Prevalences of inherited red blood cell disorders in pregnant women of different ethnicities living along the Thailand-Myanmar border

Abstract

Background: Inherited red blood cell disorders are prevalent in populations living in malaria endemic areas; G6PD deficiency is associated with oxidant-induced haemolysis and abnormal haemoglobin variants may cause chronic anaemia. In pregnant women, microcytic anaemia caused by haemoglobinopathies mimics iron deficiency, complicating diagnosis and treatment. Anaemia during pregnancy is associated with morbidity and mortality. The aim of this study was to characterise the prevalence of G6PD deficiency and haemoglobinopathies among the pregnant population living along the Thailand-Myanmar border. Pregnant women attending antenatal clinics in this area belong to several distinct ethnic groups. Methods: Data were available for 13,520 women attending antenatal care between July 2012 and September 2016. Screening for G6PD deficiency was done by fluorescent spot test routinely. G6PD genotyping and quantitative phenotyping by spectrophotometry were analysed in a subsample of women. Haemoglobin variants were diagnosed by HPLC or capillary electrophoresis and molecular methods. The prevalence and distribution of inherited red blood cell disorders was analysed with respect to ethnicity. Results: G6PD deficiency was common, especially in the Sgaw Karen ethnic group, in whom the G6PD Mahidol variant allele frequency was 20.7%. Quantitative G6PD phenotyping showed that 60.5% of heterozygous women had an intermediate enzymatic activity between 30% and 70% of the population median. HbE, beta-thalassaemia trait and Hb Constant Spring were found overall in 15.6% of women. Only 45.2% of women with low percentage of HbA 2 were carriers of mutations on the alpha globin genes. Conclusions: Distribution of G6PD and haemoglobin variants varied among the different ethnic groups, but the prevalence was generally high throughout the cohort. These findings encourage the implementation of an extended program of information and genetic counselling to women of reproductive age and will help inform future studies and current clinical management of anaemia in the pregnant population in this region.

Diagnostic performances of the fluorescent spot test for G6PD deficiency in newborns along the Thailand-Myanmar border: A cohort study

“…The highest prevalence of G6PD deficiency is found in malaria endemic regions 1 , 15 . In the population attending Shoklo Malaria Research Unit (SMRU) clinics, the prevalence of G6PD deficiency is 13.7% in adult males 16 and 2–4% in adult females 17 and neonatal hyperbilirubinemia is common 18 . Routine neonatal screening for G6PD deficiency is therefore recommended in this setting 9 .…”

Vivax malaria in pregnancy and lactation: a long way to health equity

“…It is expected that a fluorescent spot test (or an equivalent RDT) would classify heterozygous females with a G6PD activity as low as 30-40% as G6PD normal. In fact, Bancone et al found that 60% of G6PD heterozygous females were misdiagnosed by qualitative screening [28]. Due to the loss of G6PD-deficient cells to haemolysis during illness, heterozygote females with even less than 30-40% activity could be misdiagnosed as normal if the test is done Fig.…”

“…Since the previous quantification of the G6PD activity during the haemolytic episode was considered unreliable (due to increased reticulocyte count and low Hb level), the staff offered the woman to repeat quantitative G6PD testing while in steady state (HCT 36.1%). This time the G6PD activity was found to be 4.62 IU/gHb, which corresponds to 62% of the population mean and is highly suggestive of G6PD heterozygosity [28]. Following this new finding, the patient and infant were screened for the most common G6PD gene mutations seen in the area (Mahidol, Chinese-4, Viangchan, Mediterranean variants) [29].…”

Estimation of Malaria Parasite Densities by Different Formulas in Thailand

“…In this study, parasite density by assumed RBC count of 5.0 x10 6 /µL (for males) and 4.5 x10 6 /µL (for females) showed overestimation, possibly people living in Thailand including Thai and other ethnicities from Myanmar had underlying anemia due to hemoglobinopathy (which is commonly found) [13,14] and intestinal parasitic infection [15][16][17][18][19] causing lower exactly assumed RBC counts in these population in Thailand.…”