Risk Prediction for Delayed Allograft Function: Analysis of the Deterioration of Kidney Allograft Function (DeKAF) Study Data

BACKGROUND

Delayed graft function (DGF) of a kidney transplant results in increased cost and complexity of management. For clinical care or a DGF trial, it would be ideal to accurately predict individual DGF risk and provide preemptive treatment. A calculator developed by Irish et al has been useful for predicting population but not individual risk.

METHODS

We analyzed the Irish calculator (IC) in the DeKAF prospective cohort (incidence of DGF = 20.4%) and investigated potential improvements.

RESULTS

We found that the predictive performance of the calculator in those meeting Irish inclusion criteria was comparable with that reported by Irish et al. For cohorts excluded by Irish: (a) in pump-perfused kidneys, the IC overestimated DGF risk; (b) in simultaneous pancreas kidney transplants, the DGF risk was exceptionally low. For all 3 cohorts, there was considerable overlap in IC scores between those with and those without DGF. Using a modified definition of DGF-excluding those with single dialysis in the first 24 h posttransplant-we found that the calculator had similar performance as with the traditional DGF definition. Studying whether DGF prediction could be improved, we found that recipient cardiovascular disease was strongly associated with DGF even after accounting for IC-predicted risk.

CONCLUSIONS

The IC can be a useful population guide for predicting DGF in the population for which it was intended but has limited scope in expanded populations (SPK, pump) and for individual risk prediction. DGF risk prediction can be improved by inclusion of recipient cardiovascular disease.

Outcomes of Kidney Donors With Impaired Fasting Glucose

BACKGROUND

Many kidney donor candidates with impaired fasting glucose (IFG) and all candidates with diabetes are currently excluded from kidney donation, fearing the development of an accelerated course of diabetic kidney disease in the remaining kidney.

METHODS

We studied mortality, proteinuria, and end-stage kidney disease (ESKD) in 8280 donors who donated between 1963 and 2007 according to donation fasting plasma glucose (FPG): <100 mg/dL (n = 6204), 100-125 mg/dL (n = 1826), and ≥126 mg/dL (n = 250).

RESULTS

Donors with IFG and those with FPG ≥126 mg/dL were older, less likely to be non-Hispanic White, had a higher body mass index, and were more likely to be related to their recipient. After 15.7 ± 10.5 y from donation to study close, 4.4% died, 29.4% developed hypertension, 13.8% developed proteinuria, and 41 (0.5%) developed ESKD. In both the logistic and Cox models, IFG was associated with a higher diabetes risk (adjusted hazard ratio [aHR], 1.65; 95% confidence interval [CI], 1.18-2.30) and hypertension (aHR, 1.35; 95% CI, 1.10-1.65; P = 0.003 for both), but not higher risk of proteinuria or ESKD. The multivariable risk of mortality in donors with ≥126 mg/dL was higher than the 2 other groups, but risks of proteinuria, cardiovascular disease, and reduced estimated glomerular filtration rate were similar to those with FPG <126 mg/dL. Three cases of ESKD developed in the 250 donors with FPG ≥126 mg/dL at 18.6 ± 10.3 y after donation (aHR, 5.36; 95% CI, 1.0-27.01; P = 0.04).

CONCLUSIONS

Donors with IFG and the majority of donors with ≥126 mg/dL do well and perhaps should not be routinely excluded from donation.

Correlation of Glomerular Size With Donor-Recipient Factors and With Response to Injury

BACKGROUND

Glomerular size in renal allografts is impacted by donor-recipient factors and response to injury. In serial biopsies of patients with well-functioning grafts, increased glomerular size correlates with better survival. However, no previous study has addressed the association of glomerular size at the time of a for-cause biopsy and clinical/histopathologic markers of injury, or effect on long-term graft outcome.

METHODS

Two cohorts of kidney transplant recipients enrolled in the Deterioration of Kidney Allograft Function study were evaluated. The prospective cohort (PC, n = 581): patients undergoing first for-cause kidney biopsy 1.7 ± 1.4 (mean ± SD) y posttransplant; and the cross-sectional cohort (CSC, n = 446): patients developing new-onset renal function deterioration 7.7 ± 5.6 y posttransplant. Glomerular planar surface area and diameter were measured on all glomeruli containing a vascular pole. Kidney biopsy was read centrally in a blinded fashion according to the Banff criteria.

