Pheochromocytoma-Paraganglioma Syndrome: A Multiform Disease with Different Genotype and Phenotype Features.

Pheochromocytoma and paraganglioma (PPGL) are rare tumors derived from the adrenal medulla and extra-adrenal chromaffin cells. Diagnosis is often challenging due to the great variability in clinical presentation; the complexity of management due to the dangerous effects of catecholamine excess and the potentially malignant behavior require in-depth knowledge of the pathology and multidisciplinary management. Nowadays, diagnostic ability has certainly improved and guidelines and consensus documents for treatment and follow-up are available. A major impulse to the development of this knowledge has come from the new findings on the genetic and molecular characteristics of PPGLs. Germline mutation in susceptibility genes is detected in 40% of subjects, with a mutation frequency of 10-12% also in patients with sporadic presentation and genetic testing should be incorporated within clinical care. PPGL susceptibility genes include "old genes" associated with Neurofibromatosis type 1 (NF1 gene), Von Hippel Lindau syndrome (VHL gene) and Multiple Endocrine Neoplasia type 2 syndrome (RET gene), the family of SDHx genes (SDHA, SDHB, SDHC, SDHD, SDHAF2), and genes less frequently involved such as TMEM, MAX, and FH. Each gene has a different risk of relapse, malignancy, and other organ involvement; for mutation carriers, affected or asymptomatic, it is possible to define a tailored long-life surveillance program according to the gene involved. In addition, molecular characterization of the tumor has allowed the identification of somatic mutations in other driver genes, bringing to 70% the PPGLs for which we know the mechanisms of tumorigenesis. This has expanded the catalog of tumor driver genes, which are identifiable in up to 70% of patients Integrated genomic and transcriptomic data over the last 10 years have revealed three distinct major molecular signatures, triggered by pathogenic variants in susceptibility genes and characterized by the activation of a specific oncogenic signaling: the pseudo hypoxic, the kinase, and the Wnt signaling pathways. These molecular clusters show a different biochemical phenotype and clinical behavior; they may also represent the prerequisite for implementing customized therapy and follow-up.

Eight-Fold Increased COVID-19 Mortality in Autosomal Dominant Tubulointerstitial Kidney Disease due to MUC1 Mutations: An Observational Study.

Background: MUC1 and UMOD pathogenic variants cause autosomal dominant tubulointerstitial kidney disease (ADTKD). MUC1 is expressed in kidney, nasal mucosa and respiratory tract, while UMOD is expressed only in kidney. Due to haplo-insufficiency ADTKD- MUC1 patients produce approximately 50% of normal mucin-1. Methods: To determine whether decreased mucin-1 production was associated with an increased COVID-19 risk, we sent a survey to members of an ADTKD registry in September 2021, after the initial, severe wave of COVID-19. We linked results to previously obtained ADTKD genotype and plasma CA15-3 (mucin-1) levels and created a longitudinal registry of COVID-19 related deaths. Results: Surveys were emailed to 637 individuals, with responses from 89 ADTKD- MUC1 and 132 ADTKD- UMOD individuals. 19/83 (23%) ADTKD- MUC1 survey respondents reported a prior COVID-19 infection vs. 14/125 (11%) ADTKD- UMOD respondents (odds ratio (OR) 2.35 (95%CI 1.60-3.11, P = 0.0260). Including additional familial cases reported from survey respondents, 10/41 (24%) ADTKD- MUC1 individuals died of COVID-19 vs. 1/30 (3%) with ADTKD- UMOD , with OR 9.21 (95%CI 1.22-69.32), P = 0.03. The mean plasma mucin-1 level prior to infection in 14 infected and 27 uninfected ADTKD- MUC1 individuals was 7.06±4.12 vs. 10.21±4.02 U/mL ( P = 0.035). Over three years duration, our longitudinal registry identified 19 COVID-19 deaths in 360 ADTKD- MUC1 individuals (5%) vs. 3 deaths in 478 ADTKD- UMOD individuals (0.6%) ( P = 0.0007). Multivariate logistic regression revealed the following odds ratios (95% confidence interval) for COVID-19 deaths: ADTKD- MUC1 8.4 (2.9-29.5), kidney transplant 5.5 (1.6-9.1), body mass index (kg/m 2 ) 1.1 (1.0-1.2), age (y) 1.04 (1.0-1.1). Conclusions: Individuals with ADTKD- MUC1 are at an eight-fold increased risk of COVID-19 mortality vs. ADTKD- UMOD individuals. Haplo-insufficient production of mucin-1 may be responsible.

