Familial clustering of ESRD in the Norwegian population

Causes and timing of end-stage renal disease after living kidney donation

End-stage renal disease (ESRD) is a risk after kidney donation. We sought, in a large cohort of kidney donors, to determine the causes of donor ESRD, the interval from donation to ESRD, the role of the donor/recipient relationship, and the trajectory of the estimated GFR (eGFR) from donation to ESRD. From 1/1/1963 thru 12/31/2015, 4030 individuals underwent living donor nephrectomy at our center, as well as ascertainment of ESRD status. Of these, 39 developed ESRD (mean age ± standard deviation [SD] at ESRD, 62.4 ± 14.1 years; mean interval between donation and ESRD, 27.1 ± 9.8 years). Donors developing ESRD were more likely to be male, as well as smokers, and younger at donation, and to have donated to a first-degree relative. Of donors with a known cause of ESRD (n = 25), 48% was due to diabetes and/or hypertension; only 2 from a disease that would have affected 1 kidney (cancer). Of those 25 with an ascertainable ESRD cause, 4 shared a similar etiology of ESRD with their recipient. Almost universally, thechange of eGFR over time was stable, until new-onset disease (kidney or systemic). Knowledge of factors contributing to ESRD after living kidney donation can improve donor selection and counseling, as well as long-term postdonation care.

Risk of ESRD in prior living kidney donors

We studied End-Stage Renal Disease (ESRD) in living kidney donors (LKDs) who donated in the United States between 1994 and 2016 (n = 123 526), using Organ Procurement and Transplantation Network and Centers for Medicare and Medicaid Services data. Two hundred eighteen LKDs developed ESRD, with a median of 11.1 years between donation and ESRD. Absolute 20-year risk was low but not uniform, with risk associated with race, age, and sex and increasing exponentially over time. LKDs had increased risk of ESRD if they were male (adjusted hazard ratio [aHR]: 1.75, 95% confidence interval [95%CI]: 1.33-2.31), had higher BMI (aHR: 1.34 per 5 kg/m² , 95%CI: 1.10-1.64) or lower estimated GFR (aHR: 0.89 per 10 mL/min, 95% CI: 0.80-0.99), were first-degree relatives of the recipient (parent: [aHR: 2.01, 95% CI: 1.26-3.21]; full sibling [aHR: 1.87, 95%CI: 1.23-2.84]; identical twin [aHR: 19.79, 95%CI: 7.65-51.24]), or lived in lower socioeconomic status neighborhoods at donation (aHR: 0.87 per $10k increase; 95%CI: 0.77-0.99). We found a significant interaction between donation age and race, with higher risk at older ages for white LKDs (aHR: 1.26 per decade, 95%CI: 1.04-1.54), but higher risk at younger ages for black LKDs (aHR: 0.75 per decade, 95%CI: 0.57-0.99). These findings further inform risk assessment of potential LKDs.

Long-term risks of kidney living donation: review and position paper by the ERA-EDTA DESCARTES working group

Two recent matched cohort studies from the USA and Norway published in 2014 have raised some concerns related to the long-term safety of kidney living donation. Further studies on the long-term risks of living donation have since been published. In this position paper, Developing Education Science and Care for Renal Transplantation in European States (DESCARTES) board members critically review the literature in an effort to summarize the current knowledge concerning long-term risks of kidney living donation to help physicians for decision-making purposes and for providing information to the prospective live donors. Long-term risk of end-stage renal disease (ESRD) can be partially foreseen by trying to identify donors at risk of developing ‘de novo’ kidney diseases during life post-donation and by predicting lifetime ESRD risk. However, lifetime risk may be difficult to assess in young donors, especially in those having first-degree relatives with ESRD. The study from Norway also found an increased risk of death after living donor nephrectomy, which became visible only after >15 years of post-donation follow-up. However, these findings are likely to be largely the result of an overestimation due to the confounding effect related to a family history of renal disease. DESCARTES board members emphasize the importance of optimal risk–benefit assessment and proper information to the prospective donor, which should also include recommendations on health-promoting behaviour post-donation.

