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Higher prevalence of glucose-6-phosphate dehydrogenase (G6PD) deficiency in tribal population against urban population: a signal to natural selection

Ishani Shah, Jummanah Jarullah, Soad Al Jaouni, Mohammad Sarwar Jamal, Bushra Jarullah

Background: Human genetic variation is interlinked to genetic drift and gene flow. Interplay amongst these leads to evolution in natural populations. Studies suggest that Glucose-6- Phosphate Dehydrogenase (G6PD)-deficient alleles show some signatures of selection. Deficiency in G6PD is the most common enzyme deficiency of human erythrocyte which affects over 400 million people worldwide. There is no comprehensive information available about the prevalence of this disease across the entire map of Gujarat, India.

Methods: Cross-section retrospective study was conducted to determine prevalence of G6PD deficiency in population of Gujarat. 3467 samples from different hospitals throughout the state of Gujarat from September 2014 to September 2015 were analyzed. The G6PD activity was measured quantitatively by spectroscopic absorbance at 340 nm in kinetic mode.

Results: The drastic variation in the prevalence amongst the tribal and urban population was observed. Frequency varied from 11.18% in tribal populations to as low as 1.2% in the urban population. Urban areas such as Kutch, Bhuj, Lunawada and Kapadwanj showing relatively high prevalence have been known to be inhabited by tribal population.

Conclusions: Heterozygosity levels, linkage disequilibrium patterns and frequencies of alleles segregating in a population play a vital role in the prevalence of any genetic deficiency. However how this polymorphism is being maintained is not deciphered yet. Our study signals the need for rigorous research to understand the pattern of natural selection and establishment of selection coefficients for different genotypes.