Clinical Significance of the Cystic Phenotype in Alport Syndrome.

RATIONALE & OBJECTIVE: Alport syndrome (AS) is the most common genetic glomerular disease caused by mutations that affect type IV collagen. However, the clinical characteristics and significance of AS with kidney cysts are not well defined. This study investigated the prevalence and clinical significance of cystic kidney phenotype in AS. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: One hundred-eight patients with AS and a comparison cohort of 79 patients with IgA nephropathy (IgAN). Clinical, genetic, and imaging data were collected from medical records. EXPOSURE: Cystic kidney phenotype evaluated by ultrasonography and defined as the presence of≥3 cysts in each kidney; demographic characteristics and estimated glomerular filtration rate (eGFR) at disease onset. OUTCOME: Cystic kidney phenotype in the AS and IgAN cohorts; time to chronic kidney disease (CKD) stage 3b and longitudinal changes in eGFR in the AS cohort. ANALYTICAL APPROACH: Logistic regression analysis to test independent strengths of associations of clinical/demographic features with the binary outcome of cystic phenotype. Survival analysis for the outcome of reaching CKD stage 3b and linear mixed models for changes in eGFR over time in the AS cohort. RESULTS: We studied 108 patients with AS; 76 (70%) had a genetic diagnosis. Autosomal dominant AS was prevalent, accounting for 68% of patients with a genetic diagnosis. Cystic kidney phenotype was observed in 38% of patients with AS and was associated with normal-sized kidneys in all but 3 patients, who showed increased total kidney volume, mimicking autosomal dominant polycystic kidney disease. The prevalence of cystic kidney phenotype was significantly higher in patients with AS when compared with the group of patients with IgAN (42% vs 19%; P=0.002). Patients with the cystic kidney phenotype were older and had more marked reduction in eGFR than patients without cystic changes. Among patients with AS, the cystic phenotype was associated with older age and a faster decline eGFR. LIMITATIONS: Retrospective, single-center study. CONCLUSIONS: Cystic kidney phenotype is a common finding in AS. The cystic kidney phenotype is a common finding in AS, suggesting a possible role in cystogenesis for the genetic variants that cause this disease. PLAIN-LANGUAGE SUMMARY: Hematuria is the classic renal presentation of Alport syndrome (AS), a hereditary glomerulopathy caused by pathogenic variants of the COL4A3-5 genes. An atypical kidney cystic phenotype has been rarely reported in individuals with these variants. To determine the prevalence of kidney cysts, we performed abdominal ultrasonography in a large group of patients with AS and a comparison group of patients with another glomerular kidney disease, IgA nephropathy (IgAN). Multiple kidney cysts, usually with normal kidney volume, were found in 38% of patients with AS. A few patients' kidney volumes were large enough to mimic a different hereditary cystic kidney disease, autosomal dominant polycystic kidney disease. The overall prevalence of kidney cysts in AS was more than double that observed in the well-matched comparison group with IgAN. These findings emphasize the high prevalence of cystic kidney phenotype in AS, suggesting a likely association between the genetic variants that cause this disease and the development of kidney cysts.

Monoallelic pathogenic IFT140 variants are a common cause of autosomal dominant polycystic kidney disease-spectrum phenotype.

