Prevalence and molecular characterization of G6PD deficiency in two Plasmodium vivax endemic areas in Venezuela: predominance of the African A-202A/376G variant

Abstract

Background: Glucose-6-phosphate dehydrogenase (G6PD) deficiency causes acute haemolytic anaemia triggered by oxidative drugs such as primaquine (PQ), used for Plasmodium vivax malaria radical cure. However, in many endemic areas of vivax malaria, patients are treated with PQ without any evaluation of their G6PD status.Methods: G6PD deficiency and its genetic heterogeneity were evaluated in northeastern and southeastern areas from Venezuela, Cajigal (Sucre state) and Sifontes (Bolívar state) municipalities, respectively. Blood samples from 664 randomly recruited unrelated individuals were screened for G6PD activity by a quantitative method. Mutation analysis for exons 4-8 of G6PD gen was performed on DNA isolated from G6PD-deficient (G6PDd) subjects through PCR-RFLP and direct DNA sequencing.Results: Quantitative biochemical characterization revealed that overall 24 (3.6 %) subjects were G6PDd (average G6PD enzyme activity 4.5 ± 1.2 U/g Hb, moderately deficient, class III), while DNA analysis showed one or two mutated alleles in 19 of them (79.2 %). The G6PD A-202A/376G variant was the only detected in 17 (70.8 %) individuals, 13 of them hemizygous males and four heterozygous females. Two males carried only the 376A → G mutation. No other mutation was found in the analysed exons. Conclusions:The G6PDd prevalence was as low as that one shown by nearby countries. This study contributes to the knowledge of the genetic background of Venezuelan population, especially of those living in malaria-endemic areas. Despite the high degree of genetic mixing described for Venezuelan population, a net predominance of the mild African G6PD A-202A/376G variant was observed among G6PDd subjects, suggesting a significant flow of G6PD genes from Africa to Americas, almost certainly introduced through African and/or Spanish immigrants during and after the colonization. The data suggest that 1:27 individuals of the studied population could be G6PDd and therefore at risk of haemolysis under precipitating factors. Information about PQ effect on G6PDd individuals carrying mild variant is limited, but since the regimen of 45 mg weekly dose for prevention of malaria relapse does not seem to be causing clinically significant haemolysis in people having the G6PD A-variant, a reasoned weighing of risk-benefit for its use in Venezuela should be done, when implementing public health strategies of control and elimination.

Prevalence of glucose-6-phosphate dehydrogenase (G6PD) deficiency (A-376/202) in homozygous sickle cell patients in Senegal and its clinical impact

“…This difference would be related to the criteria of inclusion of the patients but especially to the method of detection which was rather biochemical. The male prevalence found in this study has been described by many authors including Vizzi et al (2016) in Venezuela, which found a prevalence of 5.5% in men as compared to 4.1% in women (p ˂ 0.007). Similar results were also obtained by Benkerrou et al (2013) with respectively 16% of men versus 10% with women.…”

Prevalence of glucose-6-phosphate dehydrogenase (G6PD) deficiency in malaria endemic region of Iran (Sistan and Baluchestan Province): Epidemiological profile and trends over time

“…According to the previous epidemiologic studies, the prevalence rate of G6PD deficiency is higher among males than females [11,27,[30][31][32][33][34][35]. In line with these studies, the current study also revealed a higher prevalence rate of G6PD deficiency among males compared to the females.…”

“…Also, in malarious regions of the world, the prevalence rate of G6PD deficiency was reported to be 8% on average [25] which is lower than that (12%) in the present study. Nevertheless, the prevalence rate of the current report is lower than that of some parts of the world including Zuniga in Honduran (16.8%) [26] and is higher than that of some other areas such as Venezuela (3.6%) [26,27]. Interestingly, rate of G6PD deficiency among study participants in southeast and north of Iran is considerably higher than that in south and central part of Iran [28,29].…”

Glucosa 6 fosfato deshidrogenasa en indígenas piaroas en zona endémica de malaria.

“…Ahora bien, si la mezcla génica fuera efectiva entre indígenas Piaroas e individuos de las ciudad (que la población indígena este integrada a la mestiza urbana y no aislada o desplazada), es de esperar deficiencia bioquímica de G6PD clase III, la que caracteriza a la población venezolana y que se corresponde con individuos con deficiencia enzimática de leve a moderada, en los cuales la sintomatología hemolítica es desencadenada únicamente por la exposición a sustancias que inducen estrés oxidante 18,39,40 .…”

“…Por tanto, un importante aspecto a considerar en estudios genéticos por el agravamiento de la hemolisis de eritrocitos, y en consecuencia del grado de anemia, es la determinación poblacional de G6PD en el tratamiento del paludismo, respecto a la posibilidad de aumento de la dosis o la prolongación del número de días de tratamiento en los casos de resistencia o recidiva, particularmente porque el descubrimiento de hemólisis en hombres con deficiencia de G6PD como resultado de tratamiento antimalárico con primaquina data de 1950, y especialmente cuando en 2016 se publica una prevalencia de 3,5% de deficiencia de G6PD en zonas venezolanas (Bolívar y Amazonas) endémicas de paludismo, en que se excluye a la población indígena por considerar escaso su flujo génico [11][12][13][14][15][16][17][18] . En este sentido, en Venezuela, de Acquatella desde 1966 19 no encuentra deficiencia de G6PD en indígenas paraujanos (de la Guajira venezolana), pero debido a la inesperadas cifras de sujetos con anemia hemolítica aguda en indígenas yanomamo (de las comunidades de Ocamo y Mavaca del estado Amazonas), poblaciones con amplia exposición a infección por paludismo y alta prevalencia de síndrome de esplenomegalia hiperactiva a Plasmodium spp., se llevan a cabo estudios para indagar la etiología de estos inusuales casos de anemia hemolítica severa, en que se demuestra que la condición hemolítica está asociada a aglutinación mediada por repuesta autoinmune y no a defectos hereditarios de membrana de eritrocitos, hemogloginopatías o deficiencia de G6PD u otras anormalidades enzimáticas asociadas con hemólisis [20][21][22] .…”