GFR ≤25 years postdonation in living kidney donors with (vs. without) a first-degree relative with ESRD

An increased risk of ESRD has been reported for living kidney donors, and appears to be higher for those donating to a relative. The reasons for this are not clear. One possibility is that ESRD is due to the nephrectomy-related reduction in GFR, followed by an age-related decline that may be more rapid in related donors. Between 1/1/1990 and 12/31/2014, we did 2002 living donor nephrectomies. We compared long-term postdonation eGFR trajectory for donors with (n = 1245) vs. without (n = 757) a first-degree relative with ESRD. Linear mixed-effects models were used to model the longitudinal trajectory of eGFR. With all other variables held constant, we noted a steady average increase in eGFR until donors reached age 70: 1.12 (95% CI: 0.92-1.32) mL/min/1.73m^² /yr between 6 weeks and 5 years postdonation; 0.24 (0.00-0.49) mL/min/1.73m^² /yr between 5 and 10 years; and 0.07 (-0.10 to +0.25) mL/min/1.73m^² /yr between 10 and 20 years for donors with attained age less than 70. After age 70, eGFR declined. After we adjusted for predonation factors, the difference in eGFR slopes between related and unrelated donors was 0.20 mL/min/1.753 m² /year (0.07-0.33). Our data suggests that postdonation, kidney donor eGFR increases each year for a number of years and that eGFR trajectory does not explain any increase in ESRD after donation.

Genomic medicine for kidney disease

Technologies such as next-generation sequencing and chromosomal microarray have advanced the understanding of the molecular pathogenesis of a variety of renal disorders. Genetic findings are increasingly used to inform the clinical management of many nephropathies, enabling targeted disease surveillance, choice of therapy, and family counselling. Genetic analysis has excellent diagnostic utility in paediatric nephrology, as illustrated by sequencing studies of patients with congenital anomalies of the kidney and urinary tract and steroid-resistant nephrotic syndrome. Although additional investigation is needed, pilot studies suggest that genetic testing can also provide similar diagnostic insight among adult patients. Reaching a genetic diagnosis first involves choosing the appropriate testing modality, as guided by the clinical presentation of the patient and the number of potential genes associated with the suspected nephropathy. Genome-wide sequencing increases diagnostic sensitivity relative to targeted panels, but holds the challenges of identifying causal variants in the vast amount of data generated and interpreting secondary findings. In order to realize the promise of genomic medicine for kidney disease, many technical, logistical, and ethical questions that accompany the implementation of genetic testing in nephrology must be addressed. The creation of evidence-based guidelines for the utilization and implementation of genetic testing in nephrology will help to translate genetic knowledge into improved clinical outcomes for patients with kidney disease.

Whole-Exome Sequencing in Adults With Chronic Kidney Disease: A Pilot Study

BACKGROUND

The utility of whole-exome sequencing (WES) for the diagnosis and management of adult-onset constitutional disorders has not been adequately studied. Genetic diagnostics may be advantageous in adults with chronic kidney disease (CKD), in whom the cause of kidney failure often remains unknown.

OBJECTIVE

To study the diagnostic utility of WES in a selected referral population of adults with CKD.

DESIGN

Observational cohort.

SETTING

A major academic medical center.

PATIENTS

92 adults with CKD of unknown cause or familial nephropathy or hypertension.

MEASUREMENTS

The diagnostic yield of WES and its potential effect on clinical management.

RESULTS

Whole-exome sequencing provided a diagnosis in 22 of 92 patients (24%), including 9 probands with CKD of unknown cause and encompassing 13 distinct genetic disorders. Among these, loss-of-function mutations were identified in PARN in 2 probands with tubulointerstitial fibrosis. PARN mutations have been implicated in a short telomere syndrome characterized by lung, bone marrow, and liver fibrosis; these findings extend the phenotype of PARN mutations to renal fibrosis. In addition, review of the American College of Medical Genetics actionable genes identified a pathogenic BRCA2 mutation in a proband who was diagnosed with breast cancer on follow-up. The results affected clinical management in most identified cases, including initiation of targeted surveillance, familial screening to guide donor selection for transplantation, and changes in therapy.

LIMITATION

The small sample size and recruitment at a tertiary care academic center limit generalizability of findings among the broader CKD population.

CONCLUSION

Whole-exome sequencing identified diagnostic mutations in a substantial number of adults with CKD of many causes. Further study of the utility of WES in the evaluation and care of patients with CKD in additional settings is warranted.

