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Fabry disease or also called Anderson-Fabry disease (FD) is a rare disease caused by pathogenic variants in the GLA gene, located on the X chromosome. This gene is involved in the metabolism of glycosphingolipids and its pathogenic variants cause a deficit or absence of α-galactosidase A causing the deposition of globotriaosylceramide throughout the body. Females have a variable phenotypic expression and a better prognosis than males. This is due to the X chromosome inactivation phenomenon. We present a clinical case of Fabry disease in a female with predominantly renal involvement and demonstrate how the X chromosome inactivation phenomenon is tissue dependent, showing preferential inactivation of the mutated allele at the renal level. Resumen: La enfermedad de Fabry o también llamada de Anderson-Fabry (EF) es una enfermedad rara, causada por variantes patogénicas en el gen GLA, localizado en el cromosoma X. Este gen interviene en el metabolismo de los glucoesfingolípidos y variantes patogénicas en el mismo causan déficit o ausencia de la α-galactosidasa A ocasionando el depósito de globotriaosilceramida en todo el organismo. Las mujeres presentan una expresión fenotípica variable y de mejor pronóstico que los varones. Esto es debido al fenómeno de inactivación del cromosoma X. Presentamos un caso clínico de enfermedad de Fabry en una mujer con afectación predominantemente renal y demostramos cómo el fenómeno de la inactivación del cromosoma X es tejido dependiente, mostrando una inactivación preferencial del alelo mutado a nivel renal.

Resumen: La enfermedad de Fabry o también llamada de Anderson-Fabry (EF) es una enfermedad rara, causada por variantes patogénicas en el gen GLA, localizado en el cromosoma X. Este gen interviene en el metabolismo de los glucoesfingolípidos y variantes patogénicas en el mismo causan déficit o ausencia de la α-galactosidasa A, ocasionando el depósito de globotriaosilceramida en todo el organismo. Las mujeres presentan una expresión fenotípica variable y de mejor pronóstico que los varones. Esto es debido al fenómeno de inactivación del cromosoma X. Presentamos un caso clínico de enfermedad de Fabry en una mujer con afectación predominantemente renal y demostramos cómo el fenómeno de la inactivación del cromosoma X es tejido dependiente, mostrando una inactivación preferencial del alelo mutado a nivel renal. Abstract: Fabry disease or also called Anderson–Fabry disease (FD) is a rare disease caused by pathogenic variants in the GLA gene, located on the X chromosome. This gene is involved in the metabolism of glycosphingolipids and its pathogenic variants cause a deficit or absence of α-galactosidase A causing the deposition of globotriaosylceramide throughout the body. Females have a variable phenotypic expression and a better prognosis than males. This is due to the X chromosome inactivation phenomenon. We present a clinical case of Fabry disease in a female with predominantly renal involvement and demonstrate how the X chromosome inactivation phenomenon is tissue dependent, showing preferential inactivation of the mutated allele at the renal level.

Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent cause of genetic renal disease and accounts for 6–10% of patients on kidney replacement therapy (KRT).Very few prospective, randomized trials or clinical studies address the diagnosis and management of this relatively frequent disorder. No clinical guidelines are available to date. This is a revised consensus statement from the previous 2014 version, presenting the recommendations of the Spanish Working Group on Inherited Kidney Diseases, which were agreed to following a literature search and discussions. Levels of evidence mostly are C and D according to the Centre for Evidence-Based Medicine (University of Oxford). The recommendations relate to, among other topics, the use of imaging and genetic diagnosis, management of hypertension, pain, cyst infections and bleeding, extra-renal involvement including polycystic liver disease and cranial aneurysms, management of chronic kidney disease (CKD) and KRT and management of children with ADPKD. Recommendations on specific ADPKD therapies are provided as well as the recommendation to assess rapid progression. Resumen: La poliquístosis renal autosómica dominante (PQRAD) es la causa más frecuente de nefropatía genética y representa entre 6 a 10% de los pacientes en terapia de reemplazo renal (TRR).Muy pocos ensayos prospectivos, aleatorizados o estudios clínicos abordan el diagnóstico y el tratamiento de este trastorno relativamente frecuente. No hay guías clínicas disponibles hasta la fecha. Esta es un docuemento de consenso revisada de la versión anterior de 2014, que presenta las recomendaciones del Grupo de Trabajo Español de Enfermedades Renales Hereditarias, acordadas tras la búsqueda bibliográfica y discusiones. Los niveles de evidencia en su mayoría son C y D según el Centro de Medicina Basada en Evidencia (Universidad de Oxford). Las recomendaciones se relacionan, entre otros temas, con el uso de diagnóstico por imágenes y genético, el manejo de la hipertensión, el dolor, las infecciones y el sangrado quístico, la afectación extrarrenal, incluida la enfermedad poliquística hepática y los aneurismas craneales, el manejo de la enfermedad renal crónica (ERC) y el TRR asi como el seguimiento de niños con PQRAD. Se proporcionan recomendaciones sobre terapias específicas para la PQRAD, así como la recomendación para evaluar la rápida progresión.

Resumen: La poliquistosis renal autosómica dominante (PQRAD) es la causa más frecuente de nefropatía genética y representa entre el 6 y el 10% de los pacientes en terapia de reemplazo renal (TRR).Muy pocos ensayos prospectivos, aleatorizados o estudios clínicos abordan el diagnóstico y el tratamiento de este trastorno relativamente frecuente. No hay guías clínicas disponibles hasta la fecha. Este es un documento de consenso revisada de la versión anterior del 2014, que presenta las recomendaciones del Grupo de Trabajo Español de Enfermedades Renales Hereditarias, acordadas tras la búsqueda bibliográfica y discusiones. Los niveles de evidencia en su mayoría son C y D según el Centro de Medicina Basada en Evidencia (Universidad de Oxford). Las recomendaciones se relacionan, entre otros temas, con el uso de diagnóstico por imágenes y genético, el manejo de la hipertensión, el dolor, las infecciones y el sangrado quístico, la afectación extrarrenal, incluida la enfermedad poliquística hepática y los aneurismas craneales, el manejo de la enfermedad renal crónica y el TRR, así como el seguimiento de niños con PQRAD. Se proporcionan recomendaciones sobre terapias específicas para la PQRAD, así como la recomendación para evaluar la rápida progresión. Abstract: Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent cause of genetic renal disease and accounts for 6–10% of patients on kidney replacement therapy (KRT).Very few prospective, randomized trials or clinical studies address the diagnosis and management of this relatively frequent disorder. No clinical guidelines are available to date. This is a revised consensus statement from the previous 2014 version, presenting the recommendations of the Spanish Working Group on Inherited Kidney Diseases, which were agreed to following a literature search and discussions. Levels of evidence mostly are C and D according to the Centre for Evidence-Based Medicine (University of Oxford). The recommendations relate to, among other topics, the use of imaging and genetic diagnosis, management of hypertension, pain, cyst infections and bleeding, extra-renal involvement including polycystic liver disease and cranial aneurysms, management of chronic kidney disease and KRT and management of children with ADPKD. Recommendations on specific ADPKD therapies are provided as well as the recommendation to assess rapid progression.

Membranous nephropathy (MN) is a rare autoimmune disease of podocyte-directed antibodies, such as anti-phospholipase A2 receptor. Here, the authors report a genome-wide association study for MN and identify two previously unreported loci encompassing the NFKB1 and IRF4 genes and additional ancestry-specific effects.

