This study showed an allelic frequency of 3.6% for
G6PD-
Med in subjects infected with malaria in Southern Pakistan and 2.8% in all tested individuals. This is lower than average allelic frequency reports for G6PD deficiency from various regions of Pakistan. But considering that only one G6PD mutation (
G6PD 563c.C>
T) was looked for, we would have captured 80% of the G6PDd prevalence. Other G6PD variants reported from Pakistan were G6PD Orissa and Chatham [
9], for which gene-primaquine interaction is not known [
12]. Literature review showed that there were 15 national surveys [
13‐
27] with an average of 200 individuals per survey. Studies done so far from 1966 to date showed a frequency of 3.9% (range 1.1–8.5%) for G6PDd in Northern Pakistan. Highest frequency was observed in Pashtun males as 5.3% compared to Punjabis (3.3%), Sindhis (2.7%) and Mohajir (2.2%) males (Table
3). This G6PDd frequency is comparable with global G6PD map computed by Howes et al. in 2012 [
28]. The data for females was not analyzed as they were underrepresented in all studies.
Table 3
Allele frequency for
G6PDd in multi-ethnic males in Pakistan [
13‐
25,
27]
Pashtun | 1321 (17.0) | 84 (6.4) | 0.0636 |
Punjabi | 3227 (43.5) | 71 (2.2) | 0.0220 |
Sindhi | 397 (5.4) | 11 (2.8) | 0.0277 |
Baloch | NA | NA | NA |
Bengali | 146 (2.0) | 2 (1.4) | 0.0137 |
Kashmiri | 460 (6.2) | 5 (1.1) | 0.0109 |
Mohajir | 45 (0.6) | 1 (2.2) | 0.0222 |
Miscellaneous | 1817 (24.5) | 115 (6.3) | 0.0633 |
Total | 7750 (100) | 592 (3.9) | 0.0390 |
Gething et al. in 2011 estimated
P. falciparum transmission globally through mathematical modeling [
29]. Accordingly, 1.13 and 1.44 billion people, respectively, were at risk of stable and unstable malaria worldwide in 2010. In this model, Punjab, Gligit Baltistan, some areas of Baluchistan and Sindh were depicted as having a low annual incidence of < 1 malaria case in a population of 10,000 [
30]. Khyber Pakhtunkhwa (KPK) and majority of Sindh were evaluated to have stable malaria transmission having a prevalence of > 1:10,000 population [
30]. There is also high transmission of malaria in districts bordering Afghanistan and Iran that carry 37% of national malaria burden with an annual incidence exceeding 4.5 cases/1000 population [
31]. Interestingly, largest number studies to date are from KPK which show a high incidence of G6PD deficiency with an allele frequency of 0.241. This indirectly indicates that G6PD deficiency does not provide absolute immunity against infection with
P. falciparum. This was observed in the current study as well, as four of 110 patients with falciparum malaria had
G6PD 563c.C>
T mutation and were not immune to malaria. Moreover, the G6PDd malaria patients had high parasite burden of 152,821.00 ± 259,297.01/μL in this study. In contrast, Guindo et al. reported protective effect of
G6PD A-
type in African males against falciparum infection [
6]. The variance may be due to predominance of
G6PD 563c.C>T in Pakistani population that may have different effect on
P. falciparum survival than that observed in
G6PD A-African population. More studies are needed on the immunity (if any) conferred by
G6PD 563c.C>T against
P. falciparum in hemizygous males and heterozygous females.
G6PD 563c.C>
T is highly prevalent in West Asia including Pakistan [
12]. This mutation causes severe haemolysis when challenged with primaquine. This may be life threatening leading to renal failure and death [
12]. The effect of primaquine therapy on females who are carriers for this mutation is not known. Currently, safe alternatives for primaquine therapy are not available [
3]. Therefore, mandatory G6PD testing is the only option for Pakistan before intervening for malaria eradication with primaquine. More studies are needed on genome sequencing for identifying G6PD variants in Pakistan. This information can be used in developing an in-house point-of-care testing device for phenotype-genotype analysis and correct mapping of G6PDd. It can be incorporated in the mandatory neonatal screening as is available for hypothyroidism in Pakistan.