PRIMARY FUNDING SOURCE

New York State Empire Clinical Research Investigator Program, Renal Research Institute, and National Human Genome Research Institute of the National Institutes of Health.

Association of EPHX2 R287Q Polymorphism with Diabetic Nephropathy in Chinese Type 2 Diabetic Patients

The aim of this study was to investigate the relationship between EPHX2 rs751141 (R287Q polymorphism) and diabetic nephropathy (DN) in Chinese type 2 diabetes (T2D). This case-control study explored the association between EPHX2 rs751141 and DN in a total of 870 Chinese T2D patients (406 T2D patients with DN and 464 T2D patients without DN). DNA was extracted from peripheral leukocytes of the patients and rs751141 was genotyped. The A allele frequency of rs751141 was significantly lower in DN patients (20.94%) compared with non-DN controls (27.8%) (P = 0.001), and the A allele of rs751141 was associated with a significantly lower risk of DN after adjustment for multiple covariates in the additive genetic model (OR = 0.68, 95% CI = 0.52-0.88, P = 0.004). Significant association between rs751141 and homocysteine (Hcy) level on the risk of DN was observed, indicating that in patients with the highest Hcy levels, the A allele showed marked association with lower risk of DN in all three genetic models. In conclusion, the A allele of exonic polymorphism in EPHX2 rs751141 is negatively associated with the incidence of DN in the Chinese T2D population, which could be modulated by Hcy level status.

Heritability of End-Stage Renal Disease: A Swedish Adoption Study

BACKGROUND/AIMS

The heritability of end-stage renal disease (ESRD) among adoptees has not been examined so far. By studying adoptees and their biological and adoptive parents, it is possible to differentiate between the genetic causes and environmental causes of familial aggregation. This nationwide study aimed to disentangle the genetic and shared environmental contribution to the familial transmission of ESRD.

METHODS

We performed a family study for Swedish-born adoptees (born between 1945 until 1995) and their biological and adoptive parents. The Swedish Multi-Generation Register was linked to the National Patient Registry for the period 1964-2012. ESRD was defined as patients in active uremic care, that is, chronic dialysis or kidney transplantation. OR for ESRD was determined for adoptees with an affected biological parent with ESRD compared with adoptees without a biological parent with ESRD. The OR for ESRD was also calculated in adoptees with an adoptive parent with ESRD compared with adoptees with an adoptive parent without ESRD. Moreover, heritability for ESRD was estimated with Falconer's regression.

RESULTS

A total of 111 adoptees, 463 adoptive parents, and 397 biological parents were affected by ESRD. The OR for ESRD was 6.41 in adoptees (95% CI 2.96-13.89) of biological parents diagnosed with ESRD. The OR for ESRD was 2.40 in adoptees (95% CI 0.76-7.60) of adoptive parents diagnosed with ESRD. The heritability of ESRD was 59.5 ± 18.2%.

CONCLUSION

The family history of ESRD in a biological parent is an important risk factor for ESRD. The high heritability indicates that genetic factors play an important role in understanding the etiology of ESRD.

Epigenome-wide association studies identify DNA methylation associated with kidney function

Chronic kidney disease (CKD) is defined by reduced estimated glomerular filtration rate (eGFR). Previous genetic studies have implicated regulatory mechanisms contributing to CKD. Here we present epigenome-wide association studies of eGFR and CKD using whole-blood DNA methylation of 2264 ARIC Study and 2595 Framingham Heart Study participants to identify epigenetic signatures of kidney function. Of 19 CpG sites significantly associated (P < 1e-07) with eGFR/CKD and replicated, five also associate with renal fibrosis in biopsies from CKD patients and show concordant DNA methylation changes in kidney cortex. Lead CpGs at PTPN6/PHB2, ANKRD11, and TNRC18 map to active enhancers in kidney cortex. At PTPN6/PHB2 cg19942083, methylation in kidney cortex associates with lower renal PTPN6 expression, higher eGFR, and less renal fibrosis. The regions containing the 243 eGFR-associated (P < 1e-05) CpGs are significantly enriched for transcription factor binding sites of EBF1, EP300, and CEBPB (P < 5e-6). Our findings highlight kidney function associated epigenetic variation.