Background: Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disorder, characterized by development and enlargement of kidney cysts, eventually leading to end-stage kidney disease (ESKD). Pathogenic variants in the PKD1 and PKD2 genes are the major cause of ADPKD; additional rare variants in the GANAB, DNAJB11, ALG5 and ALG9 genes have been found in a minority of ADPKD patients. More recently, a significant number of ADPKD families have been linked to monoallelic variants in the IFT140 gene. Methods: In this retrospective study, we tested the prevalence of the known causative genes of ADPKD-spectrum phenotype, including the PKD1, PKD2, GANAB, DNAJB11, ALG5, ALG and IFT140 genes, in a cohort of 129 ADPKD patients who consecutively underwent genetic testing in a single centre in Italy. Genetic testing utilized a combination of targeted next-generation sequencing, long-range polymerase chain reaction, Sanger sequencing and multiplex ligation-dependent probe amplification. Clinical evaluation was conducted through renal function testing and imaging features, including ultrasonography, computer tomography and magnetic resonance imaging. Results: Of the 129 enrolled patients, 86 (66.7%) had pathogenic variants in PKD1 and 28 (21.7%) in PKD2, loss of function pathogenic variants in the IFT140 gene were found in 3 unrelated patients (2.3%), no pathogenic variants were found in other ADPKD genes and 12 patients (9.3%) remained genetically unresolved (ADPKD-GUR). Familial clinical and genetic screening of the index patients with ADPKD due to an IFT140 pathogenic variant (ADPKD-IFT140) allowed identification of eight additional affected relatives. In the 11 ADPKD-IFT140 patients, the renal phenotype was characterized by mild and late-onset PKD, with large renal cysts and limited kidney insufficiency. Extrarenal manifestations, including liver cysts, were rarely seen. Conclusion: Our data suggest the monoallelic pathogenic IFT140 variants are the third most common cause of the ADPKD-spectrum phenotype in Italy, usually associated with a mild and atypical renal cystic disease.

Prenatal vs postnatal diagnosis of 22q11.2 deletion syndrome: cardiac and noncardiac outcomes through 1 year of age.

BACKGROUND: The 22q11.2 deletion syndrome is the most common microdeletion syndrome and is frequently associated with congenital heart disease. Prenatal diagnosis of 22q11.2 deletion syndrome is increasingly offered. It is unknown whether there is a clinical benefit to prenatal detection as compared with postnatal diagnosis. OBJECTIVE: This study aimed to determine differences in perinatal and infant outcomes between patients with prenatal and postnatal diagnosis of 22q11.2 deletion syndrome. STUDY DESIGN: This was a retrospective cohort study across multiple international centers (30 sites, 4 continents) from 2006 to 2019. Participants were fetuses, neonates, or infants with a genetic diagnosis of 22q11.2 deletion syndrome by 1 year of age with or without congenital heart disease; those with prenatal diagnosis or suspicion (suggestive ultrasound findings and/or high-risk cell-free fetal DNA screen for 22q11.2 deletion syndrome with postnatal confirmation) were compared with those with postnatal diagnosis. Perinatal management, cardiac and noncardiac morbidity, and mortality by 1 year were assessed. Outcomes were adjusted for presence of critical congenital heart disease, gestational age at birth, and site. RESULTS: A total of 625 fetuses, neonates, or infants with 22q11.2 deletion syndrome (53.4% male) were included: 259 fetuses were prenatally diagnosed (156 [60.2%] were live-born) and 122 neonates were prenatally suspected with postnatal confirmation, whereas 244 infants were postnatally diagnosed. In the live-born cohort (n=522), 1-year mortality was 5.9%, which did not differ between groups but differed by the presence of critical congenital heart disease (hazard ratio, 4.18; 95% confidence interval, 1.56-11.18; P<.001) and gestational age at birth (hazard ratio, 0.78 per week; 95% confidence interval, 0.69-0.89; P<.001). Adjusting for critical congenital heart disease and gestational age at birth, the prenatal cohort was less likely to deliver at a local community hospital (5.1% vs 38.2%; odds ratio, 0.11; 95% confidence interval, 0.06-0.23; P<.001), experience neonatal cardiac decompensation (1.3% vs 5.0%; odds ratio, 0.11; 95% confidence interval, 0.03-0.49; P=.004), or have failure to thrive by 1 year (43.4% vs 50.3%; odds ratio, 0.58; 95% confidence interval, 0.36-0.91; P=.019). CONCLUSION: Prenatal detection of 22q11.2 deletion syndrome was associated with improved delivery management and less cardiac and noncardiac morbidity, but not mortality, compared with postnatal detection.

