Background Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most prevalent inborn disorder. This X-chromosome-linked recessive disease affects more than 400 million people globally, and is associated with haemolytic anaemia after medication with the anti-latent malaria drug, primaquine. To prevent malaria, the Republic of Korea (ROK) Army administers malaria chemoprophylaxis. Due to the previously low G6PD deficiency prevalence in the ROK, prior to primaquine administration, testing for G6PD deficiency was not mandatory. In this study, to evaluate the risk from malaria chemoprophylaxis in the ROK, G6PD deficiency prevalence was investigated. Methods Blood specimens from 1,632 soldiers entering training camp for the 3 rd Infantry of the ROK Army were collected. CareStart™ Biosensor for G6PD and haemoglobin (Hb) was used to detect G6PD levels. G6PD variants using the DiaPlexC G6PD Genotyping kit (Asian type) and full-length sequencing were examined. Results Of 1,632 blood specimens tested, none was observed to be G6PD deficient. The median value of all tested samples was 7.582 U/g Hb. An investigation of 170 G6PD DNA variants was analysed and categorized as partially low normal [n = 131, 30–80% (2.27–6.05 U/g Hb)of the median value], high [n=3, >150% (>11.373 U/g Hb) of the median value], or normal [n = 36, 80–150% (6.05–11.373 U/g Hb) of the median value], and none was amplified by the DiaPlexC kit. Five silent mutations (C→T) in 38 partially abnormal specimens were found at the 1,311th nucleotide position by sequence analysis. Another 8 silent mutations (T93C) were also detected in 131 partially low normal specimens. Thus, it is inferred that these silent mutations could be related to G6PD activity. Conclusions This G6PD deficiency prevalence study, conducted among participants from the 3 rd Infantry of the ROK Army, provided crucial evidence for the safety of malaria chemoprophylaxis. This study showed found that the prevalence of G6PD deficiency among 1,632 young soldiers was wholly absent. Although G6PD phenotypic mutations were not detected, many silent mutations (C1311T and T93C) were observed. Thus, it is inferred that malaria chemoprophylaxis is relatively safe against G6PD deficiency-mediated haemolytic anaemia. However, given the number of individuals whose G6PD were at the low end of the normal range and the frequent detection of G6PD deficiency-related mutations, consistent monitoring of G6PD deficiency is needed. Keywords : Glucose-6-phosphate dehydrogenase deficiency, Prevalence, Single nucleotide polymorphism, Primaquine

Background: Malaria chemoprophylaxis using chloroquine and primaquine has been administered to resident soldiers in the 3rd Army of Republic of Korea (ROK) to prevent malaria infection since the year 1997. Due to mass chemoprophylaxis against malaria, concern exists about occurrence of chloroquine resistance. Herein, we investigated the single nucleotide polymorphisms (SNPs) of the Plasmodium vivax multi-drug resistance protein-1 (Pvmdr-1) gene to monitor the risk of chloroquine resistance.Methods: To evaluate the risk of malaria chemoprophylaxis, SNPs of the Pvmdr-1 gene were analysed in 73 soldiers of the 3rd Army of ROK diagnosed with infection by Plasmodium vivax. Results: Quintuple mutations (G698S, L845F, M908L, T958M, and F1076L) were detected in 73 soldiers. Mutation in the Y541C position was detected in soldiers at a frequency of 1.3% (1/73). In addition, silent mutations were detected at positions 44K, 493L, 529T, and 1233E. Based on these SNPs, Pvmdr-1 sequences of ROK were classified into 6 haplotypes. Phylogenetic analysis showed that the neighbourhood of the 6 haplotypes were Chaina_NB-16 and Papua New Guinea-PNG58 (Figure 1).Conclusions: Genetic- or phenotypic-based chloroquine resistance was not observed. However, various SNPs including a newly identified non-synonymous mutation (Y541C) have been introduced into Plasmodium vivax malaria endemic areas in ROK. Thus, to prevent the emergence of chloroquine resistance, continuous surveillance for SNPs of Pvmdr-1 related with chloroquine resistance is essential in the malaria chemoprophylaxis-executed regions of ROK.