Genome-wide association studies of kidney function show enrichment of associated genetic variants in regulatory regions. Here, the authors perform epigenome-wide association studies of kidney function and disease, identifying 19 CpG sites significantly associated with these.

Risk of infectious diseases among first-degree relatives of transplant recipients who develop CMV infection: is the infectious phenotype inheritable?

Transplant recipients are at high risk of cytomegalovirus (CMV) infection. Mechanisms explaining the variation in risk of infections are far from fully elucidated. We hypothesised that host genetics explains part of the variation in risk of infection and examined if relatives of recipients with CMV infection have higher rates of severe infections compared to relatives of recipients without this infectious phenotype. In a register-based study, we included first-degree relatives of transplant recipients and examined the risk of hospitalisation due to overall infection or viral infection and risk of death among relatives of recipients who developed CMV infection within the first year of transplantation compared to relatives of recipients without CMV. Analyses were adjusted for sex, age and calendar year. We included 4470 relatives who were followed for 103,786 person-years, median follow-up 24 years [interquartile range (IQR) 12-36]. There were a total of 1360 infection-related hospitalisations in the follow-up period, incidence rate (IR) 13.1/1000 person-years [95% confidence interval (CI), 12.4; 13.8]. 206 relatives were hospitalised with viral infection, IR 1.8/1000 person-years (95% CI, 1.6; 2.0). There was no increased risk of hospitalisation due to infections, IR ratio (IRR) 0.99 (95% CI, 0.88; 1.12), nor specifically viral infections, IRR 0.87 (95% CI, 0.63; 1.19), in relatives of recipients with CMV compared to relatives of recipients without CMV. Also, no difference was seen in analyses stratified by transplant type, family relation and CMV serostatus. The risk of hospitalisation due to infection is not increased among first-degree relatives of transplant recipients with CMV infection compared to relatives of recipients without CMV.

Family Aggregation and Heritability of ESRD in Taiwan: A Population-Based Study

BACKGROUND

Aggregation of end-stage renal disease (ESRD) has been observed in families of European origin, as well as those of African origin. However, it is not well documented if this disease aggregates in Asian families. Furthermore, the contribution of genetic factors and shared environmental factors to family aggregation remains unclear.

STUDY DESIGN

Population-based cross-sectional cohort study.

SETTING & PARTICIPANTS

All 23,422,955 individuals registered in the Taiwan National Health Insurance Research Database in 2013. Among these, 47.45%, 57.45%, 47.29%, and 1.51% had a known parent, child, sibling, or twin, respectively. We identified 87,849 patients who had a diagnosis of ESRD.

PREDICTOR

Family history of ESRD.

OUTCOMES & MEASUREMENTS

ESRD and heritability defined as the proportion of phenotypic variance attributable to genetic factors.

RESULTS

Having an affected first-degree relative with ESRD was associated with an adjusted relative risk of 2.46 (95% CI, 2.32-2.62). Relative risks were 96.38 (95% CI, 48.3-192.34) for twins of patients with ESRD, 2.15 (95% CI, 2.02-2.29) for parents, 2.78 (95% CI, 2.53-3.05) for offspring, 4.96 (95% CI, 4.19-5.88) for siblings, and 1.66 (95% CI, 1.54-1.78) for spouses without genetic similarities. Heritability in this study was 31.1% to 11.4% for shared environmental factors and 57.5% for nonshared environmental factors.

LIMITATIONS

This was a registry database study and we did not have detailed information about clinical findings or the definite causes of ESRD.

CONCLUSIONS

This whole population-based family study in Asia confirmed, in a Taiwanese population, that a family history of ESRD is a strong risk factor for this disease. Moderate heritability was noted and environmental factors were related to disease. Family history of ESRD is an important piece of clinical information.

A Case-Based Analysis of Whether Living Related Donors Listed for Transplant Share ESRD Causes with Their Recipients

BACKGROUND AND OBJECTIVES

Two recent studies reported increased risk of ESRD after kidney donation. In both, the majority of ESRD was seen in those donating to a relative. Confounding this observation is that, in the absence of donation, relatives of those with ESRD are at increased risk for ESRD. Understanding the pathogenesis and risk factors for postdonation ESRD is critical for both donor selection and counseling.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We hypothesized that if familial relationship was an important consideration in pathogenesis, the donor and linked recipient would share ESRD etiology. We obtained information from the Organ Procurement and Transplantation Network (OPTN) on all living kidney donors subsequently waitlisted for a kidney transplant in the United States between January 1, 1996 and November 30, 2015, to determine (1) the donor-recipient relationship and (2) whether related donor-recipient pairs had similar causes of ESRD.