Background. Fabry disease (FD) is an X-linked lysosomal storage disorder caused by pathogenic variants of the GLA gene. Heterozygous female patients may show much more variability in clinical manifestations, ranging from asymptomatic to full-blown disease. Because of this heterogeneous clinical picture in women, the diagnosis of FD has typically been delayed for more than a decade, and the optimal time to initiate treatment remains controversial. Case Presentation. Here, we present two unrelated female patients diagnosed with FD harbouring the same pathogenic GLA variant. We discuss the implications of initiating specific therapy at different stages of the disease, with and without organ involvement (early versus late therapeutic intervention). Conclusions. These clinical cases suggest that initiating specific treatment at an earlier age in women with FD may prevent organ involvement and associated clinical events.

Abstract Background Galloway-Mowat syndrome (GAMOS) is a rare autosomal recessive disorder characterized by early-onset nephrotic syndrome and microcephaly with brain anomalies. WDR73 pathogenic variants were described as the first genetic cause of GAMOS and, very recently, four novel causative genes, OSGEP, LAGE3, TP53RK, and TPRKB, have been identified. Case presentation We present the clinical and genetic characteristics of two unrelated infants with clinical suspicion of GAMOS who were born from consanguineous parents. Both patients showed a similar clinical presentation, with early-onset nephrotic syndrome, microcephaly, brain atrophy, developmental delay, axial hypotonia, and early fatality. We identified two novel likely disease-causing variants in the OSGEP gene. These two cases, in conjunction with the findings of a literature review, indicate that OSGEP pathogenic variants are associated with an earlier onset of nephrotic syndrome and shorter life expectancy than WDR73 pathogenic variants. Conclusions Our findings expand the spectrum of pathogenic variants in the OSGEP gene and, taken in conjunction with the results of the literature review, suggest that the OSGEP gene should be considered the main known monogenic cause of GAMOS. Early genetic diagnosis of GAMOS is of paramount importance for genetic counseling and family planning.

Resumen: Las enfermedades relacionadas con mutaciones del gen MYH9 son un grupo de patologías genéticas raras. Su herencia sigue un patrón autosómico dominante en donde el gen MYH9, codifica la cadena pesada de la miosina IIA no muscular que se expresa en diferentes tejidos pero especialmente en los podocitos y en las células mesangiales. Este trastorno se caracteriza por la presencia de macrotrombocitopenia, inclusiones leucocitarias y un riesgo variable de desarrollar insuficiencia renal, hipoacusia y cataratas en edad juvenil o adulta. Describimos el caso de una mujer de 27 años, de raza caucásica, diagnosticada inicialmente de púrpura trombocitopénica idiopática. Tras una detallada historia familiar y el desarrollo de síntomas clínicos posteriores con afectación renal e hipoacusia, se le realizó un estudio genético que nos permitió el diagnóstico de nefropatía asociada a la mutación en el gen MYH9. Este caso destaca el retraso del diagnóstico y la utilidad del estudio genético en pacientes con enfermedades muy poco frecuentes. Se procede a la revisión de la enfermedad en este artículo. Abstract: MYH9 related diseases are caused by mutations in the MYH9 gene and constitute a rare group of genetic entities. Its inheritance follows an autosomal dominant pattern. The MYH9 gene, encodes the nonmuscle myosin heavy chain IIA, expressed in different tissues and especially in podocytes and mesangial cells. The disorder is characterized by the presence of macrothrombocytopenia, leukocyte inclusions and a variable risk of developing renal failure, hearing loss and early-onset cataracts. We describe the case of a 27-year-old Caucasian woman, diagnosed initially with idiopathic thrombocytopenic purpura. After a detailed family history and the appearance of renal involvement and hearing loss, genetic testing allowed to make the diagnosis of nephropathy associated with MYH9 mutation. This case is an example of the delayed diagnosis of uncommon diseases and highlights the usefulness genetic testing. A review of the disease is provided. Palabras clave: Nefropatía MYH9, Hipoacusia, Trombocitopenia, Síndrome de Alport, Síndrome de Epstein, Anomalía de May-Hegglin, Sindrome de Sebastián, Keywords: MYH9 nephropathy, Hearing loss, Thrombocytopenia, Alport syndrome, Epstein syndrome, May-Hegglin anomaly