RESULTS

Glomerular area was significantly higher in the CSC than the PC; time from transplant to indication biopsy was associated with glomerular area in both cohorts (P values ≤ 0.001). Glomerular area was associated with indices of microvascular inflammation (glomerulitis, peritubular capillary infiltrates; P values ≤ 0.001) and segmental glomerulosclerosis (P value < 0.0001). In the CSC, higher glomerular area was associated with higher estimated glomerular filtration rate (P value ≤ 0.001) and increased graft survival after accounting for microvascular inflammation (adjusted hazard ratio = 0.967; 95% confidence interval: 0.948-0.986; hazard ratio in biopsies without evidence of diabetes or antibody mediated rejection = 0.919, 95% confidence interval: 0.856-0.987).

CONCLUSIONS

Glomerular size is associated with histopathologic features present at the time of indication biopsy and with increased graft survival in the CSC.

Outcomes of Kidney Allograft and Recipient Survival After Liver Transplantation by Induction Type in the United States

There are several choices for induction immunosuppression in kidney-after-liver transplantation. We used the Scientific Registry of Transplant Recipients database. We assessed all kidney-after-liver transplant recipients in the United States between 1/1/2000 and 7/31/2017 to study kidney graft and patient outcomes by induction type. We only included patients discharged on tacrolimus and mycophenolate with or without steroids and had a negative crossmatch before kidney engraftment. We grouped recipients by kidney induction type into the following 3 groups: depletional (n = 550), nondepletional (n = 434), and no antibody induction (n = 144). We studied patient and kidney allograft survival using Cox proportional hazard regression, with transplant center included as a random effect. Models were adjusted for liver induction regimen, recipient and donor age, sex, human leukocyte antigen mismatches, payor type, living donor kidney transplantation, dialysis status, time from liver engraftment, hepatitis C virus status, and the presence of diabetes mellitus at time of kidney transplantation and transplantation year. The 6-month and 1-year rejection rates did not differ between groups. Compared with no induction, neither depletional nor nondepletional induction was associated with an improved recipient or graft survival in the multivariable models. Depletional induction at the time of liver transplantation was associated with worse patient survival after kidney transplantation (hazard ratio [HR], 1.7; 95% confidence interval [CI], 1.09-2.67; P = 0.02). Living donor kidney transplantation was associated with a 48.1% improved graft survival (HR, 0.52; 95% CI, 0.33-0.82; P = 0.00). In conclusion, in the settings of a negative cross-match and maintenance with tacrolimus and mycophenolate, induction use was not associated with a patient or graft survival benefit in kidney-after-liver transplantations.

Intermediate Renal Outcomes, Kidney Failure, and Mortality in Obese Kidney Donors

BACKGROUND

Obesity is associated with the two archetypal kidney disease risk factors: hypertension and diabetes. Concerns that the effects of diabetes and hypertension in obese kidney donors might be magnified in their remaining kidney have led to the exclusion of many obese candidates from kidney donation.

METHODS

We compared mortality, diabetes, hypertension, proteinuria, reduced eGFR and its trajectory, and the development of kidney failure in 8583 kidney donors, according to body mass index (BMI). The study included 6822 individuals with a BMI of <30 kg/m2, 1338 with a BMI of 30-34.9 kg/m2, and 423 with a BMI of ≥35 kg/m2. We used Cox regression models, adjusting for baseline covariates only, and models adjusting for postdonation diabetes, hypertension, and kidney failure as time-varying covariates.

RESULTS

Obese donors were more likely than nonobese donors to develop diabetes, hypertension, and proteinuria. The increase in eGFR in obese versus nonobese donors was significantly higher in the first 10 years (3.5 ml/min per 1.73m2 per year versus 2.4 ml/min per 1.73m2 per year; P<0.001), but comparable thereafter. At a mean±SD follow-up of 19.3±10.3 years after donation, 31 (0.5%) nonobese and 12 (0.7%) obese donors developed ESKD. Of the 12 patients with ESKD in obese donors, 10 occurred in 1445 White donors who were related to the recipient (0.9%). Risk of death in obese donors was not significantly increased compared with nonobese donors.

CONCLUSIONS

Obesity in kidney donors, as in nondonors, is associated with increased risk of developing diabetes and hypertension. The absolute risk of ESKD is small and the risk of death is comparable to that of nonobese donors.