RESULTS

We found that a significant amount of information, potentially available at the time of listing, was not reported to the OPTN. Of 441 kidney donors listed for transplant, only 169 had information allowing determination of interval from donation to listing, and only 99 (22% of the total) had information on the donor-recipient relationship and ESRD etiology. Of the 99 donors, 87 were related to their recipient. Strikingly, of the 87, only a minority (23%) of donor-recipient pairs shared ESRD etiology. Excluding hypertension, only 8% shared etiology.

CONCLUSIONS

A better understanding of ESRD in donors requires complete and detailed data collection, as well as a method to capture all ESRD end points. This study highlights the absence of critical information that is urgently needed to provide a meaningful understanding of ESRD after kidney donation. We found that of living related donors listed for transplant, where both donor and recipient cause of ESRD is recorded, only a minority share ESRD etiology with their recipient.

A single nucleotide polymorphism in the UMOD promoter is associated with end stage renal disease

BACKGROUND

Several genome-wide association studies revealed that several variants of UMOD gene were related to the estimated glomerular filtration rate (eGFR), CKD or hypertension. In this study, we investigated the association between a common variant rs13333226 in the promoter region of UMOD gene and end stage renal disease (ESRD).

METHODS

Variant rs13333226 of UMOD gene was genotyped by using the ABI Real time TaqMan allelic discrimination assay in a case-control study including 638 unrelated patients with ESRD and 366 controls.

RESULTS

The frequency of UMOD SNP rs13333226 GG/GA genotype was significantly higher (36.83% vs. 20.22%, P = 4.02 × 10^-8) and the frequency of G allele was much higher (19.04% vs. 11.20%, P = 4.00 × 10^-6) in the patients with ESRD than in the controls. The G allele was associated with an increased risk of ESRD (odds ratio 2.30, 95% confidence interval 1.70-3.11, P = 6.10 × 10^-8). And G allele (odds ratio 2.33, 95% confidence interval 1.32-4.13, P = 3.65 × 10^-3) was associated independently with ESRD.

CONCLUSIONS

A common variation rs13333226 in the promoter region of UMOD gene was independently associated with ESRD in Han Chinese.

End Stage Renal Disease Predicts Increased Risk of Death in First Degree Relatives in the Norwegian Population

BACKGROUND

Increased risk of end stage renal disease (ESRD) and death in Norwegian living kidney donors has been reported, most of the donors were related to the recipient. The present study investigates risk of death in first degree relatives of ESRD patients.

METHODS

The Norwegian Population Registry, The Norwegian Cause of Death Registry and the Norwegian Renal Registry were linked. All citizens born in Norway, alive in 1960 and with at least one registered first degree relative were included; individuals who died during the first year of life were excluded. A cohort-design was used, ESRD in a first degree relative was the main exposure variable and death and causes of death were the main outcome variables. Cox regression statistics were used to investigate mortality risks.

RESULTS

5 130 600 individuals were included, 27 508 had at least one first degree relative with ESRD. 828 022 died during follow-up, of whom 4105 had a first degree relative with ESRD. Adjusted hazard ratio (aHR) for death was 1.13 (1.09-1.16) in individuals with a relative with ESRD compared to those without a relative with ESRD. Excluding known hereditary renal disease, aHR decreased to 1.12 (1.09-1.15). Cardiovascular death aHR was 1.15 (1.10-1.21), of which cerebrovascular death 1.34 (1.22-1.50). aHR for death due to non-hereditary renal/ureteric disease was 2.29 (1.81-2.91) with renal failure 1.80 (1.26-2.56) and glomerular disease 5.69 (3.88-8.34) as main contributors. Diabetes mellitus death aHR was 1.68 (1.35-2.10). Absolute mortality risks increased most for the oldest cohorts with excess mortality of 148 per 100.000 person years for the cohort born 1920-39 and 218 for the cohort born 1900-1919.

CONCLUSIONS

ESRD in first degree relatives was associated with increased hazard ratio for death. Death due to cardiovascular disease, renal disease and diabetes mellitus increased the most.