MYH9 related diseases are caused by mutations in the MYH9 gene and constitute a rare group of genetic entities. Its inheritance follows an autosomal dominant pattern. The MYH9 gene, encodes the nonmuscle myosin heavy chain IIA, expressed in different tissues and especially in podocytes and mesangial cells. The disorder is characterized by the presence of macrothrombocytopenia, leukocyte inclusions and a variable risk of developing renal failure, hearing loss and early-onset cataracts. We describe the case of a 27-year-old Caucasian woman, diagnosed initially with idiopathic thrombocytopenic purpura. After a detailed family history and the appearance of renal involvement and hearing loss, genetic testing allowed to make the diagnosis of nephropathy associated with MYH9 mutation. This case is an example of the delayed diagnosis of uncommon diseases and highlights the usefulness genetic testing. A review of the disease is provided. Resumen: Las enfermedades relacionadas con mutaciones del gen MYH9 son un grupo de patologías genéticas raras. Su herencia sigue un patrón autosómico dominante en donde el gen MYH9, codifica la cadena pesada de la miosina IIA no muscular que se expresa en diferentes tejidos pero especialmente en los podocitos y en las células mesangiales. Este trastorno se caracteriza por la presencia de macrotrombocitopenia, inclusiones leucocitarias y un riesgo variable de desarrollar insuficiencia renal, hipoacusia y cataratas en edad juvenil o adulta. Describimos el caso de una mujer de 27 años, de raza caucásica, diagnosticada inicialmente de púrpura trombocitopénica idiopática. Tras una detallada historia familiar y el desarrollo de síntomas clínicos posteriores con afectación renal e hipoacusia, se le realizó un estudio genético que nos permitió el diagnóstico de nefropatía asociada a la mutación en el gen MYH9. Este caso destaca el retraso del diagnóstico y la utilidad del estudio genético en pacientes con enfermedades muy poco frecuentes. Se procede a la revisión de la enfermedad en este artículo. Keywords: MYH9 nephropathy, Hearing loss, Thrombocytopenia, Alport syndrome, Epstein syndrome, May-Hegglin anomaly, Palabras clave: Nefropatía MYH9, Hipoacusia, Trombocitopenia, Síndrome de Alport, Síndrome de Epstein, Anomalía de May-Hegglin, Sindrome de Sebastián

A skin biopsy was obtained from a 25-year-old female patient with autosomal recessive Alport syndrome (ARAS) with the homozygous COL4A3 mutation c.345delG, p.(P166Lfs*37). Dermal fibroblasts were derived and reprogrammed by nucleofection with episomal plasmids carrying OCT3/4, SOX2, KLF4 LIN28, L-MYC and p53shRNA. The generated induced Pluripotent Stem Cell (iPSC) clone AS FiPS1 Ep6F-2 was free of genomically integrated reprogramming genes, had the specific homozygous mutation, a stable karyotype, expressed pluripotency markers and generated embryoid bodies which were differentiated towards the three germ layers in vitro. This iPSC line offers a useful resource to study Alport syndrome pathomechanisms and drug testing.

Skin biopsies were obtained from two male patients with X-linked Alport syndrome (XLAS) with hemizygous COL4A5 mutations in exon 41 or exon 46. Dermal fibroblasts were extracted and reprogrammed by nucleofection with episomal plasmids carrying OCT3/4, SOX2, KLF4 LIN28, L-MYC and p53 shRNA. The generated induced Pluripotent Stem Cell (iPSC) lines AS-FiPS2-Ep6F-28 and AS-FiPS3-Ep6F-9 were free of genomically integrated reprogramming genes, had the specific mutations, a stable karyotype, expressed pluripotency markers and generated embryoid bodies which were differentiated towards the three germ layers in vitro. These iPSC lines offer a useful resource to study Alport syndrome pathomechanisms and drug testing.

