Ethnic distribution of Haemoglobinopathies Gene in Tribes of Northern Darfur State - Sudan

Abstract

The study is a community based study that aimed to determine the prevalence of haemoglopinopathies. It conducted in Northern Darfur State tribes, during the period from July 2012 to August 2015. Following informed consent, a total of six hundred and sixty six individuals enrolled in the study, with mean age 21.7 ± 18.3 years for female and 20.9 ± 15.4 years for males. There were 369 (55%) females and 297 (45%) males. Most of the Northern Darfur tribes were included; the highest frequency was among Fur and Zagawa tribes. 5 mls venous blood samples were collected from each individual, Blood sample was collected in EDTA containers. In each specimen two tests were performed complete blood count and capillary zone electrophoresis and then haplotypes for the HbSS samples. The results of mean hematological parameters was found within the normal range, the mean haemoglobin concentration was 12.6±2.19 g/dl, PCV 38.5%, RBCs count 4.7±0.8×1012/L, MCV 84.9 fl, MCH 27.9 pg, MCHC 32.8 g, TWBCs 6.9±2.2×10³/µL and the mean Plts count was 265±×8410³/µL. While the mean Hb in AS individuals was 11.8 g/dl, in Hb SS individuals 6.95 g/dl and in Hb AD individuals was 12.4 g/dl. Four variants of Hb were detected; these were Hb AA (86.94), Hb AS (10.51%), Hb SS (1. 95%) and Hb AD (0.6%). Hb AA (adult Hb or normal Hb) was predominant. Hb AS and Hb SS had a higher frequency than other abnormal Hb. The homozygous form of HbSS was found in four tribes, with higher frequency in Housa tribe 10.26 % and lower frequency in Zagawa tribe 1.74%. While the heterozygous form (HbAS) was found in many tribes of Northern Darfur state, the high frequency was in Keneen tribe 30.7% and the lower frequency in the Tongour tribe 5.4%. In contrast, HbS was not found in other tribes. The heterozygous form HbAD (a new Hb variant was apparent in Northern Darfur, in addition to the known abnormal Hb), was found only in four ethnic groups of Northern Darfur, Gemer, Ziadya, Bartey and Zagawa tribes at 33.3%, 4.2%, 1.4 and 0.8% respectively. Haplotypes could be assigned unequivocally to thirteen patients; four of the five typical βs globin haplotypes were identified. The most frequent was the Cameroon (84.6%) followed by the Benin (53.8%), the Bantu (46.2%) and the Senegal (15.4%). The Indian – Arab haplotypes was not detected. In conclusion, the mean hematological parameters were found within normal range among the study population, and the prevalence of haemoglopinopathies in this study was 13.06%, with Hb S most common among patients with abnormal Hb. A new Hb variant is apparent in Northern Darfur (Hb AD). Four African haplotypes were identified.