Association between genotype and phenotype in uromodulin-associated kidney disease

Abstract

Background and objectives: Uromodulin-associated kidney disease (UAKD) is an autosomal dominant disease caused by uromodulin (UMOD) gene mutations. This study explored genotype-phenotype correlations by examining the relationship between the type of UMOD mutation and the age at onset of ESRD.

Design, setting, participants & measurements: Extensive bibliographic research was used to ascertain patient-level data of all patients with UAKD published up to October 2011. Data included sex; ages at onset of hyperuricemia, gout, and ESRD; and UMOD genotype. Kaplan-Meier analysis and Cox proportional hazards models fitted with shared gamma frailty terms to adjust for within-family correlations were used to model time to event.

Results: Thirty-one peer-reviewed publications reporting on 202 patients from 74 families with 59 different UMOD mutations were included. Median ages at onset of hyperuricemia, gout, and ESRD were 24, 40, and 56 years, respectively. Men developed gout and ESRD significantly earlier than did women (age at ESRD was 50 years for men and 60 for women; P=0.04, shared frailty model). Median ages at ESRD development were lowest with Cys77Tyr (37.5 years) and highest with Gln316Pro (65.5 years) UMOD mutations. Onset of ESRD was significantly earlier with UMOD mutations located within the epidermal growth factor domains 2 and 3 (range, 45-52 years; P<0.01 and 0.04, respectively) compared with the cysteine-rich domains (range, 60-65 years; by shared frailty model).

Conclusions: The UMOD genotype is related to the clinical phenotype of UAKD. This finding may assist in counseling of patients.

Figure 1.

Kaplan-Meier survival curves stratified by the six UMOD mutations with the greatest number of affected individuals comparing the time to ESRD. Differences in time to ESRD were significant. The difference between median time to ESRD in p.Cys77Tyr (C77Y) and p.Met229Arg (M229R) mutations was almost 30 years. MMA = median manifestation age; N = number of individuals with known symptom status.