En los últimos años ha habido una reclasificación de las nefropatías tubulointersticiales de base genética. Los antiguos conceptos de nefronoptisis o enfermedad quística medular han sido reordenados con base en el hallazgo de nuevos genes. Las guías KDIGO del 2015 proponen una unificación de terminología, unos criterios diagnósticos y de seguimiento. Hasta el momento se han descrito 4 genes causantes de la nefropatía tubulointersticial autosómica dominante: MUC1, UMOD, HNF1B y REN. Aunque la mutación en cada uno de los genes produce unos rasgos diferenciales en la forma de presentación, todas las formas tienen en común el progresivo daño túbulo-intersticial y la fibrosis renal. En este artículo, se pretende una revisión de las guías, de la literatura y ofrecer unas recomendaciones prácticas para el manejo de esta enfermedad.

In recent years there has been a reclassification of hereditary tubulointerstitial renal diseases. The old concepts of nephronoptisis or medullary cystic disease have been reordered based on the discovery of new genes. The 2015 KDIGO guidelines proposed a unification of terminology, diagnostic criteria and monitoring. So far 4 genes causing autosomal dominant tubulointerstitial kidney disease have been described: MUC1, UMOD, HNF1B and REN. Although the mutation in each of them causes distinctive features in how they present, all have in common the progressive tubulointerstitial damage and renal fibrosis. In this article, we present a review of the guidelines and the literature, and some practical recommendations for dealing with this disease.

We report the case of a 32-year-old male diagnosed with TSC2/PKD1 contiguous gene syndrome, presenting with tuberous sclerosis complex (TSC) and autosomal dominant polycystic kidney disease simultaneously. He progressed to end-stage renal disease and received a kidney transplant at the age of 12. The native kidneys presented angiomyolipomas (AML), which are common benign tumours in patients with TSC. Seventeen years after transplantation, he presented with abdominal pain, anaemia and a retroperitoneal haematoma, the latter caused by renal AML bleeding. Selective embolisation was performed. Our patient could have benefited from the administration of mTOR inhibitors at transplant. This therapy is immunosuppressive and reduces the size of benign tumours in TSC as well as the risk of rupture and bleeding. This patient did not receive mTOR inhibitors at the time of the transplant because the relationship between mTOR inhibitors and TSC was unknown at that time. This case confirms the persistent risk of renal AML bleeding for both transplanted patients and patients on dialysis. As a result, we would recommend routine check-ups of native kidneys and nephrectomy assessment.

Presentamos el caso de un varón de 32 años, con síndrome de genes contiguos TSC2/PKD1, que le ocasiona esclerosis tuberosa (ET) y poliquistosis renal autosómica dominante simultáneamente. Evolucionó a enfermedad renal terminal y se realizó trasplante renal a los 12 años. Los riñones presentaban angiomiolipomas (AML), que son tumores benignos frecuentes en pacientes con ET. A los 17 años postrasplante, presentó un cuadro de dolor abdominal, anemización y hematoma retroperitoneal. Dicho hematoma se produjo por el sangrado de los AML. Como tratamiento se realizó embolización selectiva. Nuestro paciente podría haberse beneficiado en el momento del trasplante renal del tratamiento con inhibidores de mTOR. Este fármaco actúa como inmunosupresor y reductor tumoral en la ET, al disminuir el riesgo de rotura y hemorragia. En este paciente no se administró porque cuando se trasplantó no se conocía la relación de los inhibidores de mTOR con la ET. Este caso confirma que, a pesar de tratarse de pacientes trasplantados o en diálisis, el riesgo de sangrado por los AML persiste, por lo cual se propone realizar controles periódicos de los riñones propios y valorar la nefrectomía.

