Co-Inheritance of Autosomal Dominant Polycystic Kidney Disease and Naevoid Basal Cell Carcinoma Syndrome: Effects on Renal Progression

Abstract

The calcium signalling and hedgehog (HH) signalling pathways operate in the primary cilium. Abnormalities in these pathways cause autosomal dominant polycystic kidney disease (ADPKD) and naevoid basal cell carcinoma syndrome (NBCCS) respectively. Several reports have proposed that hyperactivation of the HH pathway in animal models of polycystic kidney disease affects normal renal development and renal cyst phenotype. A family with 2 cases (a proband and her sister) of ADPKD and NBCCS coinheritance led us to investigate whether interactions may be present in the 2 pathways. The effect of HH pathway hyperactivation (due to c.573C>G mutation on PTCH1 gene that cause NBCCS) on renal ADPKD progression in the proband was compared to 18 age- and sex-matched ADPKD patients in a 9-year, prospective, follow-up study. Blood pressure, total kidney volume, estimated glomerular filtration rate, plasma copeptin, urine excretion of albumin, total protein and monocyte chemoattractant protein-1 (MCP-1) were analysed. Data for the sibling was not available. In the ADPKD group, blood pressure and estimated glomerular filtration rate were within normal values, and total kidney volume and MCP-1 increased (p < 0.01) throughout the study. In comparison, during the 9-year follow-up, the proband showed persistent hypertension (from 125/85 to 140/95 mm Hg), low total kidney volume (75 and 61% of median ADPKD), and a ninefold increase in urine MCP-1. We found no differences in urine excretion of albumin or plasma copeptin values. These results suggest that HH hyperactivation may play a minimal role in ADPKD progression. These observations can help to clarify the clinical impact of affected pathways in renal development and cystogenesis in humans.

Keywords: Autosomal dominant polycystic kidney disease; Co-inheritance; Hedgehog signalling; Naevoid basal cell carcinoma syndrome; PTCH1 gene mutation.