|Abstract:||A comparative Genetic-Epidemiological analysis uws carried out in Harari Region of Ethiopia (Region-13) on the spectrum, frequency, and distribution of some selected human traits which have been described by several previous scientific investigations as being genetically determined: (1) Genetic diseases which are found under various disease classification categories of the Ethiopian Ministry of Health’s “ List of Causes for Tabulation of Morbidity and Mortality’’ and (2) the ABO blood groups. From all available medical data of 10-years (1984-1994 E.C.), a total sample of more than 12,000 cases of the various selected disease conditions were collected from hospital inpatient belonging to different Population Categories (PCs) characterized by different ‘Local Ethno-Geographic’ backgrounds; and 279 blood samples were taken from informed volunteers of the normal population with different ethnic origins-Oromo, Amhara, and Harari. The genetic disease samples collected from 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 Harari 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 on 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-1 was found to be the most distinctive population categoiy 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-1 showed no significant variation from any of the other PCs in its RFD of: Dxgroup-1 (Malaria), Dxgroup-9 (Diseases of the Digestive System), Dxgroup-10 (Diseases of the Genito-Urmaiy System), and Dxgroup-11 (Diseases Associated with Pregnancy, Child Birth, and the Puerperium). (II) The statistical tests concerning the ABO blood group samples obtained from the three major ethnic groups in Harari Region showed that (1) Phenotypic heterogeneity test: the total chi-square values for homogeneity were nonsignificant both among the (i) Oromo, Amhara, and Harari entries, and (ii) Oromo and Amhara entries with Chi-square=5.932, df-6, p>0.05 and Chi-square=4.332, df= 3, p>0.05, respectively, indicating phenotypic homogeneity. (Similar tests on the other possible data combinations could not be performed due to insufficient 5data.) (2) Genetic-equilibrium test: (i) the Chi-square values for genetic equilibrium were nonsignificant for both the Ororno and Amhara entries indicating random intra-ethnic mating to the extent of reaching genetic equilibrium. (Similar tests on the Harari entiy could not be performed due to insufficient data.) (ii) the total Chi-square values for genetic equilibrium were nonsignificant for the combined entries of the Ororno, Amhara, and Harari as well as the combined entries of the Ororno and Amhara indicating either that (a) there is random inter-ethnic mating between the populations from which the samples were taken, or (b) the samples were taken from 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. (Hi) the total Chi-square values for genetic equilibrium were significant for the combined entries of the Ororno and Harari as well as the combined entries of the Amhara and Harari indicating that the Harari do not engage in random inter-ethnic reproductive mixing with neither the Amhara nor the Ororno, although they are genetically closer to the later than the former ethnic group.|