Presentation and Variability of APOL1-Related Kidney Disease

ABSTRACT

Inheritance of the APOL1 G1 or G2 risk alleles in the homozygous or compound heterozygous state, are associated with a ~7-30X increased risk of development of chronic kidney disease (CKD), and with collapsing glomerulopathies in individuals with viral infections including COVID-19 or HIV. Identification of APOL1 high risk genotypes (HRG) can impact patient treatment, prognosis and kidney donor selection. Approximately 13% of African Americans (AA) have an APOL1 HRG, indicating genetic testing in this population can identify those at-risk for CKD development, leading to appropriate patient counseling and management. Here we sought to understand the clinical presentation and variability among patients with APOL1 HRGs, following the implementation of genetic testing for kidney disease with a broad panel at a Louisiana Nephrology clinic. Clinical genetic testing of patient samples was performed using a >380 kidney gene panel (the RenasightTM test, Natera, Inc.) A retrospective review of clinical data for individuals positive for an APOL1 HRG (G1/G1, G2/G2, G1/G2) was performed. We identified 12 patients that were positive for an APOL1 HRG, with all genotypes represented G1/G1 (n=8), G1/G2 (n=3), and G2/G2 (n=1). Among this cohort, 100% (12/12) were of AA descent. At the time of testing 91% (11/12) of the patients were diagnosed with CKD or ESRD with proteinuria. Biopsy confirmed focal segmental glomerulosclerosis (FSGS) in two patients and collapsing glomerulopathy in one patient. The most common comorbidities among this cohort were hypertension (9/12) and diabetes mellitus (2/12). Four patients had a history of infection with COVID-19 (n=3) or HIV (n=1), three of whom had renal involvement (acute kidney injury or CKD and proteinuria). Use of a broad kidney gene panel enabled the identification of APOL1 HRGs in individuals for which hypertension or diabetes may have otherwise been attributed as the primary cause of CKD. APOL1 HRGs could also provide context for the renal involvement seen in the patients with COVID-19 or HIV infection. Broad panel genetic testing provides an accessible tool for nephrology clinics to help identify individuals at risk for positivity for an APOL1 HRG, including those of AA descent with hypertensive, proteinuric CKD.