We found all ARPKD cases without PKHD1 point mutations to be phenocopies, and none to be explained by biallelic PKHD1 copy number variations. Screening for copy number variations is recommended in patients with a heterozygous point mutation.

Transient receptor potential canonical‐6 (TRPC6) ion channels, expressed at high levels in podocytes of the filtration barrier, are recently implicated in the pathogenesis of various forms of proteinuric kidney diseases. Indeed, inherited or acquired up‐regulation of TRPC6 activities are suggested to play a role in podocytopathies. Yet, we possess limited information about the regulation of TRPC6 in human podocytes. Therefore, in this study, we aimed at defining how the protein kinase C (PKC) system, one of the key intracellular signalling pathways, regulates TRPC6 function and expression. On human differentiated podocytes, we identified the molecular expressions of both TRPC6 and several PKC isoforms. We also showed that TRPC6 channels are functional since the TRPC6 activator 1‐oleoyl‐2‐acetyl‐sn‐glycerol (OAG) induced Ca2+‐influx to the cells. By assessing the regulatory roles of the PKCs, we found that inhibitors of the endogenous activities of classical and novel PKC isoforms markedly augmented TRPC6 activities. In contrast, activation of the PKC system by phorbol 12‐myristate 13‐acetate (PMA) exerted inhibitory actions on TRPC6 and suppressed its expression. Importantly, PMA treatment markedly down‐regulated the expression levels of PKCα, PKCβ, and PKCη reflecting their activation. Taken together, these results indicate that the PKC system exhibits a ‘tonic’ inhibition on TRPC6 activity in human podocytes suggesting that pathological conditions altering the expression and/or activation patterns of podocyte‐expressed PKCs may influence TRPC6 activity and hence podocyte functions. Therefore, it is proposed that targeted manipulation of certain PKC isoforms might be beneficial in certain proteinuric kidney diseases with altered TRPC6 functions.

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Background: In clinical practice, the possible diagnosis of tuberous sclerosis or polycystic kidney disease is primarily based on clinical criteria, which can later be verified by genetic testing. But in the case of TSC2/PKD1 contiguous gene syndrome (TSC2/PKD1-CGS), the renal appearance of the disease is more serious. Therefore, early genetic analysis is recommended. Methods: Herein we present the report of four children with TSC2/PKD1-CGS, one involving the NTHL1 gene. We aim to emphasize the importance of genetic testing in this rare syndrome. Results: During the follow-up of tuberous sclerosis and polycystic kidney disease patients, it is essential to reappraise the diagnosis if the clinical symptoms’ appearance or onset time is unusual. Targeted genetic testing is recommended. However, early tumor formation necessitates the extension of genetic analysis. Conclusions: An appropriate evaluation of the phenotype is the cornerstone of diagnosing the rare TSC2/PKD1-CGS with the help of genetic results. In addition, malignant tumors could draw attention to an infrequent large deletion.