Leader peptide or pro-segment mutants of renin are misrouted to mitochondria in autosomal dominant tubulointerstitial kidney disease.

Autosomal dominant tubulointerstitial kidney disease (ADTKD), a rare genetic disorder characterised by progressive chronic kidney disease, is caused by mutations in different genes, including REN, encoding renin. Renin is a secreted protease composed of three domains: the leader peptide that allows insertion in the endoplasmic reticulum (ER), a pro-segment regulating its activity, and the mature part of the protein. Mutations in mature renin lead to ER retention of the mutant protein and to late-onset disease, whereas mutations in the leader peptide, associated with defective ER translocation, and mutations in the pro-segment, leading to accumulation in the ER-to-Golgi compartment, lead to a more severe, early-onset disease. In this study, we demonstrate a common, unprecedented effect of mutations in the leader peptide and pro-segment as they lead to full or partial mistargeting of the mutated proteins to mitochondria. The mutated pre-pro-sequence of renin is necessary and sufficient to drive mitochondrial rerouting, mitochondrial import defect and fragmentation. Mitochondrial localisation and fragmentation were also observed for wild-type renin when ER translocation was affected. These results expand the spectrum of cellular phenotypes associated with ADTKD-associated REN mutations, providing new insight into the molecular pathogenesis of the disease.

Identification of bi-allelic LFNG variants in three patients and further clinical and molecular refinement of spondylocostal dysostosis 3.

Spondylocostal dysostosis (SCD), a condition characterized by multiple segmentation defects of the vertebrae and rib malformations, is caused by bi-allelic variants in one of the genes involved in the Notch signaling pathway that tunes the "segmentation clock" of somitogenesis: DLL3, HES7, LFNG, MESP2, RIPPLY2, and TBX6. To date, seven individuals with LFNG variants have been reported in the literature. In this study we describe two newborns and one fetus with SCD, who were found by trio-based exome sequencing (trio-ES) to carry homozygous (c.822-5C>T) or compound heterozygous (c.[863dup];[1063G>A]) and (c.[521G>T];[890T>G]) variants in LFNG. Notably, the c.822-5C>T change, affecting the polypyrimidine tract of intron 5, is the first non-coding variant reported in LFNG. This study further refines the clinical and molecular features of spondylocostal dysostosis 3 and adds to the numerous investigations supporting the usefulness of trio-ES approach in prenatal and neonatal settings.

Rare Single Nucleotide and Copy Number Variants and the Etiology of Congenital Obstructive Uropathy: Implications for Genetic Diagnosis.

SIGNIFICANCE STATEMENT: Congenital obstructive uropathy (COU) is a prevalent human developmental defect with highly heterogeneous clinical presentations and outcomes. Genetics may refine diagnosis, prognosis, and treatment, but the genomic architecture of COU is largely unknown. Comprehensive genomic screening study of 733 cases with three distinct COU subphenotypes revealed disease etiology in 10.0% of them. We detected no significant differences in the overall diagnostic yield among COU subphenotypes, with characteristic variable expressivity of several mutant genes. Our findings therefore may legitimize a genetic first diagnostic approach for COU, especially when burdening clinical and imaging characterization is not complete or available. BACKGROUND: Congenital obstructive uropathy (COU) is a common cause of developmental defects of the urinary tract, with heterogeneous clinical presentation and outcome. Genetic analysis has the potential to elucidate the underlying diagnosis and help risk stratification. METHODS: We performed a comprehensive genomic screen of 733 independent COU cases, which consisted of individuals with ureteropelvic junction obstruction ( n =321), ureterovesical junction obstruction/congenital megaureter ( n =178), and COU not otherwise specified (COU-NOS; n =234). RESULTS: We identified pathogenic single nucleotide variants (SNVs) in 53 (7.2%) cases and genomic disorders (GDs) in 23 (3.1%) cases. We detected no significant differences in the overall diagnostic yield between COU sub-phenotypes, and pathogenic SNVs in several genes were associated to any of the three categories. Hence, although COU may appear phenotypically heterogeneous, COU phenotypes are likely to share common molecular bases. On the other hand, mutations in TNXB were more often identified in COU-NOS cases, demonstrating the diagnostic challenge in discriminating COU from hydronephrosis secondary to vesicoureteral reflux, particularly when diagnostic imaging is incomplete. Pathogenic SNVs in only six genes were found in more than one individual, supporting high genetic heterogeneity. Finally, convergence between data on SNVs and GDs suggest MYH11 as a dosage-sensitive gene possibly correlating with severity of COU. CONCLUSIONS: We established a genomic diagnosis in 10.0% of COU individuals. The findings underscore the urgent need to identify novel genetic susceptibility factors to COU to better define the natural history of the remaining 90% of cases without a molecular diagnosis.