Risk of kidney disease after living kidney donation

Living donor kidney transplantation benefits the recipient. However, kidney failure can occur in a small fraction of donors — the risk is not uniform but varies according to donor characteristics. Studies to date have failed to match on important factors, such as era, environment or family history. Long-term studies with well-matched healthy controls are therefore needed.

Precision Dosing for Tacrolimus Using Genotypes and Clinical Factors in Kidney Transplant Recipients of European Ancestry

Genetic variation in the CYP3A4 and CYP3A5 (CYP3A4/5) genes, which encode the key enzymes in tacrolimus metabolism, is associated with tacrolimus clearance and dose requirements. Tacrolimus has a narrow therapeutic index with high intra- and intersubject variability, in part because of genetic variation. High tacrolimus clearance and low trough concentration are associated with a greater risk for rejection, whereas high troughs are associated with calcineurin-induced toxicity. The objective of this study was to develop a model of tacrolimus clearance with a dosing equation accounting for genotypes and clinical factors in adult kidney transplant recipients of European ancestry that could preemptively guide dosing. Recipients receiving immediate-release tacrolimus for maintenance immunosuppression from 2 multicenter studies were included. Participants in the GEN03 study were used for tacrolimus model development (n = 608 recipients) and was validated by prediction performance in the DeKAF Genomics study (n = 1361 recipients). Nonlinear mixed-effects modeling was used to develop the apparent oral tacrolimus clearance (CL/F) model. CYP3A4/5 genotypes and clinical covariates were tested for their influence on CL/F. The predictive performance of the model was determined by assessing the bias (median prediction error [ME] and median percentage error [MPE]) and the precision (root median squared error [RMSE]) of the model. CYP3A5*3, CYP3A4*22, corticosteroids, calcium channel blocker and antiviral drug use, age, and diabetes significantly contributed to the interindividual variability of oral tacrolimus apparent clearance. The bias (ME, MPE) and precision (RMSE) of the final model was good, 0.49 ng/mL, 6.5%, and 3.09 ng/mL, respectively. Prospective testing of this equation is warranted.

Incidence, risk factors, and long-term outcomes associated with antibody-mediated rejection - The long-term Deterioration of Kidney Allograft Function (DeKAF) prospective cohort study

Major gaps remain in our understanding of antibody-mediated rejection (AMR) after kidney transplant. We examined the incidence, risk factors, response to treatment, and effects on outcomes of AMR at seven transplant programs in the long-term Deterioration of Kidney Allograft Function prospective study cohort. Among 3131 kidney recipients, there were 194 observed AMR cases (6.2%) during (mean ± SD) 4.85 ± 1.86 years of follow-up. Time to AMR was 0.97 ± 1.17 (median, 0.48) years. Risk factors for AMR included younger recipient age, human leukocyte antigen DR mismatches, panel-reactive antibody >0%, positive T- or B-cell cross-match, and delayed graft function. Compared with no AMR, the adjusted time-dependent hazard ratio for death-censored graft failure is 10.1 (95% confidence interval, 6.5-15.7) for all AMR patients, 4.0 (2.5, 9.1) for early AMR (<90 days after transplant), and 24.0 (14.0-41.1) for late AMR (≥90 days after transplant). Patients were treated with different therapeutic combinations. Of 194 kidney transplant recipients with AMR, 50 (25.8%) did not respond to treatment, defined as second AMR within 100 days or no improvement in estimated glomerular filtration rate by 42 days. Long-term outcomes after AMR are poor, regardless of the initial response to treatment. Better prevention and new therapeutic strategies are needed to improve long-term allograft survival.

