Genome-wide association studies have previously shown a strong signal between a region residing on chromosome 22 centered on MYH9 and African Americans with FSGS and hypertension attributed end-stage kidney disease (H-ESKD). On July 15, 2010, Science released online a publication revealing a strong association between the same but expanded interval containing a nearby gene encoding for apolipoprotein L-1 (APOL1) in a similar group of patients.

The investigators, led by Dr. Martin Pollak, the chief of the Division of Nephrology at Boston's Beth Israel Deaconess Medical Center, reasoned that because no causal mutations have been identified in MYH9, other alleles ought to be considered. Furthermore, recent selection pressures in Africans could lead to longer patterns of linkage disequilibrium (LD). More, but previously unavailable, data from African individuals whose DNA were sequenced in the 1000 Genomes Project (www.1000genomes.org) was used to identify polymorphisms that showed large frequency differences between Africans and Europeans.

An initial association analysis was done comparing 205 African-American sporadic cases with biopsy proven FSGS to 180 African-American controls. The strongest signals were found in the last exon of APOL1. More specifically, two closely spaced alleles that are in perfect LD (i.e. no recombination events) showed the strongest association. This two-allele haplotype termed “G1” consisted of the non-synonymous coding variants rs73885319 (S342G) and rs60910145 (I384M). Logistic regression analysis to control for G1 led to the identification of a second strong association with a 6 base pair deletion in APOL1 termed G2.

Many nephrologists, myself included, are eager to find alternatives to cyclophosphamide in the management of lupus nephritis. As many of these patients are young men and women of child-bearing age, the effects of cyclophosphamide on fertility, along with bone marrow and other adverse effects make alternative medications more attractive. Several studies have suggested that mycophenolate mofetil (MMF) may be superior and less toxic than cyclophosphamide in the management of lupus nephritis. In the May issue of the Journal of the American Society of Nephrology, investigators report the result of a study comparing IV cyclophsphamide with oral MMF. While a reprint is not yet available for review, preliminary reports suggest that MMF is slightly more effective and less toxic in this trial. In a 24-week open-label induction study of 370 patients with class III-V lupus, there were no differences in the primary end-point (a prespecified decrease in urine protein/creatinine ratio and stabilization or improvement in serum creatinine) or the secondary end-point (complete renal remission, systemic disease activity and damage, and safety).  As well, there were no differences in the rate of adverse events between the 2 groups. For the studied patients, IV cyclophosphamide and oral MMF share similar efficacy and harm. This study adds to the growing evidence base showing no difference between these 2 treatment strategies.

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