The enzyme glucose 6 phosphate dehydrogenase is expressed in all tissues, where it catalyses the first step in the pentose phosphate pathway. Glucose 6 phosphate dehydrogenase deficiency is a common X-linked enzyme abnormality. It is prevalent throughout tropical and subtropical regions of the world because of the protection it affords during malaria infection. This deficiency is present in over 400 million people worldwide¹. Glucose 6 phosphate dehydrogenase deficiency is found in tropical and subtropical countries and is one of the important causes of haemolytic anaemia and neonatal jaundice².

Although most affected individuals are asymptomatic, there is a risk of neonatal jaundice and acute haemolytic anaemia, triggered by infection and the ingestion of certain drugs and broad beans (favism). Many different variants of glucose 6 phosphate dehydrogenase have been described. The vast majority of these are caused by single aminoacid substitutions³. This study was undertaken to see the frequency of this deficiency and the degree of anaemia caused by this defect in Riyadh, Saudi Arabia.

MATERIALS AND METHODS

A total of 1740 subjects aged 5 to 30 years referred from different hospitals and the ministry of interior to the Central Laboratory Riyadh, Saudi Arabia for detection of glucose-6-phosphate dehydrogenase deficiency, in one year, were included in this study. This laboratory is a reference centre and receives samples from whole Riyadh region.

Blood was obtained by venipuncture (5–10ml) in EDTA tubes. Glucose 6 phosphate dehydrogenase activity was determined by a screening test as described by Beutler².  Five µL of blood sample was mixed with 0.1 ml reagent solution containing NADP, oxidized glutathione and glucose 6 phosphate in a small test tube. After mixing well the sample was incubated for 10 minutes at 25 °C. Then 0.01 ml of the sample was applied in the form of a spot to the filter paper supplied along with the kit provided by Boehringer Manheim. After waiting for half an hour when the filter paper was dry, the blood spot was examined under a long wave UV-lamp in a darkened room.

Specimens obtained from patients with normal or just slightly depressed activity showed strong fluorescence. Lack of fluorescence after 10 minutes incubation suggested a total absence or marked deficiency of glucose 6 phosphate dehydrogenase. The anaemia was detected by doing RBC count and haemoglobin levels by SysMex 800 coulter machine. The cut off point for haemoglobin was 7 mg/dl. Out of a total of 1740 subjects 1365 (78.4%) were referred by the ministry of interior. As a routine, the Government of Saudi Arabia screens their subjects before marriage for the detection of glucose-6-phosphate dehydrogenase deficiency. Three hundred and seventy five subjects (21.6%) were referred from various hospitals. Therefore the subjects were basically two distinct groups, ‘marriage group’, and ‘hospital group’.

RESULTS

The age range was 5 to 30 years. Among the ‘marriage group’ 878 (64.3%) were males while 487 (35.7%) were females. The ‘hospital group’ had 235 (60%) males and 144 (40%) females.

Out of total 1740 subjects that were screened for Glucose-6-phosphate dehydro-genase deficiency 106 (6.09%) were deficient. In the marriage group (4.1%) were deficient (56/1365). Out of these 70% (34/56) were males while 30% (17/56) were females. In the hospital group 13.3% patients (50/375) had glucose-6-phosphate dehydrogenase deficiency. Out of these 50 patients, 30 (60%) were males while 20 (40%) were females. The relative distribution of this data is shown in table 1.

Table-1: Distribution of Glucose-6-phosphate dehydrogenase deficient patients in marriage and Hospital group.

In 54 glucose-6-phosphate dehydro-genase deficient subjects the red blood cell count and haemoglobin level was determined to see the degree of anaemia. Out of a total of 54 subjects studied 33 (61%) had anaemia. Eight subjects (14.8%) had severe anaemia, nine subjects (16.6%) were having moderate anaemia while sixteen (29.6%) had mild anaemia. The position of anaemia in these subjects is shown in table 2.

Month wise distribution of patients is seen in table 3. Maximum cases were recorded in the month of November, followed by decreasing number of cases in May, December and October respectively.

Table-2: Status of Anaemia in 54 subjects with glucose-6-phosphate dehydrogenase deficiency

Severe anaemia                =Hb <7.0g/dl.

