Genetic Blood Disorders Survey in the Sultanate of Oman.J Trop Pediatr. 2003 Jul; 49 Suppl 1:i1-20.JT
The Genetic Blood Disorders Survey is the first community-based survey in the Arabic world and the Middle East to determine the prevalence of the most common genetic blood disorders. The objective of the survey was to determine the prevalence of the most common genetic blood disorders reported among Omani children under 5 years of age in order to provide the planners and policy-makers with reliable information suitable for formulating health policies, planning, and evaluation. The survey was designed, executed, and financed by the Ministry of Health of the Sultanate of Oman. To reduce costs and save effort and time, data collection for the survey was implemented with the Gulf Family Health Survey (GFHS). The GFHS in the Sultanate of Oman is a research project undertaken by the Council of Health Ministers of the Gulf Co-operation Council States. The six member countries have participated in this GFHS project. A total of 6103 households were interviewed. From these households 6342 children under 5 years of age were taken by their parents to neighbourhood hospitals or health centres for blood collection. Fifty-one per cent of the sample were male and 49 per cent were female. Among the child respondents, 17.9 per cent were in the age group 0 to < 1 year, 20.3 per cent were in the age group 1 to < 2 years, 21.1 per cent were in the age group 2 to < 3 years, 20.5 per cent were in the age group 3 to < 4 years, and 20.2 per cent were in the age group 4 to 5 years. Fifty-five per cent of the mothers of the children studied were illiterate, 9 per cent could read and write but had less than primary education, 20 per cent had completed primary school, 9 per cent had attended preparatory school, 5 per cent had attended secondary school, 1 per cent had had intermediate education, while 0.6 per cent had completed university or higher education. The results of this survey revealed that haemoglobinopathies are prevalent in Oman; the prevalence of sickle cell trait was 6 per cent, and of beta-thalassaemia 2 per cent. The prevalence of sickle cell and homozygous beta-thalassaemia were 0.2 and 0.07 per cent, respectively. Other abnormal haemoglobins (Hb) have been detected in this survey; HbD (0.6 per cent), HbE (0.3 per cent), HbC (0.02 per cent). Combination of sickle cell with other abnormal Hb was also detected at low prevalence. Glucose-6-phosphate dehydrogenase (G6PD) enzyme deficiency had a high prevalence in Oman, being 25 per cent in males and 10 per cent in females. Among the children studied, three-quarters (74.5 per cent) were found to be free from haemoglobinopathies and G6PD normal, the rest (25.5 per cent), either had haemoglobinopathies (7.5 per cent), G6PD deficiency (16 per cent) or a combination of G6PD deficiency with at least one abnormal Hb (2 per cent). The prevalence of total haemoglobinopathies in Oman was 9.5 per cent. The prevalence of sickle cell trait varied between regions, North Sharqiya had the highest prevalence of 10 per cent. Dakhiliya (9 per cent), followed by Muscat and South Batinah 8 and 7.9 per cent, respectively. The prevalence of sickle cell trait declined by a half in Musandam, South Sharqiya, Dhahira, and North Batinah (4.7, 3.9, 3.9, and 2.9 per cent respectively). Dhofar had the lowest prevalence of 0.2 per cent and no cases of sickle cell trait were found in the Al-Wousta region in the sample selected. The prevalence of beta-thalassaemia trait ranged from 3.9 to 0.2 per cent. Three regions had high rates: North Batinah (3.9 per cent), Muscat (2.8 per cent), and Dakhiliya (2 per cent). The other five regions in the Sultanate have lower rates: Dhahira (1.7 per cent), Musandam (1.6 per cent), South Batinah (1.5 per cent), South Sharqiya (1.2 per cent), and North Sharqiya (1.1 per cent). The prevalence of beta-thalassaemia trait in Dhofar was 0.2 per cent and no cases were detected in the Al-Wousta region. The prevalence of G6PD deficiency reached 29 per cent in Dakhiliya, 26 per cent in South Batinah, 21 per cent in Dhahira, 19 per cent in Muscat and 17 per cent in North Sharqiya and North Batinah. The prevalence declined to 10 per cent in Musandam, 9 per cent in South Sharqiya, Dhofar had the lowest prevalence of 2 per cent and no cases of G6PD deficiency were found in Al-Wousta. The male to female ratio was 2.5:1. In all regions of the Sultanate, prevalence of G6PD deficiency in males were more than twice those in females. From the above rates, it could be calculated that in the whole Sultanate 44,733 children under 5 years of age have G6PD deficiency, 14,306 have sickle cell trait, 474 have sickle cell disease, 5393 have beta-thalassaemia trait, and 175 have beta-thalassaemia major. The study showed that the mean Hb level of children under 5 years of age was 10.9 g/dl for both males and females; the mean Hb level for males was 10.89 g/dl and for females 10.99 g/dl, the difference between males and females was significant. The study revealed that half of the children under 5 years of age were anaemic. Mild anaemia was predominant (46 per cent), while moderate and severe anaemia were 4 and 0.2 per cent respectively. The status of anaemia among children improved with age; mild anaemia was prevalent in 65 per cent of children between ages 0 to < or = 1 years then decreased with age until it reached 30 per cent at 4-5 years of age. The survey produced the first normal haematological indices for children under 5 years of age to be used as a reference in the country. The blood picture of the normal subjects in the survey showed that the mean Hb value for males was 11.9 g/dl and for females 11.8 g/dl. The children had reduced values of MCH and MCV compared to normal international values, the reason for this could be alpha-thalassaemia or iron deficiency. The children maintained high values of HbF (more than 1.2 per cent) even after their first birthday. HbF reached its normal level at 5 years of age. Marriage of first cousins among the parents of the children studied under 5 years of age was 34 per cent. Total consanguinity rate including second cousin relationships and beyond was 58 per cent. We recommend that a national prevention programme for genetic blood disorders be formulated by the authorities. The programme could be included in the Ministry of Health 5-year health development programme for prevention of non-communicable diseases which already exists.