Autosomal dominant polycystic kidney disease (ADPKD) is heterogeneous with regard to genic and allelic heterogeneity, as well as phenotypic variability. The genotype-phenotype relationship in ADPKD is not completely understood. Here, we studied 741 patients with ADPKD from 519 pedigrees in the Genkyst cohort and confirmed that renal survival associated with PKD2 mutations was approximately 20 years longer than that associated with PKD1 mutations. The median age at onset of ESRD was 58 years for PKD1 carriers and 79 years for PKD2 carriers. Regarding the allelic effect on phenotype, in contrast to previous studies, we found that the type of PKD1 mutation, but not its position, correlated strongly with renal survival. The median age at onset of ESRD was 55 years for carriers of a truncating mutation and 67 years for carriers of a nontruncating mutation. This observation allows the integration of genic and allelic effects into a single scheme, which may have prognostic value.

The course of autosomal dominant polycystic kidney disease (ADPKD) varies among individuals, with some reaching ESRD before 40 years of age and others never requiring RRT. In this study, we developed a prognostic model to predict renal outcomes in patients with ADPKD on the basis of genetic and clinical data. We conducted a crosssectional study of 1341 patients from the Genkyst cohort and evaluated the influence of clinical and genetic factors on renal survival. Multivariate survival analysis identified four variables that were significantly associated with age at ESRD onset, and a scoring system from 0 to 9 was developed as follows: being male: 1 point; hypertension before 35 years of age: 2 points; first urologic event before 35 years of age: 2 points; PKD2 mutation: 0 points; nontruncating PKD1 mutation: 2 points; and truncating PKD1 mutation: 4 points. Three risk categories were subsequently defined as low risk (0-3 points), intermediate risk (4-6 points), and high risk (7-9 points) of progression to ESRD, with corresponding median ages for ESRD onset of 70.6, 56.9, and 49 years, respectively. Whereas a score #3 eliminates evolution to ESRD before 60 years of age with a negative predictive value of 81.4%, a score .6 forecasts ESRD onset before 60 years of age with a positive predictive value of 90.9%. This new prognostic score accurately predicts renal outcomes in patients with ADPKD and may enable the personalization of therapeutic management of ADPKD.

Autosomal dominant polycystic kidney disease (ADPKD) is one of the most commonly inherited renal diseases. ADPKD is a genetically heterogeneous disorder involving at least three different genes. PKD1, the major locus mapped to chromosome 16p13.3 accounts for approximately 85% of ADPKD cases. The search for mutations is a very important step in understanding the molecular mechanisms underlying ADPKD. Despite intense screening by many groups, only a small number of mutations have been described so far. We undertook the first study using denaturing gradient gel electrophoresis (DGGE) to scan for mutations in the non-duplicated region of the PKD1 gene in a large cohort of 146 French unrelated ADPKD patients. We successfully identified novel mutations: 3 are frameshift mutations, 2 nonsense mutations, 2 missense mutations, 1 is an insertion in the frame of 9 nucleotides, 3 intronic variations and several polymorphisms. One of these mutations is the fourth de novo mutation described in this gene. We also describe a family with possible clinical anticipation. DGGE is an effective method for detecting nucleotide changes in the PKD1 gene.

Despite the prominent role of IgA, particularly IgA1, in the pathogenesis of IgA nephropathy (IgAN), the precise role of this molecule in the process remains unclear. Four biotin-conjugated lectins in sandwich-type enzyme-linked immunosorbent assays were devised to determine the glycosylation profiles of total IgA and its subclasses. We took advantage of differential binding properties of these lectins to sugar residues to dissect the oligosaccharide chains O-linked to the hinge and those N-linked to the Fc region of total IgA and IgA subclasses in 47 patients with IgAN and an equal number of controls. The proportion of sialylated IgA1 was higher in patients compared with controls (p < 0.02), whereas IgA2 in patients appeared less well sialylated. A reduction of galactose in pathological IgA as detected by RCA-I became significant after treatment of the molecule with neuraminidase (p < 0.01). Defective galactosylation was also observed for patient IgA1 when it was probed with ECL, a lectin that has a specificity for Gal 1,4 N-acetylglucosamine groupings on N-linked oligosaccharides. The RCA and ECL results, therefore, suggest that increased sialylation on the IgA1 is on O-linked oligosaccharides in the hinge region. This was partly confirmed by a small increase in the binding of PNA to IgA1 from the patient group. This lectin binds preferentially to Gal 1,3 N-acetylgalactosamine groups that are found on O-linked oligosaccharides.

The involvement of dopamine (DA) receptor subtypes in regulation of renal phosphate transport by DA, either exogenous or locally synthesized from L-dihydroxyphenylalanine (L-dopa) was evaluated in opossum kidney (OK) cells with proximal tubular phenotype. DA synthesis from L-dopa by OK cells was abolished by carbidopa and benserazide, two dissimilar inhibitors of aromatic L-amino acid decarboxylase. L-Dopa stimulated cyclic AMP generation and inhibited Na-dependent Pi uptake, and these effects were abolished by carbidopa and benserazide. The effects of L-dopa or DA on cyclic AMP generation and on Na-Pi co-transport were mimicked by SKF 38393, a DA1 receptor agonist, and were potentiated by S-sulpiride, a DA2 receptor antagonist. Bromocriptine, a DA2 receptor agonist, blunted in a pertussis toxin-dependent manner parathyroid hormone (PTH)-induced cyclic AMP generation and inhibition of Pi uptake. In contrast with PTH, neither L-dopa nor DA affected significantly the cytosolic calcium concentration. These results support the involvement of DA1 and DA2 receptors, positively and negatively coupled into adenylate cyclase respectively, in modulation of renal phosphate transport.