Autosomal Dominant Tubulointerstitial Kidney Disease: An Emerging Cause of Genetic CKD.

Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a rare inherited disorder characterized by progressive loss of kidney function, nonsignificant urinalysis and tubulointerstitial fibrosis. ADTKD progresses to end stage renal disease (ESRD) in adulthood. The classification of ADTKD is an evolving concept and the agreement is now that, due to the overlap in terms of phenotype characteristics, this should be based on the involved gene. The umbrella term ADTKD therefore includes different conditions as follows: ADTKD-UMOD, ADKTD-MUC1, ADTKD-REN, and ADTK-HNF1B, with ADTKD-SEC61A1 and ADTKD-DNAJB11 as a further rare and atypical diagnosis recently described. The employment of next-generation sequencing (NGS) as a diagnostic tool in patients with familial kidney disease has improved the diagnostic accuracy in this field with ADTKD now being considered the third genetic cause of renal disease worldwide after autosomal dominant polycystic kidney disease (ADPKD) and Alport syndrome. On average, the disease pathogenesis is similar across the different subtypes, With the exception of HNF1B, the different mutated genes give rise to misfolded proteins leading to cellular stress and cytotoxicity. Research is now focused in better defining the underlying mechanism of fibrosis to guide therapeutic interventions. The aim of this review is to discuss how the knowledge of ADTKD has evolved in the last decades, with emphasis on the clinical features, molecular diagnosis, and pathogenic aspects of the different diseases included under the ADTKD term.

Expanding the variability of the ADPKD-GANAB clinical phenotype in a family of Italian ancestry.

BACKGROUND: Causative mutations in the GANAB gene have been described in only 14 families, 9 diagnosed with late-onset Autosomal Dominant Polycystic Kidney Disease (ADPKD) and 5 with Autosomal Dominant Polycystic Liver Disease (ADPLD). CASE: Diagnosis of ADPKD was made in a 45-year old man during screening for hernia repair. CT scan showed enlarged cystic kidneys, nephrolithiasis and normal-sized liver with multiple cysts. Hematuria, hypertension and aortic root dilatation were also documented. Renal function was normal. Molecular analysis of PKD genes disclosed a heterozygous p.R839W GANAB variant inherited from the mother. Both his elderly parents presented normal-sized bilateral cystic kidneys but normal renal function. The GANAB-ADPKD mother had no liver cysts. The father was screened for PKD-related genes and no variant was found. GENETIC ANALYSIS: We describe a new family with late-onset ADPKD due to the p.R839W GANAB variant, previously reported in a severe ADPLD patient, requiring liver transplantation. DISCUSSION: Since ADPKD-GANAB is an ultrarare, recently described disease, reporting further patients may help unraveling gene-related phenotype. In our patients the p.R839W GANAB variant was not related to severe ADPLD, as previously reported, but with mild ADPKD and a plethora of renal and extrarenal manifestations, usually described in PKD1/PKD2 patients. The evidence that the GANAB variant may cause both ADPKD and ADPLD of variable severity supports that renal and hepatic cystogenesis are the result of a common defective polycystin-1 pathway.

[ADPKD and intracranial aneurysms: indications for screening, follow-up and clinical management].

Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent hereditary nephropathy and is the fourth most common cause for end-stage renal disease in Europe. ADPKD is a systemic disease; besides the typical renal involvement, characterized by progressive cyst expansion leading to massive enlargement and distortion of the kidney architecture and, ultimately, to end-stage renal disease, multiple extrarenal manifestations can be observed included cysts in other organs, diverticulosis, cardiac valvulopathies, abdominal and inguinal hernias, vascular anomalies. The rupture of an intracranial aneurysm is one of the most serious complications in ADPKD patients. Aim of this review is to provide useful indications for the clinician to define the risk of intracranial aneurysms in ADPKD population, to identify screening criteria (which patients to screen, how often and with which diagnostic methods), to estimate the risk of rupture of intracranial aneurysms, which may require intervention.

Copy Number Variant Analysis and Genome-wide Association Study Identify Loci with Large Effect for Vesicoureteral Reflux.

BACKGROUND: Vesicoureteral reflux (VUR) is a common, familial genitourinary disorder, and a major cause of pediatric urinary tract infection (UTI) and kidney failure. The genetic basis of VUR is not well understood. METHODS: A diagnostic analysis sought rare, pathogenic copy number variant (CNV) disorders among 1737 patients with VUR. A GWAS was performed in 1395 patients and 5366 controls, of European ancestry. RESULTS: Altogether, 3% of VUR patients harbored an undiagnosed rare CNV disorder, such as the 1q21.1, 16p11.2, 22q11.21, and triple X syndromes ((OR, 3.12; 95% CI, 2.10 to 4.54; P=6.35×10-8) The GWAS identified three study-wide significant and five suggestive loci with large effects (ORs, 1.41-6.9), containing canonical developmental genes expressed in the developing urinary tract (WDPCP, OTX1, BMP5, VANGL1, and WNT5A). In particular, 3.3% of VUR patients were homozygous for an intronic variant in WDPCP (rs13013890; OR, 3.65; 95% CI, 2.39 to 5.56; P=1.86×10-9). This locus was associated with multiple genitourinary phenotypes in the UK Biobank and eMERGE studies. Analysis of Wnt5a mutant mice confirmed the role of Wnt5a signaling in bladder and ureteric morphogenesis. CONCLUSIONS: These data demonstrate the genetic heterogeneity of VUR. Altogether, 6% of patients with VUR harbored a rare CNV or a common variant genotype conferring an OR >3. Identification of these genetic risk factors has multiple implications for clinical care and for analysis of outcomes in VUR.

Variable Expressivity of HNF1B Nephropathy, From Renal Cysts and Diabetes to Medullary Sponge Kidney Through Tubulo-interstitial Kidney Disease.

INTRODUCTION: In humans, heterozygous mutations of hepatocyte nuclear factor 1beta (HNF1B) are responsible for a dominant inherited disease with both renal and extrarenal phenotypes. HNF1B nephropathy is the umbrella term that includes the various kidney phenotypes of the disease, ranging from congenital anomalies of the kidney and urinary tract (CAKUT), to tubular transport abnormalities, to chronic tubulointerstitial and cystic renal disease. METHODS: We describe 7 families containing 13 patients with ascertained HNF1B nephropathy. All patients underwent genetic testing and clinical, laboratory, and instrumental assessment, including renal imaging and evaluation of extrarenal HNF1B manifestations. RESULTS: Significant inter- and intrafamilial variability of HNF1B nephropathy has been observed. In our cohort, HNF1B pathogenic variants presented with renal cysts and diabetes syndrome (RCAD); renal cystic phenotype mimicking autosomal dominant polycystic kidney disease (ADPKD); autosomal dominant tubulointerstitial kidney disease (ADTKD) with or without hyperuricemia and gout; CAKUT; and nephrogenic diabetes insipidus (NDI). Of note, for the first time, we describe the occurrence of medullary sponge kidney (MSK) in a family harboring the HNF1B whole-gene deletion at chromosome 17q12. Genotype characterization led to the identification of an additional 6 novel HNF1B pathogenic variants, 3 frameshift, 2 missense, and 1 nonsense. CONCLUSION: HNF1B nephropathy may present with a highly variable renal phenotype in adult patients. We expand the HNF1B renal clinical picture to include MSK as a potential new finding. Finally, we expand the allelic repertoire of the disease by adding novel HNF1B pathogenic variants.

