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Background. Autosomal dominant medullary cystic kidney disease (ADMCKD) is an inherited, distinct, chronic, tubulointerstitial, cystic-type nephropathy, often described together with juvenile nephronophthisis as a single disease complex (NPH-MCD). However, since the recent localization of two genes responsible for ADMCKD, namely MCKD1 and MCKD2, ADMCKD has gained independent status. Unfortunately, there appears to be a distinct lack of up-to-date information in the currently available medical literature concerning worldwide patient and graft survival after renal transplantation in ADMCKD. This report is based on all 41 transplanted patients [19 suffering from autosomal dominant medullary cystic kidney disease type 1 (ADMCKD1) and 22 from other causes] who were referred for kidney transplantation from our centre in Pafos, Cyprus between 1976 and 2000. All patients had regular follow-up examinations. This report aims to present the results of kidney transplantation of the 19 ADMCKD1 patients and to compare them with those for the 22 non-ADMCKD patients. Methods. Patient and graft survival times in both groups were recorded, analysed and compared 1 and 5 years post-transplant. Patient and graft survival times were calculated according to the Kaplan-Meier method and some descriptive statistical comparisons were based on the χ2-test. Results. The 1 year patient and graft survival rates for ADMCKD1 (group A) were 100%, while the 5 year figures were 100% and 90%, respectively. For non-ADMCKD1 patients (group B) the 1 year figures were 95% for both parameters, while the 5 year figures were 93.3% for both parameters. There were no statistically significant differences in patient and graft survival times between the two groups. Conclusions. Kidney transplantation is the treatment of choice for patients suffering from ADMCKD, with an excellent outcome and no specific complications. 18 2165 2169 Cited By :10

Familial glomerular hematuria(s) comprise a genetically heterogeneous group of conditions which include Alport Syndrome (AS) and thin basement membrane nephropathy (TBMN). Here we investigated 57 Greek-Cypriot families presenting glomerular microscopic hematuria (GMH), with or without proteinuria or chronic kidney function decline, but excluded classical AS. We specifically searched the COL4A3/A4 genes and identified 8 heterozygous mutations in 16 families (28,1%). Eight non-related families featured the founder mutation COL4A3-p.(G1334E). Renal biopsies from 8 patients showed TBMN and focal segmental glomerulosclerosis (FSGS). Ten patients (11.5%) reached end-stage kidney disease (ESKD) at ages ranging from 37-69-yo (mean 50,1-yo). Next generation sequencing of the patients who progressed to ESKD failed to reveal a second mutation in any of the COL4A3/A4/A5 genes, supporting that true heterozygosity for COL4A3/A4 mutations predisposes to CRF/ESKD. Although this could be viewed as a milder and late-onset form of autosomal dominant AS, we had no evidence of ultrastructural features or extrarenal manifestations that would justify this diagnosis. Functional studies in cultured podocytes transfected with wild type or mutant COL4A3 chains showed retention of mutant collagens and differential activation of the unfolded protein response (UPR) cascade. This signifies the potential role of the UPR cascade in modulating the final phenotype in patients with collagen IV nephropathies. © 2014 Papazachariou et al. 9 12 Cited By :13

There is a group of inherited cystic nephropathies that are characterized by juvenile onset recessive inheritance (familial juvenile nephronophthisis, FJN) or by adult onset dominant inheritance (medullary cystic disease, MCD) and share similar clinico-pathological presentation to the extent that they are usually grouped together under the term FJN/MCD complex. The main symptoms consist of renal cyst formation in the medulla or the corticomedullary junction and salt wasting. Although earlier reports had suggested that one single gene may be responsible for this pathology, recent reports have shown that the FJN complex itself comprises a genetically heterogeneous group. Here we are presenting two large Cypriot families that segregate autosomal dominant medullary cystic kidney disease (ADMCKD) with hyperuricemia and gout and with very late age of onset (mean 62.2 and 51.5 years). We performed DNA linkage mapping using highly polymorphic microsatellite markers and found linkage to marker locus D1S1595 at 1q21 with a two-point lod score of 6.45 at θ = 0.00. Analysis of haplotypes and of critical recombinants enabled confinement of the disease locus within an ~ 8 cM region between marker loci D1S498 and D1S2125. FISH mapping with a large P1 clone confirmed the physical localization within 1q21. The two families share the same disease haplotype, thus suggesting their relationship through a common ancestor and the possible existence of a single ADMCKD-causing mutation within these families. To our knowledge this is the first genetic locus identified to cause FJN/MCD pathology of the dominant adult type. 7 905 911 Cited By :99

The X-linked Alport syndrome (ATS) is caused by mutations in COL4A5 and exhibits a widely variable expression. Usually ATS is heralded with continuous microhematuria which rapidly progresses to proteinuria, hypertension and chronic or end-stage renal disease (ESRD) by adolescence, frequently accompanied by sensorineural deafness and ocular complications. Milder forms of ATS also exist. We studied 42 patients (19M, 23F) of nine Hellenic families suspected clinically of X-linked ATS who presented with marked phenotypic heterogeneity. We identified mutations in COL4A5 in six families. Two males with nonsense mutation E228X reached ESRD by ages 14 and 18. Frameshift mutation 2946delT followed the same course with early onset renal involvement and deafness. However, two males with the milder missense mutation G624D, reached ESRD after 39 years and one patient showed thin basement membrane nephropathy (TBMN). Another 5/8 affected males with missense mutation P628L also developed ESRD between 30 and 57 years, while three exhibit only mild chronic renal failure (CRF). The data support previous findings that certain mutations are associated with milder phenotypes and confirm that mutation G624D may be expressed as TBMN with familial hematuria. Similar conclusions apply for missense mutation P628L. Interestingly, mutations G624D and P628L are near the 12th natural interruption of COL4A5 triple helical domain, which may explain the milder phenotype. © 2011 John Wiley & Sons A/S. 81 240 248

