin solubility tests

Abstract

Sickle cell disease is a growing global health concern because infants born with the disorder in developing countries are now surviving longer with little access to diagnostic and management options. In Haiti, the current state of sickle cell disease/trait in the population is unclear. To inform future screening efforts in Haiti, we assayed sickle hemoglobin mutations using traditional hemoglobin solubility tests (HST) and add-on techniques, which incorporated spectrophotometry and insoluble hemoglobin separation. We also generated genotype data as a metric for HST performance. We found 19 of 202 individuals screened with HST were positive for sickle hemoglobin, five of whom did not carry the HbS allele. We show that spectrophotometry and insoluble hemoglobin separation add-on techniques could resolve false positives associated with the traditional HST approach, with some limitations. We also discuss the incorporation of insoluble hemoglobin separation observation with HST in suboptimal screening settings like Haiti.

Figure 1.

A representative figure of the traditional hemoglobin solubility test (HST) with the blood samples in the phosphate buffer solution in transparent glass vials to allow the observation of turbidity that forms when sickle hemoglobin is present. Positive and negative samples are denoted by “+” and “−”, respectively.

Figure 2.

Examples of separation of insoluble hemoglobin in blood-phosphate buffer solution. Pictures were taken after spectrophotometry readings, which required a portion of the solution, and resulted in the variable volume of solution observed in this figure.

Figure 3.

Distribution of spectrophotometric values across hemoglobin solubility test (HST) values by genotype results. Red triangles and open blue circles represent the sickle cell hemoglobin (HbS) and non-HbS group, respectively.