Diagnosis of Biliary Hamartomatosis in Kidney Transplant Recipient affected by ADPKD

Abstract

Biliary hamartomas (BH) are rare benign lesions of the liver characterized by a dilation of a variable number of small biliary ducts, usually surrounded by abundant fibrotic tissue. These malformations are due to an aberrant remodelling of the ductal plate, that is the embryonic structure generating the normal biliary tree. BH are usually asymptomatic, but in rare cases they can be associated with jaundice, heartburn and fever. Evidences for a sharing of similar pathological pathways between BH and adult dominant polycystic kidney disease (ADPKD) are widely reported. These similarities induce an increased neoplastic risk transformation in both conditions. This risk is even greater in immunosuppressed patients. The diagnosis of BH by imaging is not easy, especially in the context of ADPKD. We present a clinical case of a 54-year-old kidney transplant recipient affected by ADPKD in which BH, previously undetected, was for the first time suspected on routine ultrasound scan and confirmed with MRI 4 years after renal transplantation. Demodulation of proliferative signals induced by immunosuppressive therapy, and particularly by calcineurin inhibitors, could cause an enlargement of AB and increase the risk of neoplastic transformation. Our case-report suggests a close imaging follow-up may be needed in ADPKD patients with BH, especially if transplanted. High sensitivity techniques, such as CEUS and MRI, should be preferred to conventional ultrasound.

Keywords: Biliary Hamartomatosis, Kidney Transplant, ADPKD

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The pathway of vasopressin as a pharmacological target in nephrology: a narrative review

Abstract

ADH is a hormone secreted by neurohypophysis that plays different roles based on the target organ. At the renal level, this peptide is capable of causing electrolyte-free water absorption, thus playing a key role in the hydro-electrolytic balance. There are pathologies and disorders that jeopardize this balance and, in this field, ADH receptor inhibitors such as Vaptans could play a key role. By inhibiting the activation pathway of vasopressin, they are potentially useful in euvolemic and hypervolemic hypotonic hyponatremia. However, clinical trials in heart failure have not given favourable results on clinical outcomes. Even in SIADH, despite their wide use, there is no agreement by experts on their use.

Since vaptans inhibit the cAMP pathway in tubular cells, their use has been proposed to inhibit cystogenesis. A clinical trial has shown favourable effects on ADPKD progression.

Because vaptans have been shown to be effective in models of renal cysts disorders other than ADPKD, their use has been proposed in diseases such as nephronophthisis and recessive autosomal polycystic disease. Other possible uses of vaptans could be in kidney transplantation and cardiorenal syndrome.

Due to the activity of ADH in coagulation and haemostasis, ADH’s activation pathway by Desmopressin Acetate could be a useful strategy to reduce the risk of bleeding in biopsies in patients with haemorrhagic risk.

 

Keyword: vasopressin, vaptans, hyponatremia, ADPKD, biopsy

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Next Generation Sequencing and ADPKD

Abstract

Autosomal Dominant Polycistic Kidney Disease (ADPKD) is the most common inherited genetic disorder in the word, caused by mutations in PKD1 gene in 85% of cases and PKD 2 gene in the remaining 15%. Although diagnosis is usually based on ultrasound, MRI and CT scans, in some cases genetic testing is necessary, for example, in patients with atypical phenotype or with a negative family history, or in cases of donation from relatives. The presence of pseudogenes in PKD1, the size of the gene, the costs of the Sanger sequencing and genetic heterogeneity underlying kidney disease make genetic analysis particularly difficult to be performed.  Next Generation Sequencing (NGS) represents the last frontier of innovation among diagnostic tools for molecular diagnosis of inherited cystic kidney disease thanks to the ability to analyze several genes at the same time. In this regard, we have developed a NGS platform, called Nephroplex, with the aim of identifying variations in 115 genes responsible for numerous kidney diseases, including cystic and polycystic disease, achieving, overall, a target region of 338.8 kbps. The technology used for the enrichment is HaloPlex system, based on the digestion of genomic DNA with restriction enzymes and the capture of the regions of interest with specific hybridization probes. With our platform, we have analyzed 9 patients with clinical diagnosis of ADPKD. We have obtained a depth coverage of 100x for 96.5% of the target, while the region not covered accounted for only 3% of the region of interest. In 6 patients, we found causative mutations in the genes PKD1 and PKD2, achieving a detection rate of 66%. In conclusion, the NephroPlex platform has proved to be an excellent device for molecular diagnosis of kidney disease and could clarify the mechanisms underlying genetic heterogeneity observed in kidney disease

Keywords: ADPKD, Nephroplex, Autosomal dominant polycystic kidney disease, Next Generation Sequencing

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