Abstract
In this study we aimed to determine the prevalence of glucose-6-phosphate dehydrogenase (G6PD) deficiency in a Lebanese population and the clinical outcomes and associated adverse events encountered amongst affected patients. Newborn screening in a tertiary care centre in North Lebanon showed a prevalence of 2.1% (62 out of 3009), significantly higher in males than females, and in Muslims than Christians. Among 45 infants followed for a median of 2.2 years from birth, 12 (27%) were admitted to hospital for severe haemolytic crises, despite a programme of early family education and close follow-up. A nationwide newborn screening program to identify afflicted individuals, and to augment vigilance about this disease, should be considered in countries where the disorder is prevalent.
Background
Methods
Of 6772 babies born between January 2006 and December 2010 in Nini Hospital in Northern Lebanon, 3009 were screened for G6PD deficiency. All parents had given consent for the screening, and Institutional Review Board approval was sought and received. Screening was performed using a modified Beutler semi-quantitative test 4 on blood dried for 10 minutes on an S&S® 903 filter paper, and then transferred to Whatmann® no. 1 filter paper with and without ammonium sulfate. A visual fluorescence spot on a UV lamp was compared with a Sigma® deficient control. In screen positives a diagnostic test was performed using the MEDICON G-6-PDH set of reagents: 0.9 ml of Saponin 0.2% were added to 0.1 ml of sample blood collected on ethylenediaminetetraacetic acid, incubated for 10 minutes at room temperature, then allowed to react with glucose-6-phosphate and nicotinamide adenine dinucleotide phosphate, with results read by spectrophotometry at 340 nm. This test yields a positive G6PD deficiency result when the residual activity of red blood cells is less than 20% of normal. 5 Demographic data were also collected.
All G6PD-deficient infants were followed in the Paediatric Haematology Clinic until August 2011. All hospitalizations for a haemolytic event were recorded. Families of affected newborns were educated about the disease, the symptoms and signs of severe haemolysis and the importance of preventing haemolysis by avoiding the aggravating factors.
Results
Of the 3009 neonates screened, 62 (2.1%) (49 males and 13 females) were G6PD-deficient. Prevalence was 3.1% in males compared with 0.9% in females. There was a higher prevalence of G6PD deficiency among Muslims (2.6%) than among Christians (1.3%), consanguineous marriages being more common in Muslims.
Families of 45 of the 62 affected neonates were offered follow-up every 4–6 months. The neonates were followed for a median period of 2.2 years (range 0.7–5 years). At the age of one year, mean haemoglobin (Hb) in these infants was 10.4 g/dl. During follow-up, 12 (27%) of the 45 infants needed hospitalization for a severe haemolytic crisis (Hb < 7g/dl) and 10 of them needed urgent packed red blood cell transfusions (none had more than one admission). Mean Hb at hospitalization was 4.6 g/dl. The precipitating causes of the 12 haemolytic crises were febrile illness in four, maternal fava bean ingestion during breastfeeding in five, and intake of falafel (ground chickpea and fava bean mixture) in three. None of the haemolytic crises were attributed to ingestion of fava beans only.
Discussion
Previous studies have estimated the prevalence of G6PD deficiency in Lebanon to be between 1.0% and 3.1%, with no cases in the Druze and Aramians, 6 , 7 the variation reflecting different proportions of Muslims in different regions (consanguineous marriages being more common in Muslims). The higher prevalence of G6PD deficiency among males in our study (3.1%) conforms with the study by Taleb et al., but is three times higher than what was reported by Khneisser et al. 6 , 7 Males consistently had higher prevalence than females between 2006 and 2010. However, the spot fluorescence test for G6PD deficiency detection often misses partially deficient females with residual red blood cell activity of 20–60%, 5 , 8 so prevalence could be underestimated in females.
G6PD-deficient individuals around the Mediterranean basin share the same mutation, 9 indicating a low rate of new mutations.
Because consumption of raw and dry fava beans and food mixtures containing fava beans is common in Lebanon, the population is at a higher risk of developing favism (acute haemolytic anaemia post fava bean ingestion). The common practice of prolonged breastfeeding beyond the first year of life and the early introduction of solid food before six months of age in Lebanon are additional aggravating factors for favism. In the absence of transfusions, the favism-induced mortality rate can be as high as 8%. 10 , 11
In our study, G6PD deficiency-associated severe haemolytic anaemia was seen in infancy and early childhood. Despite neonatal screening and repeated instructions to parents not to feed their children fava beans or its derivatives, and to avoid such products during breastfeeding, the rate of emergency hospitalization for severe anemia remained relatively high at 27% (12/45) (26.6%). However, four of the 12 hospitalizations were related to risk factors that cannot be modified by family education, mainly febrile illnesses. Some parents failed to follow instructions and abstain from providing fava bean mixtures (but not fava beans only) to their children in our tertiary care centre. Parental education to avoid all dietary oxidants and on the symptoms of severe haemolysis and the need to seek urgent medical attention once they occur are crucial measures for the control of this highly prevalent disorder. Our study suggests that a free-of-charge screening programme for G6PD deficiency and focused nationwide awareness campaigns about favism and its consequences should be initiated in Lebanon in order to stimulate vigilance among affected families.