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Epidemiological studies on racial/ethnic and geographical distribution of IgA nephropathy (IgAN) have been limited by the lack of studies from Africa. Despite IgAN being the leading primary glomerulonephritis worldwide, reports in the published literature suggest that it is rarely observed among ethnic Africans (black Africans) and those of African ethnic descent including African Americans. This contrasts with the high prevalence of IgAN among those of Asian and Caucasian ethnic decent. Whereas it has been postulated that the rarity of IgAN among ethnic Africans could be related to genetics and/or various environmental factors, some researchers have posited that it could be related to the low rate of renal biopsy in Africa. In fact, besides a few reports from South Africa, there are no Africa-based studies from Sub-Saharan Africa detailing the prevalence of IgAN in the Sub-Saharan African setting, and this has been stated to be due to the low renal biopsy rates and lack of immunohistochemical diagnostic capacity which are requisite for the diagnosis of IgAN. To the best of our knowledge there have not been any published data on IgAN in East Africa. This report seeks to address the knowledge gap on IgAN in Sub-Saharan Africa through sharing of data on IgAN from a referral pathology laboratory in East Africa.
This is a cross-sectional retrospective analysis of data extracted from histopathology reports of renal biopsies over a 10-year period between 2011 and 2020 at a central referral independent pathology laboratory in Kenya serving public and private sector patients. The laboratory has the largest database of renal biopsies in that period including immunohistochemistry results. Cases of IgAN were searched in text form using the key words “IgAN” and the respective cases identified were further examined in the pathology report to confirm those that were diagnosed as IgAN by the reporting pathologist based on immunohistochemistry results and clinicopathological correlation. The race/ethnicity of the patients were inferred from the names of the patients and counterchecked with the referring clinicians. The results were tabulated and tallied on Excel spreadsheet to obtain the summary statistics.
During the 10-year period under review there were 1413 renal biopsies that had full pathology reporting, of which 1304 (92.3%) were native kidney biopsies while 109 (7.7%) were transplant biopsies. Out of these, there were eleven (11) cases of confirmed IgAN of which one (1) was in a transplant kidney biopsy. Of the confirmed cases of IgAN, 45% (6) of the total were among black ethnic Africans while 55% were among patients who were Asian (5) and Caucasian (1). Several other cases of presumptive Ig nephropathy were also on record which on clinicopathological correlation turned out to be IgA predominant lupus nephritis (6 cases) or Henoch-Schonlein Purpura (3) or IgA predominant acute post-infectious glomerulonephritis (1). The male to female ratio for the IgAN patients was 4:1 among the ethnic Africans, and 2:1 among the others. The average age for the cohort was 33 years with a median age of 32 years. Overall, IgAN comprised only 0.8% of all the pathology biopsy reports over the 10-year period.
This case series of IgAN from one of the busiest pathology referral laboratories in East Africa handling renal biopsies from public and private sector patients further adds to the body of evidence that IgAN is rare in Africa and among those of ethnic (black) African descent. This rarity of IgAN appears not to be related to biopsy rates as it contrasts to the large number of other glomerulonephritides recorded in this period FSGS, membranous nephropathy, minimal change disease, MPGN and lupus nephritis as the commonest glomerular diseases seen on renal biopsies in this setting. The pathogenesis of IgAN remains elusive but its rarity among ethnic Africans within Africa and those of ethnic African descent living in other environments outside Africa suggests that there are possible genetic and related factors that make IgA much less common among ethnic Africans compared to Asians and Caucasians amongst whom IgAN remains the most common primary glomerulonephritis worldwide. More studies are needed of IgAN amongst ethnic Africans in the African setting to better elucidate the etiopathological factors behind the huge geographical and racial/ethnic disparity in Africa.