BRIEF COMMUNICATION Prevalence of glucose-6-phosphate dehydrogenase deficiency in Northern Greece G. Ntaios, 1 A. Chatzinikolaou, 2 C. Tomos, 2 C. Manolopoulos, 2 P. Karalazou, 2 A. Nikolaidou 2 and S. Alexiou-Daniel 2 1 First Propedeutic Department of Internal Medicine and 2 Department of Microbiology, AHEPA Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece Key words glucose-6-phosphate dehydrogenase deficiency, lyonization, Mediterranean variant. Correspondence George Ntaios, First Propedeutic Department of Internal Medicine, AHEPA Hospital, Aristotle University of Thessaloniki, S. Kiriakidi 1, 54636 Thessaloniki, Greece. Email: ntaiosgeorge@yahoo.gr Received 11 June 2007; accepted 27 September 2007. doi:10.1111/j.1445-5994.2007.01618.x Abstract Glucose-6-phosphate dehydrogenase (G6PD) deficiency affects more than 400 million persons worldwide. Its distribution varies significantly among differ- ent geographic regions and different population groups. Purpose of our study was to estimate its prevalence in Northern Greece. The dataset comprised 5161 newborns and adults who were screened for G6PD deficiency between July 2001 and March 2007. G6PD deficiency was detected by the dye reduction method. In the screened group, 6.3% of subjects were G6PD deficient. Moderate enzyme deficiency was shown in 139 individuals (2.7%). Complete deficiency was identified in 3.7%. The prevalence of G6PD deficiency in Northern Greece is much higher compared with the general Greek population. Moreover, G6PD prevalence in the male sex is much higher – almost double – that in the female sex. Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most frequent enzymopathy in humans, affecting more than 400 million persons worldwide. 1 Its distribution varies significantly among different geographic regions and different population groups and is correlated to the historical prevalence of malaria, suggesting that its fre- quency was progressively increased through natural selection by malaria. 2–4 Indeed, its prevalence is high only in tropical and subtropical areas where malaria was hyperendemic. For example, its prevalence is 60–70% in Kurdish Jews, 5–7 21% in male African Bantus, 8,9 0.8% in Turkey 10 and 0.1% in Japan. 11 G6PD catalyses the initial step of the hexose mono- phosphate shunt, which leads to the reduction of nicotin- amide adenine dinucleotide phosphate (NADP) to NADPH. The latter is required for the generation of reduced gluta- thione, which is a sulfhydryl-containing tripeptide that functions as an intracellular reducing agent against injury by oxidants like hydrogen peroxide (H 2 O 2 ). Such oxidants are continuously formed either within red blood cells through reaction of haemoglobin with oxygen or exoge- nously caused by infections or drugs. 12 G6PD deficiency is an X-linked recessive disorder of metabolism. The 15-kb-long gene is located on band q28. 5,13 More than 140 different mutations of the G6PD gene have been identified. 14 The G6PD Mediterranean variant accounts for the 77% of the G6PD-deficient sam- ples of Hellenic origin. 15 Healthy persons of both male and female sexes have the same enzyme activity, although the latter have two X chromosomes per cell. Lyon hypo- thesis offers an explanation to this issue, suggesting that only one of the X chromosomes is active in each red cell precursor in the female human. 16 G6PD deficiency affects mainly the male sex. Heterozygous individuals of the female sex are usually clinically normal, although their enzyme activity may be normal, moderate or significantly reduced. 6 The purpose of the present study was to estimate the prevalence of G6PD deficiency in Northern Greece. The dataset was collected from the records of the Micro- biology Department of AHEPA University Hospital in Thessaloniki, Greece. It comprised 5161 newborns and Funding: None Potential conflicts of interest: None Internal Medicine Journal 38 (2008) 204–206 204 ª 2008 The Authors Journal compilation ª 2008 Royal Australasian College of Physicians