i-IFTA and chronic active T cell-mediated rejection: A tale of 2 (DeKAF) cohorts

Inflammation in areas of fibrosis (i-IFTA) in posttransplant biopsies is part of the diagnostic criteria for chronic active TCMR (CA TCMR -- i-IFTA ≥ 2, ti ≥ 2, t ≥ 2). We evaluated i-IFTA and CA TCMR in the DeKAF indication biopsy cohorts: prospective (n = 585, mean time to biopsy = 1.7 years); cross-sectional (n = 458, mean time to biopsy = 7.8 years). Grouped by i-IFTA scores, the 3-year postbiopsy DC-GS is similar across cohorts. Although a previous acute rejection episode (AR) was more common in those with i-IFTA on biopsy, the majority of those with i-IFTA had not had previous AR. There was no association between type of previous AR (AMR, TCMR) and presence of i-IFTA. In both cohorts, i-IFTA was associated with markers of both cellular (increased Banff i, t, ti) and humoral (increased g, ptc, C4d, DSA) activity. Biopsies with i-IFTA = 1 and i-IFTA ≥ 2 with concurrent t ≥ 2 and ti ≥ 2 had similar DC-GS. These results suggest that (a) i-IFTA≥1 should be considered a threshold for diagnoses incorporating i-IFTA, ti, and t; (b) given that i-IFTA ≥ 2,t ≥ 2, ti ≥ 2 can occur in the absence of preceding TCMR and that the component histologic scores (i-IFTA,t,ti) each indicate an acute change (albeit i-IFTA on the nonspecific background of IFTA), the diagnostic category "CA TCMR" should be reconsidered.

Pharmacogenomics in kidney transplant recipients and potential for integration into practice

WHAT IS KNOWN AND OBJECTIVE

Pharmacogenomic biomarkers are now used in many clinical care settings and represent one of the successes of precision medicine. Genetic variants are associated with pharmacokinetic and pharmacodynamic changes leading to medication adverse effects and changes in clinical response. Actionable pharmacogenomic variants are common in transplant recipients and have implications for medications used in transplant, but yet are not broadly incorporated into practice.

METHODS

From the Clinical Pharmacogenetics Implementation Consortium and Dutch Pharmacogenetics Working Group guidelines, and PharmGKB databases, 12 pharmacogenomic genes with 30 variants were selected and used to create diplotypes and actionable pharmacogenomic phenotypes. A total of 853 kidney allograft recipients who had genomic information available from a genome-wide association study were included.

RESULTS

Each recipient had at least one actionable pharmacogenomic diplotype/phenotype, whereas the majority (58%) had three or four actionable diplotypes/phenotypes and 17.4% had five or more among the 12 genes. The participants carried actionable diplotypes/phenotypes for multiple medications, including tacrolimus, azathioprine, clopidogrel, warfarin, simvastatin, voriconazole, antidepressants and proton-pump inhibitors.

WHAT IS NEW AND CONCLUSION

Pharmacogenomic variants are common in transplant recipients, and transplant recipients receive medications that have actionable variants.

CLINICAL TRIAL

Genomics of Transplantation, clinicaltrials.gov (NCT01714440).

Pediatric retransplantation of the liver: A prognostic scoring tool

Few prognostic models have been created in children that receive liver retransplantation (rLT). We examined the SRTR database of 731 children that underwent second liver transplant between 2002 and 2018. Proportional hazards models using backward variable selection were used to identify recipient, donor, and surgical characteristics associated with survival. A simple prognostic scoring system or nomogram (ie, each risk factor was weighted on a five-point scale) was constructed based on the fitted model. Recipient age (P < .001), MELD/PELD (P < .001), recipient ventilated (P = .003), donor cause of death (P = .024), graft type (P = .045), first graft loss due to biliary tract complications (P = .048), and survival time of the first graft (P = .006) were significant predictors of retransplant survival. The bias-corrected Harrell's C-index for the multivariable model was 0.63. Survival was significantly different (P < .001) for those at low risk (0-4 points), medium risk (5-7 points), and high risk (8+ points). Survival was equivalent between low risk pediatric second transplant recipients and pediatric primary liver transplant recipients (P = .67) but significantly worse for medium- (P < .001) and high-risk (P < .001) recipients. With simple clinical characteristics, this scoring tool can modestly discriminate between those children at high risk and those children at low risk of poor outcomes after second liver transplant.

