MO026CLINICAL AND MUTATIONAL SPECTRUM OF CHILDREN WITH AUTOSOMAL RECESSIVE AND AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE

Background and Aims Cystic kidney diseases are a heterogeneous group of chronic renal disease. Autosomal recessive polycystic kidney disease (ARPKD) is generally diagnosed in utero or at birth due to mutations in PKHD1 gene. Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disease commonly associated with mutations in PKD1 or PKD2. In this study, we aimed to investigate clinical and genetic features of ARPKD and ADPKD in a group of Turkish patients. Method A total of 69 children with genetically confirmed ARPKD (10 females, 11 males) or ADPKD (28 females, 20 males) from seven pediatric nephrology centers were included in this study. Demographic features, family history, clinical and laboratory findings at presentation and during 12 months intervals were collected. Results For ARPKD patients, the median age at diagnosis was 10.5 (IQR; 0.75-58.5) months. Consanguinity between parents was present in 11 patients (52.4%). At the time of diagnosis, 14 (66.7%) patients had eGFR<90 ml/min/1.73 m2. Mean duration of follow-up was 4.1±3,7 years. At the last visit, median eGFR was 74 (IQR; 43-126) ml/min/1.73m2. A total of 6 patients (28,6%) underwent a renal replacement therapy (RRT), 3 of them died in infancy and 2 of them had renal transplantation during follow up. All patients had bi-allelic PKHD1 mutation. For ADPKD patients, the mean age at diagnosis was 5.5±4.6 years. At the time of diagnosis 11 (22.9%) patients had eGFR<90 ml/min/1.73m2. Mean duration of follow-up was 2,7±2.3 years. At the last visit, median eGFR was 114 (IQR; 98-135) ml/min/1.73m2. Only one patient underwent a renal transplantation. A total of 42 patients (87.5%) had a heterozygous PKD1 mutation while 6 (12.5%) had a heterozygous PKD2 mutation. The rate of growth retardation, hypertension at diagnosis and progression to chronic kidney disease (CKD) were higher in patients with PKHD1 mutation than the patients with PKD1 or PKD2 mutation (p < 0.001, p < 0.001 and p = 0.001, respectively). In kidney survival analysis, mutation type, growth retardation at presentation, increased renal echogenity in ultrasonography were found as independent risk factors for progression to CKD. Conclusion Cystic kidney diseases are one of the most clinically and genetically heterogenous diseases. Differentiating them and establishing the predictors for CKD development is important to provide appropriate management including choosing appropriate donor in renal transplantation.

Prediction of Renal Prognosis in Patients with Autosomal Dominant Polycystic Kidney Disease Using PKD1/PKD2 Mutations

Autosomal dominant polycystic kidney disease (ADPKD) patients with PKD1 mutations, particularly those with truncating mutations, show poor prognosis. However, the differences in disease progression with different mutation types are unclear. Here, a comparative study was conducted on the renal prognosis of patients with ADPKD who were categorized based on genotype (PKD1 versus PKD2 mutation), mutation type (truncating mutation: nonsense, frameshift, splicing mutation, and large deletion; non-truncating mutation: substitution and in-frame deletion), and mutation position. A total of 123 patients visiting our hospital were enrolled. Renal prognosis was poor for those with PKD1 splicing, PKD1 frameshift, and PKD2 splicing mutations. Despite the truncating mutation, the renal prognosis was relatively favorable for patients with nonsense mutations. Three out of five patients with PKD2 mutation required renal replacement therapy before 58 years of age. In conclusion, we showed that renal prognosis differs according to mutation types in both PKD1 and PKD2, and that it was favorable for those with nonsense mutations among patients with PKD1 truncating mutations. It was also confirmed that renal prognosis was not always favorable in patients with PKD2 mutations. A detailed assessment of mutation types may be useful for predicting the renal prognosis of patients with ADPKD.

Genotype-Clinical Correlations in Polycystic Kidney Disease with No Apparent Family History

Background: Genetic characteristics of polycystic kidney disease (PKD) patients without apparent family history were reported to be different from those with a positive family history. However, the clinical course of PKD patients with no apparent family history is not well documented in the literature. Methods: We evaluated the relationship between genotype and the clinical course of 62 PKD patients with no apparent family history. Results: The annual decline of renal function was faster in the patients with PKD1/PKD2 mutation (PKD1 truncating [–3.08; 95% CI –5.30 to –0.87, p = 0.007], PKD1 nontruncating [–2.10; –3.82 to –0.38, p = 0.02], and PKD2 [–2.31; –4.40 to –0.23, p = 0.03]) than in the other patients without PKD1/PKD2 mutation. Similar results were obtained after adjustment for gender, age, estimated glomerular filtration rate (eGFR), height-adjusted total kidney volume (TKV), and mean arterial pressure (MAP). There was no significant difference in the annual decline of renal function among the different PKD1/PKD2 groups, but Kaplan-Meier analysis showed that progression to eGFR < 15 mL/min/1.73 m2 was significantly faster in PKD1 truncating group (p = 0.05). The annual rate of TKV increase was larger in the patients with PKD1/PKD2 mutation (PKD1 truncating [4.63; 95% CI 0.62–8.64, p = 0.03], PKD1 nontruncating [3.79; 0.55–7.03, p = 0.02], and PKD2 [2.11; –1.90 to 6.12, p = 0.29]) than in the other patients without PKD1/PKD2 mutation. Similar results were obtained after adjustment for gender, age, eGFR, and MAP. Conclusion: Detection of PKD1/PKD2 mutation, especially PKD1 truncating, is useful for predicting the renal outcome and rate of TKV increase in PKD patients with no apparent family history.