Genetic and Clinical Predictors of Age of ESKD in Individuals With Autosomal Dominant Tubulointerstitial Kidney Disease Due to UMOD Mutations.

INTRODUCTION: Autosomal dominant tubulo-interstitial kidney disease due to UMOD mutations (ADTKD-UMOD) is a rare condition associated with high variability in the age of end-stage kidney disease (ESKD). The minor allele of rs4293393, located in the promoter of the UMOD gene, is present in 19% of the population and downregulates uromodulin production by approximately 50% and might affect the age of ESKD. The goal of this study was to better understand the genetic and clinical characteristics of ADTKD-UMOD and to perform a Mendelian randomization study to determine if the minor allele of rs4293393 was associated with better kidney survival. METHODS: An international group of collaborators collected clinical and genetic data on 722 affected individuals from 249 families with 125 mutations, including 28 new mutations. The median age of ESKD was 47 years. Men were at a much higher risk of progression to ESKD (hazard ratio 1.78, P < 0.001). RESULTS: The allele frequency of the minor rs4293393 allele was only 11.6% versus the 19% expected (P < 0.01), resulting in Hardy-Weinberg disequilibrium and precluding a Mendelian randomization experiment. An in vitro score reflecting the severity of the trafficking defect of uromodulin mutants was found to be a promising predictor of the age of ESKD. CONCLUSION: We report the clinical characteristics associated with 125 UMOD mutations. Male gender and a new in vitro score predict age of ESKD.

Testicular Involvement is a Hallmark of Apo A-I Leu75Pro Mutation Amyloidosis.

CONTEXT: Apo A-I Leu75Pro is a rare hereditary form of amyloidosis that mainly involves the kidney, the liver, and the testis. OBJECTIVE: To define the characteristics of organ damage and testis impairment in the largest cohort collected to date of men with Apo A-I Leu75Pro amyloidosis. DESIGN, SETTING, AND PATIENTS: Retrospective study from a prospectively collected database of 129 male subjects >18 years with Apo A-I Leu75Pro amyloidosis from a reference center at the University Hospital of Brescia, Italy. MAIN OUTCOME MEASURES: We evaluated liver and renal function, scrotal ultrasound, reproductive hormone levels, testis biopsy, hypogonadal symptoms, and fertility. RESULTS: Progressive involvement of testis, kidney, and liver was observed in 96/129 (74.4%) cases. Testis impairment was found in 88/129 patients (68.2%), liver in 59 (45.7%) and renal in 50 (38.8%). Testis damage was often the first manifestation of the disease and the only dysfunction in 30% of younger patients (<38 years). Testicular involvement was characterized mainly by primary (73/88 patients, 83.0%) and subclinical (8/88, 9.1%) hypogonadism. Almost all (85/88, 96.6%) also had high follicle-stimulating hormone, suggesting a primary global damage of endocrine and spermatogenic functions, and 30% of them did not conceive. Macroorchidism was found in 53/88 (60.2%) patients, especially in men <54 years (30/33, 90.9%). Apo A-I amyloid deposits were found in Sertoli cells, germinal epithelium, and vessel walls. CONCLUSION: In men with Apo A-I Leu75Pro amyloidosis, testicular involvement is the hallmark of the disease, characterized by global primary testicular dysfunction and macroorchidism due to amyloid deposits.

An international cohort study of autosomal dominant tubulointerstitial kidney disease due to REN mutations identifies distinct clinical subtypes.