Inflammation in areas of fibrosis: The DeKAF prospective cohort

Inflammation in areas of fibrosis (i-IFTA) in posttransplant biopsy specimens has been associated with decreased death-censored graft survival (DC-GS). Additionally, an i-IFTA score ≥ 2 is part of the diagnostic criteria for chronic active TCMR (CA TCMR). We examined the impact of i-IFTA and t-IFTA (tubulitis in areas of atrophy) in the first biopsy for cause after 90 days posttransplant (n = 598); mean (SD) 1.7 ± 1.4 years posttransplant. I-IFTA, present in 196 biopsy specimens, was strongly correlated with t-IFTA, and Banff i. Of the 196, 37 (18.9%) had a previous acute rejection episode; 96 (49%) had concurrent i score = 0. Unlike previous studies, i-IFTA = 1 (vs 0) was associated with worse 3-year DC-GS: (i-IFTA = 0, 81.7%, [95% CI 77.7 to 85.9%]); i-IFTA = 1, 68.1%, [95% CI 59.7 to 77.6%]; i-IFTA = 2, 56.1%, [95% CI 43.2 to 72.8%], i-IFTA = 3, 48.5%, [95% CI 31.8 to 74.0%]). The association of i-IFTA with decreased DC-GS remained significant when adjusted for serum creatinine at the time of the biopsy, Banff i, ci and ct, C4d and DSA. T-IFTA was similarly associated with decreased DC-GS. Of these indication biopsies, those with i-IFTA ≥ 2, without meeting other criteria for CA TCMR had similar postbiopsy DC-GS as those with CA TCMR. Those with i-IFTA = 1 and t ≥ 2, ti ≥ 2 had postbiopsy DC-GS similar to CA TCMR. Biopsies with i-IFTA = 1 had similar survival as CA TCMR when biopsy specimens also met Banff criteria for TCMR and/or AMR. Studies of i-IFTA and t-IFTA in additional cohorts, integrating analyses of Banff scores meeting criteria for other Banff diagnoses, are needed.

Re-hospitalization after pediatric kidney transplant: A single-center study

BACKGROUND

Little data exist on re-hospitalization rates in pediatric kidney recipients (KTx) particularly with the evolution of transplant immunosuppression.

METHODS

In a single-center, retrospective study of pediatric KTx between 2006 and 2016, we assessed re-hospitalization after KTx admission, stratified by whether the re-admit was early (<30 days post-KTx discharge) or late (>30 days), and compared two different immunosuppression eras (one with and one without steroids).

RESULTS

Of 197 KTx, 156 (79%) patients were re-hospitalized in 1st year, 85 (56%) within 30 days of discharge (total 490 1st year re-hospitalizations). Younger age was associated with early and late re-hospitalizations. African American race was associated with early re-hospitalizations. Of the 123 and 74 discharged on steroid-avoidance (maintenance immunosuppression included MMF in 95%; FK in 50%; CSA in 50%) and steroid-inclusive (AZA in 66%; MMF in 34%; FK in 30%; CSA in 70%), re-hospitalization rates, timing post-transplant, length, and number were not significantly different (P .38; .1; .56; .11). Admission diagnoses analysis demonstrated that steroid-avoidance recipients had anemia/leucopenia/thrombocytopenia, significantly more often, as one of their admission diagnoses (16% vs 4%; P < .001) and had a rejection diagnosis significantly less often (6% vs 18%; P < .001). Infection diagnoses were not statistically different between groups. Re-hospitalization, early or late, did not predict worse graft/ patient survival but predicted further hospitalizations.

CONCLUSIONS

Re-hospitalization is common after pediatric transplant discharge and predicts further hospitalization regardless of discharge on or off steroids.

Medication adherence is associated with an increased risk of cancer in kidney transplant recipients: a cohort study

Background

Nonadherence to posttransplant immunosuppressive medication is associated with increased rates of rejection and graft loss, yet it is unknown to what degree ideal adherence is associated with the sequelae of overimmunosuppression. Specifically, we questioned whether excellent adherence increased the posttransplant cancer risk.

Methods

Between August 1998 and August 2006, 195 consenting kidney transplant recipients had electronic monitoring of theirimmunosuppressive medication adherence.

Results

Based on their average quantitative adherence to a single immunosuppressant drug over the first 6 months posttransplant, recipients were grouped into adherence tertiles (highest, >97.9% adherence; middle, 91-97.8%; lowest, <91%). The cumulative incidence of cancer was calculated for patients in each tertile, treating death as a competing risk. The association between adherence and cancer rate was calculated after adjusting for recipient risk factors, using a competing risk proportional hazards model. The median duration of follow-up was 10.1 years. The 10-year estimated cumulative cancer incidence was 59.4% in the most adherent, 36.1% in the middle group and 38.1% in the least adherent group (P = 0.006). Excluding nonmelanocytic skin cancers, cancer incidence remained significantly higher in the highest adherence group (P = 0.002).

