title: High population frequencies of APOL1 risk variants are associated with increased prevalence of non-diabetic chronic kidney disease in the Igbo people from south-eastern Nigeria.
abstract: BACKGROUND
  Continental Africa is facing an epidemic of chronic kidney disease (CKD). APOL1 risk variants have been shown to be strongly associated with an increased risk for non-diabetic kidney disease including HIV nephropathy, primary non-monogenic focal and segmental glomerulosclerosis, and hypertension-attributed nephropathy among African ancestry populations in the USA. The world's highest frequencies of APOL1 risk alleles have been reported in West African nations, overlapping regions with a high incidence of CKD and hypertension. One such region is south-eastern Nigeria, and therefore we sought to quantify the association of APOL1 risk alleles with CKD in this region.
  
  
  METHODS
  APOL1 risk variants were genotyped in a case-control sample set consisting of non-diabetic, CKD patients (n = 44) and control individuals (n = 43) from Enugu and Abakaliki, Nigeria.
  
  
  RESULTS
  We found a high frequency of two APOL1 risk alleles in the general population of Igbo people of south-eastern Nigeria (23.3%). The two APOL1 risk allele frequency in the CKD patient group was 66%. Logistic regression analysis under a recessive inheritance model showed a strong and significant association of APOL1 two-risk alleles with CKD, yielding an odds ratio of 6.4 (unadjusted p = 1.2E-4); following correction for age, gender, HIV and BMI, the odds ratio was 4.8 (adjusted p = 5.1E-03).
  
  
  CONCLUSIONS
  APOL1 risk variants are common in the Igbo population of south-eastern Nigeria, and are also highly associated with non-diabetic CKD in this area. APOL1 may explain the increased prevalence of CKD in this region.
authors.affiliation: Renal Unit, Department of Medicine, College of Medicine, Enugu Campus, Enugu, Nigeria.
authors.forename: Ifeoma I
authors.initials: II
authors.lastname: Ulasi
authors.forename: Shay
authors.initials: S
authors.lastname: Tzur
authors.forename: Walter G
authors.initials: WG
authors.lastname: Wasser
authors.forename: Revital
authors.initials: R
authors.lastname: Shemer
authors.forename: Etty
authors.initials: E
authors.lastname: Kruzel
authors.forename: Elena
authors.initials: E
authors.lastname: Feigin
authors.forename: Chinwuba K
authors.initials: CK
authors.lastname: Ijoma
authors.forename: Obinna D
authors.initials: OD
authors.lastname: Onodugo
authors.forename: Julius U
authors.initials: JU
authors.lastname: Okoye
authors.forename: Ejikeme B
authors.initials: EB
authors.lastname: Arodiwe
authors.forename: Ngozi A
authors.initials: NA
authors.lastname: Ifebunandu
authors.forename: Chinwe J
authors.initials: CJ
authors.lastname: Chukwuka
authors.forename: Cajetan C
authors.initials: CC
authors.lastname: Onyedum
authors.forename: Uchenna N
authors.initials: UN
authors.lastname: Ijoma
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Nna
authors.forename: Macaulay
authors.initials: M
authors.lastname: Onuigbo
authors.forename: Saharon
authors.initials: S
authors.lastname: Rosset
authors.forename: Karl
authors.initials: K
authors.lastname: Skorecki
mesh_terms: D000328:Adult; D000075944:Apolipoprotein L1; D001053:Apolipoproteins / Q000235:genetics*; D003920:Diabetes Mellitus / Q000208:ethnology / Q000235:genetics; D005260:Female; D005819:Genetic Markers / Q000235:genetics; D020022:Genetic Predisposition to Disease / Q000453:epidemiology* / Q000235:genetics*; D014644:Genetic Variation / Q000235:genetics*; D006801:Humans; D008075:Lipoproteins, HDL / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009549:Nigeria / Q000453:epidemiology; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D015995:Prevalence; D051436:Renal Insufficiency, Chronic / Q000208:ethnology* / Q000235:genetics*; D012307:Risk Factors
chemical_list: C108666:APOL1 protein, human; D000075944:Apolipoprotein L1; D001053:Apolipoproteins; D005819:Genetic Markers; D008075:Lipoproteins, HDL