Alport syndrome results from mutations in the COL4A5 (X-linked) or COL4A3/COL4A4 (recessive) genes. This study examined 754 previously- unpublished variants in these genes from individuals referred for genetic testing in 12 accredited diagnostic laboratories worldwide, in addition to all published COL4A5, COL4A3 and COL4A4 variants in the LOVD databases. It also determined genotype-phenotype correlations for variants where clinical data were available. Individuals were referred for genetic testing where Alport syndrome was suspected clinically or on biopsy (renal failure, hearing loss, retinopathy, lamellated glomerular basement membrane), variant pathogenicity was assessed using currently-accepted criteria, and variants were examined for gene location, and age at renal failure onset. Results were compared using Fisher's exact test (DNA Stata). Altogether 754 new DNA variants were identified, an increase of 25%, predominantly in people of European background. Of the 1168 COL4A5 variants, 504 (43%) were missense mutations, 273 (23%) splicing variants, 73 (6%) nonsense mutations, 169 (14%) short deletions and 76 (7%) complex or large deletions. Only 135 of the 432 Gly residues in the collagenous sequence were substituted (31%), which means that fewer than 10% of all possible variants have been identified. Both missense and nonsense mutations in COL4A5 were not randomly distributed but more common at the 70 CpG sequences (pAla substitutions were underrepresented in all three genes (p< 0.0001) probably because of an association with a milder phenotype. The average age at end-stage renal failure was the same for all mutations in COL4A5 (24.4 ±7.8 years), COL4A3 (23.3 ± 9.3) and COL4A4 (25.4 ± 10.3) (COL4A5 and COL4A3, p = 0.45; COL4A5 and COL4A4, p = 0.55; COL4A3 and COL4A4, p = 0.41). For COL4A5, renal failure occurred sooner with non-missense than missense variants (p

INTRODUCTION:Spermatogenesis is a highly complex process involving several thousand genes, only a minority of which have been studied in infertile men. In a previous study, we identified a number of Copy Number Variants (CNVs) by high-resolution array-Comparative Genomic Hybridization (a-CGH) analysis of the X chromosome, including 16 patient-specific X chromosome-linked gains. Of these, five gains (DUP1A, DUP5, DUP20, DUP26 and DUP40) were selected for further analysis to evaluate their clinical significance. MATERIALS AND METHODS:The copy number state of the five selected loci was analyzed by quantitative-PCR on a total of 276 idiopathic infertile patients and 327 controls in a conventional case-control setting (199 subjects belonged to the previous a-CGH study). For one interesting locus (intersecting DUP1A) additional 338 subjects were analyzed. RESULTS AND DISCUSSION:All gains were confirmed as patient-specific and the difference in duplication load between patients and controls is significant (p = 1.65 × 10(-4)). Two of the CNVs are private variants, whereas 3 are found recurrently in patients and none of the controls. These CNVs include, or are in close proximity to, genes with testis-specific expression. DUP1A, mapping to the PAR1, is found at the highest frequency (1.4%) that was significantly different from controls (0%) (p = 0.047 after Bonferroni correction). Two mechanisms are proposed by which DUP1A may cause spermatogenic failure: i) by affecting the correct regulation of a gene with potential role in spermatogenesis; ii) by disturbing recombination between PAR1 regions during meiosis. This study allowed the identification of novel spermatogenesis candidate genes linked to the 5 CNVs and the discovery of the first recurrent, X-linked gain with potential clinical relevance.

The role of CNVs in male infertility is poorly defined, and only those linked to the Y chromosome have been the object of extensive research. Although it has been predicted that the X chromosome is also enriched in spermatogenesis genes, no clinically relevant gene mutations have been identified so far.In order to advance our understanding of the role of X-linked genetic factors in male infertility, we applied high resolution X chromosome specific array-CGH in 199 men with different sperm count followed by the analysis of selected, patient-specific deletions in large groups of cases and normozoospermic controls.We identified 73 CNVs, among which 55 are novel, providing the largest collection of X-linked CNVs in relation to spermatogenesis. We found 12 patient-specific deletions with potential clinical implication. Cancer Testis Antigen gene family members were the most frequently affected genes, and represent new genetic targets in relationship with altered spermatogenesis. One of the most relevant findings of our study is the significantly higher global burden of deletions in patients compared to controls due to an excessive rate of deletions/person (0.57 versus 0.21, respectively; p = 8.785×10(-6)) and to a higher mean sequence loss/person (11.79 Kb and 8.13 Kb, respectively; p = 3.435×10(-4)).By the analysis of the X chromosome at the highest resolution available to date, in a large group of subjects with known sperm count we observed a deletion burden in relation to spermatogenic impairment and the lack of highly recurrent deletions on the X chromosome. We identified a number of potentially important patient-specific CNVs and candidate spermatogenesis genes, which represent novel targets for future investigations.

