Exome wide association study on Albuminuria identifies a novel rare variant inCUBNand additional genes, in 33985 Europeans with and without diabetes
Authors: Ahluwalia Tarunveer S. , Schulz Christina-Alexendra , Waage Johannes , Skaaby Tea , Sandholm Niina , van Zuydam Natalie , Charmet Romain , Bork-Jensen Jette , Almgren Peter , Thuesen Betina H. , Bedin Mathilda , Brandslund Ivans , Chrisitansen Cramer K. , Linneberg Allan , Ahlqvist Emma , Groop Per-Henrik , Hadjadj Samy , Tregouet David-Alexandre , Jørgensen Marit E. , Grarup Niels , Simons Matias , Groop Leif , Melander Marju-Orho , McCarthy Mark , Melander Olle , Rossing Peter , Kilpelainen Tuomas O. , Hansen Torben 
Published: June 2018

Identifying rare coding variants associated with albuminuria may open new avenues for preventing chronic kidney disease (CKD) and end-stage renal disease which are highly prevalent in patients with diabetes. Efforts to identify genetic susceptibility variants for albuminuria have so far been limited with the majority of studies focusing on common variants.

We performed an exome-wide association study to identify coding variants in a two phase (discovery and replication) approach, totaling to 33,985 individuals of European ancestry (15,872 with and 18,113 without diabetes) and further testing in Greenlanders (n = 2,605). We identify a rare (MAF: 0.8%) missense (A1690V) variant inCUBN(rs141640975, β=0.27, p=1.3 × 10−11) associated with albuminuria as a continuous measure in the combined European meta-analyses. Presence of each rare allele of the variant was associated with a 6.4% increase in albuminuria. The rareCUBNvariant had 3 times stronger effect in individuals with diabetes compared to those without(pinteraction:5.4 × 10−4, βDM: 0.69, βnonDM:0.20) in the discovery meta-analyses. Geneaggregate tests based on rare and common variants identify three additional genes associated with albuminuria(HES1, CDC73, andGRM5)after multiple testing correction (P_bonferroni<2.7 × 10−6).

The current study identifies a rare coding variant in theCUBNlocus and other potential genes associated with albuminuria in individuals with and without diabetes. These genes have been implicated in renal and cardiovascular dysfunction. These findings provide new insights into the genetic architecture of albuminuria and highlight novel target genes and pathways for prevention of diabetes-related kidney disease.

Significance statement

Increased albuminuria is a key manifestation of major health burdens, including chronic kidney disease and/or cardiovascular disease. Although being partially heritable, there is a lack of knowledge on rare genetic variants that contribute to albuminuria. The current study describes the discovery and validation, of a new rare gene mutation (~1%) in theCUBNgene which associates with increased albuminuria. Its effect multiplies 3 folds among diabetes cases compared to non diabetic individuals. The study further uncovers 3 additional genes modulating albuminuria levels in humans. Thus the current study findings provide new insights into the genetic architecture of albuminuria and highlight novel genes/pathways for prevention of diabetes related kidney disease.