Ethnicity and IgA nephropathy: worldwide differences in epidemiology, timing of diagnosis, clinical manifestations, management and prognosis

Abstract

Immunoglobulin A nephropathy (IgAN), the most common primary glomerulonephritis, is one of the major causes of end-stage renal disease. Significant variances in epidemiology, clinical manifestation, timing of diagnosis, management and renal prognosis of IgAN have been reported worldwide. The incidence of IgAN is the most frequent in Asia, followed by Europe, and lower in Africa. Moreover, Asian patients show more frequent acute lesions in renal histology and present poorer renal outcomes compared with Caucasians. The comorbidities also show the difference between Asians and Caucasians. Although the frequency of gross hematuria with upper respiratory tract infection is not different, comorbidities with gastrointestinal diseases are reported to be higher in Europe. Recently, genetic studies for variant ethnic patients revealed widely ranging genetic risks in each ethnicity. A genetic risk score is most elevated in Asians, intermediate in Europeans and lowest in Africans, consistent with the disease prevalence of IgAN globally. Ethnic variance might be highly affected by the difference in genetic background. However, it is also essential to mention that the different timing of diagnosis due to variant urinary screening systems and the indication for renal biopsy in different countries may also contribute to these variances. The management of IgAN also varies internationally. Currently, several novel therapies based on the pathogenesis of IgAN are being assessed and are expected to become available soon. Further understanding the ethnic variance of IgAN might help establish individualized care for this disease. Here, we review the issues of ethnic heterogeneities of IgAN.

IGA‐Nephropathy in Northeastern Europe: Clinical and Morphological Presentation and Outcomes

“…Indeed, we demonstrated that IgAN was the most frequent variant of immune glomerulopathies and the most prevalent kidney disease by clinical and morphologic examination in this region. Moreover, the prevalence of IgAN in NEE seems to be ahead of most regions in Europe and America and comparable to Asian countries [1,16,[21][22][23]25,26].…”

“…The disease is most prevalent in people of East Asia ancestry (45-58% of primary glomerulonephritis), followed by Caucasians and relatively rare in individuals of African descent. It has been estimated to account for approximately 40% of all native biopsies in Japan, 25% in Europe, 12% in the USA and less than 5% in Central Africa [1,[21][22][23][24].…”

Mortality in IgA Nephropathy: A Long-Term Follow-Up of an Eastern European Cohort

“…Few studies specifically focus on mortality as a separate endpoint in IgAN (Table 3), often combining it with ESKD in a composite endpoint and not detailing each event individually [32,33]. Addressing vital survival separately is crucial, particularly given IgAN's impact on a younger demographic and its significant social and economic effects [34]. Additionally, survival may vary based on a country's healthcare policies, with active screening in Asian populations showing improved outcomes [34].…”

“…Addressing vital survival separately is crucial, particularly given IgAN's impact on a younger demographic and its significant social and economic effects [34]. Additionally, survival may vary based on a country's healthcare policies, with active screening in Asian populations showing improved outcomes [34]. Understanding regional variations in IgAN patient survival is essential, especially with the development of various treatment classes in advanced trials.…”

Advancements in understanding the role of intestinal dysbacteriosis mediated mucosal immunity in IgA nephropathy

“…Subsequent clinical observations have shown that many IgAN patients experience worsening of their condition, with the appearance of gross hematuria, following upper respiratory tract infections such as tonsillitis. This suggests that the tonsils and upper respiratory mucosal immunity may play a role in the pathogenesis of IgAN [ 60 – 62 ]. This has led to increased interest in studying the role of the tonsils and their associated mucosal immunity in IgAN pathogenesis.…”