Background: Malaria chemoprophylaxis using chloroquine (CQ) and primaquine (PQ) has been administered to resident soldiers in the 3rd Army of Republic of Korea (ROK) to prevent malaria infection since the year 1997. Due to mass chemoprophylaxis against malaria, concern exists about occurrence of chloroquine resistance (CQR). Herein, we investigated the single nucleotide polymorphisms (SNPs) of the Plasmodium vivax multi-drug resistance protein-1 (pvmdr-1) gene to monitor the risk of CQR. Methods: SNPs of the pvmdr-1 gene were analyzed in 73 soldiers of the 3rd Army of ROK diagnosed with infection by Plasmodium vivax (P. vivax). Results: Quintuple mutations (G698S, L845F, M908L, T958M, and F1076L) were detected in 73 soldiers. Mutation in the Y541C position was firstly detected in soldiers at a frequency of 1.3% (1/73). In addition, synonymous mutations were detected at positions K44, L493, T529, and E1233. Based on these SNPs, pvmdr-1 sequences of ROK were classified into 6 haplotypes. The phylogenetic analysis closed to Type of North Korean showed that P. vivax malaria of ROK could be a reason of influx from North Korea. In this study, there was no therapeutic resistance (CQ-mediated parasite clearance within 72 hours) for clinical samples that possessed various SNPs of pvmdr-1. Various SNPs including a newly identified non-synonymous mutation (Y541C) had been introduced into P. vivax malaria-endemic areas in ROK. Conclusions: Our study showed that synonymous and non-synonymous mutations of pvmdr-1 were introduced to the malaria chemoprophylaxis-executed regions of ROK from 2016 to 2017. Thus, to prevent the emergence of CQR, continuous surveillance for SNPs of pvmdr-1 related with CQR in the malaria-endemic regions of ROK is essential.

Background: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most prevalent inborn disorder. This X-chromosome-linked recessive disease affects more than 400 million people globally, and is associated with hemolytic anemia after medication with the anti-latent malaria drug, primaquine. To prevent malaria, the Republic of Korea (ROK) Army administers malaria chemoprophylaxis. Due to the previously low G6PD deficiency prevalence in the ROK, prior to primaquine distribution, testing for G6PD deficiency was not mandatory. Here, we investigate G6PD deficiency prevalence to evaluate the risk from malaria chemoprophylaxis.Methods: Blood specimens from 1,632 soldiers entering training camp for the 3rd Infantry of the ROK Army were collected. CareStart™ Biosensor for G6PD and Hemoglobin was used to detect G6PD levels. G6PD variants using the DiaPlexC G6PD Genotyping kit (Asian type) and full-length sequencing were examined.Results: Of 1,632 blood specimens tested, none were observed to be G6Pd deficient. The median value of all tested samples was 7.582 U/g Hb. An investigation of 170 G6PD DNA variants were analyzed and categorized as partially low (n=134, 30%–80% (2.27–6.05 U/g Hb) of the median value), high (n=3, >150% (>11.373 U/g Hb) of the median value), or normal (n=36, 4.6–13.5 U/g Hb), and none were amplified by the DiaPlexC kit. Five silent mutations (C→T) in 38 partially abnormal specimens were found at the 1311th nucleotide position by sequence analysis. Another 8 silent mutations (T93C) were also detected in 134 partially abnormal specimens. Thus, we inferred that these silent mutations could be related to G6PD deficiency.Conclusions: This G6PD deficiency prevalence study, conducted among participants from the 3rd Infantry of the ROK Army, provided crucial evidence for the safety of malaria chemoprophylaxis. Here, we found that the prevalence of G6PD deficiency among 1,632 young soldiers was nearly 0. Although G6PD phenotypic mutations were not detected, many silent mutations (C1311T and T93C) were observed. Thus, we inferred that malaria chemoprophylaxis is relatively safe against G6PD deficiency-mediated hemolytic anemia. However, given the number of individuals whose G6PD were at the low end of the normal range and the frequent detection of G6PD deficiency-related mutations, consistent monitoring of G6PD deficiency is needed.