Renal Function Profile in White Kidney Donors: The First 4 Decades

Previous studies reported the risk of ESRD after kidney donation, but not the renal outcomes that precede ESRD. Here, we estimated the risk of proteinuria, reduced GFR, and ESRD in 3956 white kidney donors, assessed the contribution of postdonation hypertension and diabetes to these outcomes, and developed a risk calculator. After a mean±SD follow-up of 16.6±11.9 years, 215 (6.1%) donors developed proteinuria. Men had a higher risk of proteinuria (hazard ratio [HR], 1.56; 95% confidence interval [95% CI], 1.18 to 2.05; P<0.001) as did those with higher body mass index (HR, 1.10; 95% CI, 1.06 to 1.13; P<0.001). In all, 1410 (36%) donors reached an eGFR<60 ml/min per 1.73 m(2), and 112 (2.8%) donors had either an eGFR<30 ml/min per 1.73 m(2) or ESRD (28 donors developed ESRD). An eGFR<30 ml/min per 1.73 m(2) or ESRD associated with older age (HR, 1.07; 95% CI, 1.05 to 1.09; P<0.001), higher body mass index (HR, 1.08; 95% CI, 1.04 to 1.13; P<0.001), and higher systolic BP (HR, 1.02; 95% CI, 1.00 to 1.04; P=0.01) at donation. Postdonation diabetes and hypertension associated with a fourfold higher risk of proteinuria and a >2-fold higher risk of ESRD. Models predicting proteinuria and reduced eGFR performed well (C-index 0.77-1.00). In conclusion, severe reduction in GFR and ESRD after kidney donation were uncommon and were highly associated with postdonation diabetes and hypertension. Furthermore, information available before donation may predict long-term renal outcomes in white living kidney donors.

Investigating kidney donation as a risk factor for hypertension and microalbuminuria: findings from the Swiss prospective follow-up of living kidney donors

OBJECTIVES

To assess the role of nephrectomy as a risk factor for the development of hypertension and microalbuminuria.

DESIGN

Prospective, long-term follow-up study.

SETTING

Swiss Organ Living-Donor Health Registry.

PARTICIPANTS

All living kidney donors in Switzerland between 1993 and 2009.

INTERVENTIONS

Data on health status and renal function before 1 year and biennially after donation were collected.

PRIMARY AND SECONDARY OUTCOME MEASURES

Comparison of 1-year and 5-year occurrences of hypertension among normotensive donors with 1-year and 5-year estimates from the Framingham hypertension risk score. Multivariate random intercept models were used to investigate changes of albumin excretion after donation, correcting for repeated measurements and cofactors such as age, male gender and body mass index.

RESULTS

A total of 1214 donors contributed 3918 data entries with a completed biennial follow-up rate of 74% during a 10-year period. Mean (SD) follow-up of donors was 31.6 months (34.4). Median age at donation was 50.5 years (IQR 42.2-58.8); 806 donors (66.4%) were women. Donation increased the risk of hypertension after 1 year by 3.64 (95% CI 3.52 to 3.76; p<0.001). Those participants remaining normotensive 1 year after donation return to a risk similar to that of the healthy Framingham population. Microalbuminuria before donation was dependent on donor age but not on the presence of hypertension. After nephrectomy, hypertension became the main driver for changes in albumin excretion (OR 1.19; 95% CI 0.13 to 2.25; p=0.03) and donor age had no effect.

CONCLUSIONS

Nephrectomy propagates hypertension and increases susceptibility for the development of hypertension-induced microalbuminuria.

Race, Relationship and Renal Diagnoses After Living Kidney Donation

BACKGROUND

In response to recent studies, a better understanding of the risks of renal complications among African American and biologically related living kidney donors is needed.

METHODS

We examined a database linking U.S. registry identifiers for living kidney donors (1987-2007) to billing claims from a private health insurer (2000-2007 claims) to identify renal condition diagnoses categorized by International Classification of Diseases 9th Revision coding. Cox regression with left and right censoring was used to estimate cumulative incidence of diagnoses after donation and associations (adjusted hazards ratios, aHR) with donor traits.

