# Amplicon-based DNA sequencing to characterize Duffy antigen polymorphisms and analysis of Duffy blood system and glucose-6-phosphate dehydrogenase deficiency in Mauritania

## TL;DR

This study examines the prevalence of Duffy antigen and G6PD deficiency in Mauritania to guide malaria treatment strategies.

## Contribution

The study provides updated epidemiological data on Duffy antigen polymorphisms and G6PD deficiency in different ethnic groups in Mauritania.

## Key findings

- Duffy-negative phenotype is predominant in individuals of black African ancestry (65–88%), while only 16% of white Moors are Duffy-negative.
- Among white Moors, 10.5% of Duffy-negative individuals are G6PD A– deficient, mostly heterozygous females.
- Most white Moors are Duffy-positive and eligible for primaquine therapy, while individuals of black African ancestry require G6PD screening before treatment.

## Abstract

Both Duffy blood antigen expression and G6PD deficiency are known to be associated with ethnic origin. Updates in epidemiological data on the prevalence of polymorphisms in these two human genes are key information for guiding national programs to eliminate Plasmodium vivax malaria.

Duffy genotypes and their predicted phenotypes were determined in 943 blood samples from Mauritanian patients belonging to different ethnic groups (n = 432 White Moors and n = 511 individuals of black African ancestry) with a known G6PD genotype determined by PCR-restriction fragment length polymorphism in our previous study, using a cost-saving multiplexed barcoding technique that allows simultaneous analysis of a large number of samples and next-generation DNA sequencing (NGS).

Duffy-negative phenotype predicted from Duffy genotype was predominant in individuals with black African ancestry (65–88%), while 16% of white Moors were Duffy-negative. Among 432 samples with interpretable Duffy sequence data from white Moors, 7/356 (2.0%) were Duffy-positive and G6PD A– deficient; 8/76 (10.5%) were Duffy-negative and G6PD A– deficient, mostly (n = 6) in heterozygous females. By contrast, among 511 patients of black African ancestry, 13 (13/140, 9.3% including heterozygous females) were Duffy-positive and G6PD A– deficient; 65 (65/371, 17.5%) were Duffy-negative and G6PD A– deficient, mostly (n = 44) in heterozygous females.

A large majority of white Moors are Duffy-positive and susceptible to P. vivax infection, but most are eligible for anti-hypnozoite therapy with primaquine at the standard dose. About 15.4% of individuals with black African ancestry were affected by G6PD A– deficiency, independently of their Duffy receptor status. This population requires G6PD screening before primaquine therapy in rare cases of P. vivax infection. These results provide important clues about the feasibility to implement an efficient anti-hypnozoite treatment in Mauritania and identify priority areas for targeted interventions against P. vivax malaria.

Despite progress achieved in controlling malaria, several challenges remain, including Plasmodium vivax malaria. In most cases, this malaria species infects humans with the blood receptor called Duffy antigen (referred to as “Duffy-positive” individuals). After the initial infection, some P. vivax parasites (called hypnozoites) have the peculiarity of remaining dormant in the liver cells of incompletely treated patients for months or years before ‘waking up’ to cause other blood infections (called relapse) and spreading the disease. There is an effective medication to kill hypnozoites, but this pill can cause serious side effects in persons with insufficient activity of the enzyme called glucose-6-phosphate dehydrogenase (G6PD) due to mutations. Mutations that influence G6PD activity and determine the presence (or absence) of Duffy blood antigen depend largely on ethnic groups (and sex, for G6PD). Such mutations, in turn, affect the medical decision on whether anti-hypnozoite medication can be given or not to prevent relapse. We studied the proportions of Duffy-positive and Duffy-negative individuals to predict which ethnic groups are more susceptible to develop P. vivax and further predict the proportion of patients who can receive anti-hypnozoite medication safely in Mauritania. This epidemiological study attempted to identify which individuals should receive anti-hypnozoite treatment with priority.