Comparing G6PD Tests Using Capillary Blood Versus Venous Blood

In this study we propose to determine the correlation in glucose-6phosphate dehydrogenase enzyme activity in capillary blood obtained from a finger stick versus a venous blood specimen. As secondary endpoints we will seek to correlate phenotype as determined by quantitative and qualitative G6PD test, genotype as determined by PCR and DNA sequencing with flow cytometry. The secondary endpoints are critical for the design of G6PD diagnostic test evaluation studies.

In this study we propose to determine the correlation in glucose-6 phosphate dehydrogenase enzyme activity in capillary blood obtained from a finger stick versus a venous blood specimen. We will also compare results of different G6PD tests with known G6PD genetic profiles. The results of the study will inform design of future G6PD diagnostic development & evaluations. This research will be conducted in MaeSot Thailand, where G6PD deficiency has a high prevalence. Study participants will be recruited into three groups of 50 volunteers per group: 50 G6PD-deficient individuals, 50 G6PD-normal individuals, and 50 G6PD-intermediate individuals. Following a written informed consent, participants will donate about 3 ml of venous blood and about 4 drops of capillary blood (fingerstick). There will be no direct benefit to research participants.

Comparison of the performance of the Trinity quantitative test using capillary blood, vs the performance of the same test using venous blood.

Percent agreement between the quantitative results of the flow cytometry assay and the quantitative results of the spectrophotometric assay.

Categorical accuracy of a flow cytometry-based G6PD test against the spectrophotometric gold standard and genotyping

Using a predefined cutoff to categorize values from each quantitative test, determine percent agreement within each category between the two tests.

Compare sensitivity & specificity of qualitative results of the G6PD test and the categorical results of the quantitative spectrophotometric assay.

Percent agreement between the qualitative G6PD test and the categorical results of the spectrophotometric gold standard

Inclusion Criteria: Previous G6PD test at SMRU clinic Patient willing to participate and sign informed consent form Patient willing to allow donated sample to be used in future research Subjects 18 years of age or older Exclusion Criteria: patients with severe malaria or other severe illness Patients who received a blood transfusion in the last 3 months Patients who received primaquine in the past 1 month (this is to ensure that previous characterization of phenotype in the healthy subject has not been influenced by a recent hemolytic reaction)