Detection of 1311 polymorphism by microarray technique Table II. G6PD activity, the type of Gd-Med mutation and the genotype of 1311 polymorphisms in the study group Case no. and sex 1. Control G6PD activity [U/gHb] Approval from the institutional Ethics Committee of Cukurova University Medical Faculty was provided and informed consent was obtained from all subjects prior to enrolment in the study. Results A screening protocol was performed and of 450 subjects, 32 were found to have G6PD deficiency. Genomic DNA samples from these 32 G6PD- deficient individuals were analyzed, and 15 subjects were found to be hemizygous, five cases were homozygous, one case was heterozygous, whereas eleven subjects were shown to be the wild-type (Figure 1). That is, the percentage of the G6PD- deficient individuals with 1311 polymorphism was 4.7% in our study group. G6PD activity, fluorescence signal rate and molecular features of the cases are detailed in Table I and Table II. Discussion The presence of a mutation, a silent C-to-T change, at nucleotide 1311 in exon 11 of the G6PD gene was first noticed when DNA samples from subjects with G6PD Mediterranean (Gd-Med) mutation were sequenced by De Vita et al. [19]. Since then, 1311 polymorphism has been shown to be quite prevalent among G6PD-deficient people, particularly in those with Gd-Med mutation, and has been reported in many countries all over the world including Portugal, Pakistan, Sardinia, and Tunisia [20-23]. 1311 mutation has been considered as a poly- morphic marker of the G6PD gene, independent of G6PD deficiency. Nevertheless, studying the 1311 polymorphism in subjects with G6PD Mediter- ranean mutation could help us to recognize the spread of this mutation [24]. Using sequence analysis, Beutler and Kuhl studied the distribution of the nucleotide polymorphism C1311T in cases with and without G6PD deficiency in diverse populations in 1990. They found that out of 21 Gd- Med individuals from Mediterranean countries, 20 had a T at nucleotide 1311, whereas neither of two Gd-Med cases from the Indian subcontinent had 1311 polymorphism. The investigator concluded that the Gd-Med mutation may have arisen indepen- dently in Europe and in Asia, since the vast majority of European subjects with Gd-Med had 1311 polymorphism [14]. Moiz et al. reported that the 1311 polymorphism was seen frequently both in subjects with Gd-Med mutation and in healthy individuals in Pakistan [21]. Similarly, Sukumar et al. reported a high frequency of 1311 polymorphism in Gd-Med and G6PD Kerala- Kalyan Indians [24]. Using the PCR-RFLP technique, Nuchprayoon et al. identified the G6PD mutations in two different ethnic groups in Thailand, and 2. M 3. F 4. M 5. F 6. F 7. M 8. M 9. M 10. M 11. F 12. F 13. F 14. F 15. F 16. M 17. M 18. M 19. F 20. M 21. F 22. M 23. M 24. M 25. M 26. M 27. F 28. M 29. M 30. M 31. M 32. F 33. M reported that the 1311 polymorphism was common both in G6PD-deficient and in normal cases [25]. According to the data of Ruzzo et al. from Italy, in the normal population of southern Italy, which is at risk for Gd-Med mutation, the 1311 polymorphism was 16.7-20%, whereas in the Marche region, in central Italy, the 1311T frequency was found to be about one half of that found in southern Italy [26]. In Great Britain, the incidence of this silent mutation Arch Med Sci 4, August / 2011 589 Gd-Med mutation – Genotype 1311 Control Hemizygous Hemizygous Heterozygous Normal Hemizygous Hemizygous Hemizygous Hemizygous Heterozygous Hemizygous Hemizygous Hemizygous Hemizygous Homozygous Normal Normal Normal Normal Normal Normal – 0.0 3.7 0.0 2.3 4.6 0.0 0.0 0.0 0.0 0.0 4.1 1.5 3.6 2.8 0.0 0.0 0.0 3.9 0.0 4.9 0.0 0.0 0.0 0.0 0.0 2.3 0.0 0.0 0.0 0.0 4.2 0.0 Heterozygous Heterozygous Heterozygous Homozygous Heterozygous Homozygous Heterozygous Normal Hemizygous Hemizygous Hemizygous Hemizygous Hemizygous Hemizygous Heterozygous Homozygous Hemizygous Hemizygous Heterozygous Homozygous Hemizygous Hemizygous Hemizygous Hemizygous Hemizygous Normal Hemizygous Hemizygous Hemizygous Hemizygous Heterozygous Homozygous Hemizygous Hemizygous Hemizygous Hemizygous Hemizygous Hemizygous Hemizygous Hemizygous Heterozygous Hemizygous Normal Normal