Biochemical and Molecular Genetic Characterization of G6PD Deficiency in Newborn, Benin

Abstract

Background: In Benin, the diagnosis of G6PD deficiency is based on the biochemical test performed by the quantitative spectrophotometry assay of the enzymatic activity. We used the results of the molecular gene test to verify the reliability of the biochemical diagnostic test. The distribution of genes polymorphism associated with the G6PD deficiency in neonates is also determined throughout the country. Material and Methods: This is a crosssectional descriptive study carried on with 178 neonates aged ≤7 days. Blood samples were screened for quantitative G6PD enzymatic activity using Cypress Diagnostics kit (Cypress Diagnostics, Belgium). G6PD genotype analysis was performed using specific primers for PCR amplification of G6PD gene containing the common African mutations A376G, G202A, A542T, and T968C. We used Chi-2 test to compare the means of qualitative data and Student’s t-test to ascertain difference between group’s characteristics. A p-value of <0.05 was deemed significant. Results: The mean value of normal G6PD activity was 16.25 U/g Hb. Enzyme activity was significantly lower in female newborns of genotype A-(376/202) /A-(376/202) (p<0.01) and in males genotype A-(376/202) (p<0.001). The probability of being deficient when the test of enzymatic activity is positive among the true deficit (Se) was 0.42. The probability of being non-deficient when the test is negative among the non-deficient (Sp) was 0.89, that of being deficient when the test is positive (PPV) was 0.52 and the probability of being non-negative when the test is negative (VPN) was 0.85. Genotypes B/B, A/B, A/A, A-(376/202)/B, A-(376/202)/A, A-(376/202)/A-(376/202) were identified in female newborns with respective proportion of 39.56%, 13.19%, 7.69%, 24.18%, 13.19% and 2.20%. In males, 64.37% were genotype B, 9.20% genotype A and 26.44% genotype A-(376/202). The northern departments had the highest frequencies of G6PD A-(376/202) (33.18% to 37.73%) while the lowest levels were seen in the south (25.58% to 28.62%). Conclusion: Enzymatic activity showed good diagnostic value in male subjects but not in heterozygous female. The highest frequency of G6PD A-(376/202) mutation was in the North Benin.