Background. Hypertension induced by cyclosporine is associated with renal sodium and water retention. Using immunoblotting of kidney homogenates, we investigated the regulation of sodium and water transport proteins in a rat model of cyclosporine-induced hypertension. Methods. Rats were treated with cyclosporine (25 mg/kg/day intraperitoneally) during 7 days. Control rats received vehicle. Results. Cyclosporine-treated rats had an increase in blood pressure with a decrease in renal sodium excretion compared with control rats. There were no differences either in sodium intake or in plasma creatinine levels between the two groups of rats. These data suggest that the decrease in sodium excretion in the cyclosporine-treated rats was due to an increase in renal sodium absorption. The densitometric analysis of the renal immunoblot showed an increase in the Na-K-2Cl cotransporter of the loop of Henle (NKCC2) in cyclosporine-treated rats (178% ± 36) compared with control rats (100% ± 18; P < 0.05*). This protein rise was associated with an increase in the NKCC2 mRNA pointing to a transcriptional regulation of this sodium transporter. There were no statistically significant changes in the sodium proton exchange (NHE-3) of the proximal tubule although in this renal segment, aquaporin-1 was increased in cyclosporine-treated rats compared with control rats (control 100% ± 6 vs cyclosporine 119% ± 6; P < 0.05*). Conclusions. Our results pointed to the thick ascending limb of the loop of Henle as an important site of sodium retention in cyclosporine-induced hypertension. This data may have potential clinical implications for the treatment of hypertension induced by cyclosporine. [ABSTRACT FROM AUTHOR]

Background. Autosomal dominant polycystic kidney disease (ADPKD) is a systemic disorder with a wide spectrum of renal involvement. Differences in the age at onset of end-stage renal disease (ESRD) are partially explained by the genetic heterogeneity of the disease but intrafamilial variability remains to be explained. Modifier genes may play a role in disease severity. Methods. A total of 355 PKD1 patients from 131 families belonging to three different European centres were analysed. According to the age at onset of ESRD patients were classified into two groups: early and late onset. Two different cut-offs were used. Based on literature, early onset was firstly considered when ESRD was reached before 40 years of age and late onset after 60 years of age. Secondly, according to the bimodal distribution of age at onset of ESRD in our population we established two groups with similar variability and the cut-offs were assigned before 48 years of age and after 56 years of age. These groups of patients were then analysed by two different complementary perspectives: (i) using ESRD onset as a quantitative trait when performing survival analysis and Cox regression analysis, and (ii) considering it a qualitative trait. The candidate genes (and polymorphisms) studied were the following: NOS3 (T-786C and E298D), BDKRB1 (−699 G > C), BDKRB2 (R14C), TGFB1 (−509 C > T, R25P and L10P), ACE (I/D), EGFR (IVS1CA) and PKD2 (−9780 G > A, −718 A > G and 83 C > G). Results. The results disclosed that the ACE polymorphism had a slight influence on the age of onset of ESRD in ADPKD patients and the NOS3 and BDKBR1 polymorphisms showed a very slight involvement in renal outcome. Conclusions. Our results discard the most prominent functional genes suggested to date, to have a major effect on ADPKD progression in this cohort. Genes strongly implicated in disease severity are yet to be identified. The description of such genes would allow us to establish a prognosis for ADPKD and eventually to develop therapeutic interventions. [ABSTRACT FROM AUTHOR]