Moderate anaemia        = Hb  7-10g/dl

Mild anaemia           = Hb 10-11g/dl

Table-3: Month-wise distribution of Glucose-6-phosphate dehydrogenase deficient subjects.

DISCUSSION

This study was conducted on Saudi population in the central capital region of Riyadh. The frequency of glucose-6-phosphate dehydro-genase deficiency varies in various areas of Saudi Arabia, which range from less than 5% in central area to 24% in Khyber. Our work has shown that the frequency of glucose-6-phosphate dehydrogenase deficiency in central area is 6.09%. This figure is higher than that reported by previous workers in the centre region⁴.

It was observed that the frequency of glucose-6-phosphate dehydrogenase deficiency in marriage group (4.1%) was significantly higher than the hospital group (13.3%). The frequency was much higher in males than females in both the groups. Similar observations have been reported by Joshi et al. from Western India⁵ and Sanpavat and his co-workers from Thailand⁶.

The overall incidence of anaemia due to glucose-6-phosphate dehydrogenase deficiency was higher (61%) in our study as compared to one reported from Thailand by Sanpavat et al⁶. Pietrapertosa and his associates from Bari (Italy) reported that 59.2% of their glucose-6-phosphate dehydrogenase deficient subjects were asymptomatic⁷. We studied the same number (54) of glucose-6-phosphate dehydrogenase deficient patients and observed that 39% of our glucose-6-phosphate dehydrogenase deficient subjects were without symptoms.

The higher frequency of anaemia in this region is due to genetic polymorphism of glucose-6-phosphate dehydrogenase.

Table-3 shows monthly distribution of glucose-6-phosphate dehydrogenase deficient patients. Although the fava bean season extends from February to June, maximum cases in our study were recorded in other months of the year. The same observations have been reported by Yahya et al. from India⁸ and Al-Ali from Dammam Saudi Arabia⁴. This study thus does not support causal relationship between the bean ingestion and haemolytic episodes in glucose-6-phosphate dehydrogenase deficient Saudis⁸. It has been documented by Warsy et al. that glucose-6-phosphate dehydrogenase Mediterran-ean variant was the type producing severe deficiency and causing haemolytic anaemia under oxidative stress⁹.

The need for utilizing screening measures for early detection of glucose-6-phosphate dehydrogenase deficiency before marriage is apparent. Since glucose-6-phosphate dehydrogenase deficiency in marriage group exists, there is compelling need for introducing measures such as genetic counselling and public health education as part of the overall health and welfare services in the area.

REFERENCES

1.        Metha A, Manson PJ, Vulliamy TJ. Glucose-6-phosphate dehydrogenase deficiency. Baillieres Best Pract Res Clin Haematol 2000; 13(1): 21-38.

2.        Mitchell BE. G6PD deficiency screening test. Blood 1968;32:816.

3.        Zarza R, Pujades A, Rovira A, Aymerisy M. Two new mutations of the glucose-6-phosphate dehydrogenase gene associated with hemolytic anemia. Br J Haematol 1997; 98(3): 578-82.

4.        Al-Ali AK. Common glucose-6-phosphate dehydrogenase variants from Saudi population and its prevalence. Annals Saudi Med 1996; 16(6): 654-57.

5.        Joshi SR, Patel RZ, Patel MR, Sukumar S, Colah RB. High prevalence of glucose-6-phosphate dehydrogenase deficiency in Vataliya Prajapati Community in Western India. Haematologia 2001; 31(1):57-60.

6.        Sanpavat S, Nuchprayoon I, Ungbumnet W. The value of methemoglogin reduction test for neonatal glucose-6-phosphate dehydrogenase deficiency. J Med Assoc Thai 2001; 84(1): 91-98.

7.        Pietrepertosa A, Palma A, Delios G, Tannoia N. Genotype and Phenotype correlation in glucose-6-phosphate dehydrogenase deficiency. Haematologica 2001; 86(1):30-35.

8.        Yahya HI, Al- Alawi NA. Acute haemolytic episodes and Fava bean  consumption in glucose-6-phosphate dehydrogenase deficient Iraqis. Indian J Med Res 1993; 98: 290-292.

Address for Correspondence and Reprints:

Prof. A S Khan Gandapur, Department of Pathology, Women Medical College, Abbottabad. Pakistan.

Email: wmcpk@doctor.com