A Comparative Genetic-Epidemiological Study of Some lIuman Disease Traits and ABO Blood Groups among Different Population Categories in Harari Region of Ethiopia

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Addis Ababa University


A comparative Genetic-Epidemiological analysis was carried out in HarGl'i Region of Ethiopia (Region-I3) on the spectl1lm, ji-equency, and distribution of some selected human traits which have been described by several previous scientific investigations as being genetically determined: (I) Genetic diseases which arefolllld under various disease classification categories of the Ethiopian Minisfly of Health's "List of Causes for Tabulation of Morbidity and Mortality" and (2) the ABO blood groups. From all available medical data of IO-years (I984-I994 E.C.), a total sample of more thanI2,OOO cases of the various selected disease conditions were collected ji-om hospital inpatient belonging to different Population Categories (PCs) characterized by different 'Local Ethno-Geographic' backgrounds; and 279 blood samples were taken ji-Olll informed volunteers of the normal population with different ethnic origins-Oromo, Amhara, alld HarGl·i. The genetic disease samples collected ji'Oln hospital records of inpatient populations were grouped into four basic PCs that closely follow or approximate their historical settlement patterns as well as current administrative boundaries of HarGl'i Region, which are both presumed to be based upon and reflect the ethnic identities or composition of their respective inhabitants; the blood samples were grouped into three groups based 011 the ethnic origin of the volunteers. (1) The statistical analysis results with regard to the RFD of disease traits were found to be age and sex specific among the compared PC pairs. PC-I was found to be the most distinctive population categOlY of all in its RFD of those disease traits classified under Dxgroup- 2 (Neoplasms), Dxgroup-3 (Deficiency Diseases- Diabetes Mellitus and Diabetes Insipidus), and Dxgroup-6 (Diseases of the Nervous System and Sense Organs- Epilepsy, Cataract, and Glaucoma). PC-I showed no significant variation ji-om any of the other PCs ill its RFD of Dxgroup-I (Malaria), Dxgroup-9 (Diseases of the Digestive System), Dxgroup-IO (Diseases of the Genito-UrillGlY System), and Dxgroup-II (Diseases Associated with Pregnancy, Child Birth, and the Puelperium). (ll) The statistical tests concerning the ABO blood group samples obtained ji'Oln the three major ethnic groups in HarGl'i Regioll showed that (1) Phenotypic heterogeneity test: the total chi-square values for homogeneity were nOll-significant both among the (i) Oromo, Amhara, and HarGl'i entries, and (ii) Oromo and Amhara entries with Chi-square=5.932, df=6, p>O.05 and Chi-square=4.332, df= 3, p>O.05, respectively, indicating phenotypic homogeneity. (Similar tests on the other possible data combinations could not be pelformed due to insufficient data.) (2) Genetic-equilibriulll test: (i) the Chi-square values for genetic equilibrium were nonsignificant for both the Drama and Amhara entries indicating random intra-ethnic mating to the extent of reaching genetic equilibrium, (Similar tests on the Harm'i enl1y could not be pe/formed due to insufficient data.) (ii) the total Chi-square values for genetic equilibriulll were IlOnsignificant for the combined entries of the Drama, Amhara, and Harm'i as well as the combined entries of the Drama and Amhara indicating either that (a) there is random inter-ethnic mating between the populations ji'om which the samples were taken, or (b) the samples were taken ji'01l! different ethnic populations each of which are randomly mating within themselves and are all at genetiC equilibrium as well as possessing similar proportions of the alleles at the ABO locus, (iii) the total Chi-square vailles for genetic equilibrium were significant for the combined entries of the Drama and Harm'i as well as the combined entries of the Amhara and Harm'i indicating that the Harm'i do not engage in random inter-ethnic reproductive mixing with neither the Amhara nor the Drama, although they are genetically closer to the later than the former ethnic group,