Autosomal dominant medullary cystic kidney disease (ADMCKD) is an adult-onset heterogeneous genetic nephropathy characterized by salt wasting and end-stage renal failure. The gene responsible for ADMCKD-1 was mapped on chromosome 1 q21 and it is flanked proximally by marker D1S498 and distally by D1S2125, encompassing a region of ∼8 CM. Within this region there are a large number of transcribed genes including NPR1 that encodes the atrial natriuretic peptide receptor 1. This receptor plays a crucial role in regulation of blood pressure by facilitating salt excretion. Based on its function we hypothesized this gene as a reasonable candidate for the MCKD1 locus. DNA mutation screening was performed on the entire NPR1 gene-coding sequence and some of the 5′-UTR and 3′-UTR sequences. The samples investigated belonged to patients of five large ADMCKD-1 Cypriot families. The screening revealed two novel polymorphisms, one intragenic at amino acid position 939, which was occupied by either arginine or glutamine, and a second one located in the 3′-UTR, 29 nucleotides downstream of the NPR1 stop codon. The latter was a single nucleotide C insertion/deletion in a stretch of three or four Cs. No relationship was present between any allele of the two polymorphisms and the disease, as both alleles were observed in both affected and healthy subjects. In addition, no association was observed between the disease and another rare 8-bp deletion polymorphism at the 5′-UTR of NPR1 and the disease. Based on these findings it is unlikely that NPR1 is the same as the MCKD1 gene, although it is presently unknown whether it plays a disease modifying role. © 2001 Academic Press. 15 357 361 Cited By :4

Background. Autosomal-dominant medullary cystic kidney disease (ADMCKD), a hereditary chronic interstitial nephropathy, recently attracted attention because of the cloning or mapping of certain gene loci, namely NPHP1, NPHP2 and NPHP3 for familial juvenile nephronophthisis (NPH) and MCKD1 and MCKD2 for the adult form of medullary cystic kidney disease. Our aim was to present and discuss the clinical, biochemical, sonographic and histopathological findings in six large Cypriot families in whom molecular analysis has confirmed linkage to the MCKD1 locus on chromosome 1q21. Methods. The clinical, biochemical, sonographic and histopathological findings in 186 members of six large Cypriot families with ADMCKD-1 are presented. Creatinine clearance was calculated according to the Cockroft-Gault formula and was corrected to a body surface area (BSA) of 1.73 m2. DNA linkage analysis was performed with previously identified flanking polymorphic markers. Results. This disease is characterized by the absence of urinary findings in the vast majority of patients, leading to end-stage renal failure (ESRF) at a mean age of 53.7 years. Hypertension and hyperuricemia are common, especially in males, the former encountered more frequently in advanced chronic renal failure (CRF). Gout has been noted in a small percentage of male patients. Loss of urinary concentrating ability was not a prominent early feature of the disease, while severe natriuresis was observed in a few males toward ESRF. Renal cysts are mainly corticomedullary or medullary, and they are present in about 40.3% of patients and appear more frequently near ESRF. Conclusion. ADMCKD type 1 is a common cause of ESRF among our dialysis population. The disease is difficult to diagnose clinically, particularly in the early stage when renal cysts are not usually present, making them a weak diagnostic finding. A dominant pattern of inheritance and DNA linkage analysis are helpful in the diagnosis of this disease. 62 4 1385 1394 Cited By :37

Autosomal dominant medullary cystic kidney disease (ADMCKD synonym: medullary cystic disease, MCD) is an autosomal dominant kidney disorder, sharing morphological and clinical features with recessive juvenile nephronophthisis (NPH), such as reduced urinary concentration ability and multiple renal cysts at the corticomedullary junction. While in NPH end-stage renal disease (ESRD) occurs in adolescence, ADMCKD leads to ESRD in adulthood. Recently a gene locus for ADMCKD has been localized to chromosome 1q21 in two large Cypriot families. This prompted us to examine linkage in three ADMCKD-families, using the same set of polymorphic microsatellite markers spanning the critical region on chromosome 1q21. Haplotype analysis revealed that none of the three families showed linkage to this locus, thus demonstrating evidence for genetic locus heterogeneity. Additional linkage analysis studies need to be performed in order to identify further gene loci cosegregating with this autosomal dominant kidney disorder. 13 1955 1957 Cited By :25

We describe a large Cypriot family with an interstitial type of nephropathy, inherited as an autosomal dominant trait that led to end stage renal failure between 51 to 78 years of age (mean 62.2 years). Twenty-three people are known to be affected, but several younger relatives with normal renal function may remain undiagnosed because of the absence of precise clinical and laboratory diagnostic criteria. This nephropathy is associated with medullary renal cysts, hypertension, hyperuricemia, and gout. Several relatives have typical medullary cystic disease (MCD), while in the others the findings are compatible with this diagnosis. Due to the similarity of clinical and pathologic findings, earlier reports had suggested that MCD may be allelic to autosomal recessive familial juvenile nephronophthisis, which was mapped recently to chromosome band 2q13. Linkage analysis of the present family with a closely linked marker excluded linkage to the above locus. Linkage was also excluded to the PKD1 locus of adult polycystic kidney disease type 1, and up to 5 cM on either side, on chromosome 16. We suggest that because of the element of hyperuricemia and gout found in this family, although with reduced penetrance, it may represent a variant of autosomal dominant MCD of the adult type. This variability may be the result of allelic or locus heterogeneity. Molecular genetic approaches including linkage analysis on appropriate families will certainly assist in classifying such related genetically heterogeneous disorders. 77 149 154 Cited By :23