RESULTS

Among 4650 living donors, 13.1% were African American and 76.3% were white; 76.1% were first-degree relatives of their recipient. By 7 years post-donation, after adjustment for age and sex, greater proportions of African American compared with white donors had renal condition diagnoses: chronic kidney disease (12.6% vs 5.6%; aHR, 2.32; 95% confidence interval [95% CI], 1.48-3.62), proteinuria (5.7% vs 2.6%; aHR, 2.27; 95% CI, 1.32-3.89), nephrotic syndrome (1.3% vs 0.1%; aHR, 15.7; 95% CI, 2.97-83.0), and any renal condition (14.9% vs 9.0%; aHR, 1.72; 95% CI, 1.23-2.41). Although first-degree biological relationship to the recipient was not associated with renal risk, associations of African American race persisted for these conditions and included unspecified renal failure and reported disorders of kidney dysfunction after adjustment for biological donor-recipient relationship.

CONCLUSIONS

African Americans more commonly develop renal conditions after living kidney donation, independent of donor-recipient relationship. Continued research is needed to improve risk stratification for renal outcomes among African American living donors.

The Irish Kidney Gene Project--Prevalence of Family History in Patients with Kidney Disease in Ireland

BACKGROUND

The prevalence of kidney disease (KD) due to inherited genetic conditions in Ireland is unknown. The aim of this study was to characterise an adult kidney disease population in Ireland and to identify familial clusters of kidney disease within the population.

METHODS

This was a multicenter cross-sectional study of patients with kidney disease in the Republic of Ireland, from January 2014 to September 2014, recruiting from dialysis units and out-patient renal departments. A survey was performed by collecting data on etiology of kidney disease and whether a family history of kidney disease exists. Medical records were cross-referenced to confirm the etiology of kidney disease.

RESULTS

A total of 1,840 patients were recruited with a mean age of 55.9 years (range 17-94.5) and a male predominance (n = 1,095; 59.5%). A positive family history was reported by 629 participants (34.2%). Excluding polycystic kidney disease (n = 134, 7.3%), a positive family history was reported by 495 participants (26.9%). Kidney disease due to an unknown etiology was the commonest etiology in the non-polycystic kidney disease group with a positive family history (10.6%, n = 67). Kidney diseases that are not classically associated with familial inheritance including tubulo-interstitial kidney disease, congenital abnormalities of the kidney and urinary tract and glomerulonephritis demonstrated familial clustering.

CONCLUSION

In an Irish non-polycystic kidney disease population, 26.9% reports a positive family history. The commonest etiology of kidney disease in the positive family history cohort, excluding autosomal dominant polycystic kidney disease, was kidney disease due to unknown etiology. Examining families with kidney disease provides an opportunity to better understand disease pathogenesis and potentially identify genetic predispositions to kidney disease.

Genetics of diabetic nephropathy: a long road of discovery

The global prevalence of diabetic nephropathy is rising in parallel with the increasing incidence of diabetes in most countries. Unfortunately, up to 40 % of persons diagnosed with diabetes may develop kidney complications. Diabetic nephropathy is associated with substantially increased risks of cardiovascular disease and premature mortality. An inherited susceptibility to diabetic nephropathy exists, and progress is being made unravelling the genetic basis for nephropathy thanks to international research collaborations, shared biological resources and new analytical approaches. Multiple epidemiological studies have highlighted the clinical heterogeneity of nephropathy and the need for better phenotyping to help define important subgroups for analysis and increase the power of genetic studies. Collaborative genome-wide association studies for nephropathy have reported unique genes, highlighted novel biological pathways and suggested new disease mechanisms, but progress towards clinically relevant risk prediction models for diabetic nephropathy has been slow. This review summarises the current status, recent developments and ongoing challenges elucidating the genetics of diabetic nephropathy.

Genomics in the renal clinic - translating nephrogenetics for clinical practice

Genetic Renal Disease (GRD) presents to mainstream clinicians as a mixture of kidney-specific as well as multi-organ entities, many with highly variable phenotype-genotype relationships. The rapid increase in knowledge and reduced cost of sequencing translate to new and additional approaches to clinical care. Specifically, genomic technologies to test for known genes, the development of pathways to research potential new genes and the collection of registry data on patients with mutations allow better prediction of outcomes. The aim of such approaches is to maximise personal and health-system utility from genomics for those affected by nephrogenetic disorders.