Phenotype and renal outcomes of patients with congenital arginine vasopressin resistance

ABSTRACT Background and hypothesis The clinical phenotype and long-term outcomes of patients with congenital arginine vasopressin-resistance (AVP-R) have not been well evaluated. This study investigated the clinical features, treatment modalities and renal outcomes of patients with AVP-R. Methods Twenty-seven patients (male:female = 21:6, mean age = 22 ± 17 years) with genetically confirmed AVP-R from 18 unrelated Taiwanese families were included. Genomic DNA extracted from blood leukocytes was analyzed for AVPR2 and AQP2 mutations. Clinical presentations, laboratory findings, management and follow-up data, including analyses of renal function changes, were evaluated. Results Seventeen patients from 12 X-linked recessive families harbored 11 different AVPR2 mutations, including three novel small deletions and two large deletion mutations. Eight patients from five autosomal recessive (AR) families harbored three different AQP2 mutations (Q57P, G100V, V168Rfs*32) and two patients from one autosomal dominant (AD) family harbored a novel AQP2 R253Dfs*82 mutation. The median ages at onset of polyuria and polydipsia and at clinical diagnosis of AVP-R were 0.7 (range 2 months–2.5 years) and 11.7 (range 0.7–21.5) years, respectively. Three-quarters of patients were treated with oral hydrochlorothiazide alone or combined with amiloride, and one-third received indomethacin. Intrafamilial phenotypic heterogeneity was observed in one family harboring the AVPR2 F178L mutation. Seven patients exhibited persistent non-obstructive hydroureteronephrosis. At a median follow-up of 16.6 (2.2–25.7) years, seven patients (26%) had progressed to chronic kidney disease (CKD, stage III–V), of whom three (AVPR2 mutation = 2, AD AQP2 R253Dfs*82 = 1) were dependent on dialysis. An earlier age of onset, higher serum osmolality, larger daily urine volume and hydroureteronephrosis at first presentation were independent risk factors for CKD progression. Conclusions Non-obstructive hydroureteronephrosis is a common complication of congenital AVP-R. CKD frequently develops in patients with phenotypically severe congenital AVP-R, independent of AVPR2 or AQP2 mutation.