Conclusions

These data provide additional support for the need to individualize immunosuppression to minimize both rejection and immunosuppressive drug-related complications including cancer.

Long-term outcomes of pediatric kidney transplant recipients with a pretransplant malignancy

A childhood malignancy can rarely progress to ESRD requiring a KT. To date, few reports describe long-term outcomes of pediatric KT recipients with a pretransplant malignancy. Between 1963 and 2015, 884 pediatric (age: 0-17 years old) recipients received 1055 KTs at our institution. KT outcomes were analyzed in children with a pretransplant malignancy. We identified 14 patients who had a pretransplant malignancy prior to KT; the majority were <10 years old at the time of KT. Ten (71%) patients received their grafts from living donors, the majority of which were related to the recipient. Wilms' tumor was the dominant type of pretransplant malignancy, seen in 50% of patients. The other pretransplant malignancy types were EBV-positive lymphoproliferative disorders, non-EBV-positive lymphoma, leukemia, neuroblastoma, soft-tissue sarcoma, and ovarian cancer. Ten of the 14 patients received chemotherapy as part of their pretransplant malignancy treatment. Graft survival at 1, 3, and 5 years was 93%, 83%, and 72%, respectively. Patient survival at 1, 5, and 10 years was 100%, 91%, and 83%, respectively. Six (40%) patients suffered AR following KT; half of them had their first episode of AR within 1 month of KT. Our single-center experience demonstrates that pediatric KT recipients with a previously treated pretransplant malignancy did not exhibit worse outcomes than other pediatric KT patients.

Rapid discontinuation of prednisone in kidney transplant recipients from at-risk subgroups: an OPTN/SRTR analysis

Although rapid discontinuation of prednisone (RDP) after kidney transplantation has been successful in low-risk recipients, there is concern about RDP use in recipients at increased risk for rejection or recurrent disease. Using SRTR, we compared outcomes for RDP versus maintenance prednisone-treated recipients for all adult 1st and 2nd transplants (n = 169 479) and the following 1st transplant subgroups: African American (AA); highly sensitized; those with a potentially recurrent disease; and pediatric recipients. For all adult 1st LD and DD transplants, RDP was associated with better patient and graft survival. For all LD subgroups, RDP and maintenance prednisone were associated with similar patient, graft, and death-censored (DC) graft survival. For 1st transplant DD subgroups, RDP was associated with better patient survival in AA, those with potentially recurrent disease, and pediatric recipients; graft survival with RDP was better in AAs. For adult 2nd DD transplants, RDP was associated with worse DC-graft survival. Importantly, for all differences, the effect size was small. With the exception of 2nd DD transplants, RDP protocols can be used without decreasing patient or graft survival for subgroups of 1st DD and LD kidney transplant recipients and for 2nd LD transplant recipients, at increased risk of rejection or recurrent disease.

Tacrolimus troughs and genetic determinants of metabolism in kidney transplant recipients: A comparison of four ancestry groups

Tacrolimus trough and dose requirements vary dramatically between individuals of European and African American ancestry. These differences are less well described in other populations. We conducted an observational, prospective, multicenter study from which 2595 kidney transplant recipients of European, African, Native American, and Asian ancestry were studied for tacrolimus trough, doses, and genetic determinants of metabolism. We studied the well-known variants and conducted a CYP3A4/5 gene-wide analysis to identify new variants. Daily doses, and dose-normalized troughs were significantly different between the four groups (P < .001). CYP3A5*3 (rs776746) was associated with higher dose-normalized tacrolimus troughs in all groups but occurred at different allele frequencies and had differing effect sizes. The CYP3A5*6 (rs10264272) and *7 (rs413003343) variants were only present in African Americans. CYP3A4*22 (rs35599367) was not found in any of the Asian ancestry samples. We identified seven suggestive variants in the CYP3A4/5 genes associated with dose-normalized troughs in Native Americans (P = 1.1 × 10^-5 -8.8 × 10^-6 ) and one suggestive variant in Asian Americans (P = 5.6 × 10^-6 ). Tacrolimus daily doses and dose-normalized troughs vary significantly among different ancestry groups. We identified potential new variants important in Asians and Native Americans. Studies with larger populations should be conducted to assess the importance of the identified suggestive variants.