There have been few clinical or scientific reports of autosomal dominant tubulointerstitial kidney disease due to REN mutations (ADTKD-REN), limiting characterization. To further study this, we formed an international cohort characterizing 111 individuals from 30 families with both clinical and laboratory findings. Sixty-nine individuals had a REN mutation in the signal peptide region (signal group), 27 in the prosegment (prosegment group), and 15 in the mature renin peptide (mature group). Signal group patients were most severely affected, presenting at a mean age of 19.7 years, with the prosegment group presenting at 22.4 years, and the mature group at 37 years. Anemia was present in childhood in 91% in the signal group, 69% prosegment, and none of the mature group. REN signal peptide mutations reduced hydrophobicity of the signal peptide, which is necessary for recognition and translocation across the endoplasmic reticulum, leading to aberrant delivery of preprorenin into the cytoplasm. REN mutations in the prosegment led to deposition of prorenin and renin in the endoplasmic reticulum-Golgi intermediate compartment and decreased prorenin secretion. Mutations in mature renin led to deposition of the mutant prorenin in the endoplasmic reticulum, similar to patients with ADTKD-UMOD, with a rate of progression to end stage kidney disease (63.6 years) that was significantly slower vs. the signal (53.1 years) and prosegment groups (50.8 years) (significant hazard ratio 0.367). Thus, clinical and laboratory studies revealed subtypes of ADTKD-REN that are pathophysiologically, diagnostically, and clinically distinct.

[The complex etiopathogenesis of focal segmental glomerulosclerosis].

Focal segmental glomerulosclerosis (FSGS) is a pathological spectrum subtended by heterogeneous etiologies. A good knowledge of FSGS and its causes should be included in the nephrologists' clinical background, as it deeply influences the subsequent management of the affected patients. In fact, while immunosuppressive treatment should be considered in idiopathic FSGS, the treatment of secondary forms should primarily aim at curing or containing the underpinning etiologic factors. Furthermore, in contrast to secondary FSGS, idiopathic FSGS tends to relapse after kidney transplantation. Although FSGS has a wide spectrum of etiologies, several pathogenetic "moments" are shared. Furthermore, recent studies have identified a pool of glomerular cells potentially capable of regenerating lost podocytes; these cells might represent a promising therapeutic target. The primary aim of this review is to describe the etiologic factors associated with FSGS, with a focus on the main pathogenetic mechanisms involved in its development.

Outcomes in pregnancies with a confined placental mosaicism and implications for prenatal screening using cell-free DNA.

PURPOSE: To assess the association between confined placental mosaicism (CPM) and adverse pregnancy outcome. METHODS: A retrospective cohort study was carried out evaluating the outcome of pregnancies with and without CPM involving a rare autosomal trisomy (RAT) or tetraploidy. Birthweight, gestational age at delivery, fetal growth restriction (FGR), Apgar score, neonatal intensive care admission, preterm delivery, and hypertensive disorders of pregnancy were considered. RESULTS: Overall 181 pregnancies with CPM and 757 controls were recruited. Outcome information was available for 69% of cases (n = 124) and 62% of controls (n = 468). CPM involving trisomy 16 (T16) was associated with increased incidence of birthweight <3rd centile (P = 0.007, odds ratio [OR] = 11.2, 95% confidence interval [CI] = 2.7-47.1) and preterm delivery (P = 0.029, OR = 10.2, 95% CI = 1.9-54.7). For the other RATs, an association with prenatally diagnosed FGR was not supported by birthweight data and there were no other strong associations with adverse outcomes. CONCLUSION: Excluding T16, the incidence of adverse pregnancy outcomes for pregnancies carrying a CPM is low. RATs can also be identified through genome-wide cell-free DNA screening. Because most of these will be attributable to CPMs, we conclude that this screening is of minimal benefit.

Autosomal Dominant Tubulointerstitial Kidney Disease with Adult Onset due to a Novel Renin Mutation Mapping in the Mature Protein.

Autosomal dominant tubulointerstitial kidney disease (ADTKD) is a genetically heterogeneous renal disorder leading to progressive loss of renal function. ADTKD-REN is due to rare mutations in renin, all localized in the protein leader peptide and affecting its co-translational insertion in the endoplasmic reticulum (ER). Through exome sequencing in an adult-onset ADTKD family we identified a new renin variant, p.L381P, mapping in the mature protein. To assess its pathogenicity, we combined genetic data, computational and predictive analysis and functional studies. The L381P substitution affects an evolutionary conserved residue, co-segregates with renal disease, is not found in population databases and is predicted to be deleterious by in silico tools and by structural modelling. Expression of the L381P variant leads to its ER retention and induction of the Unfolded Protein Response in cell models and to defective pronephros development in zebrafish. Our work shows that REN mutations outside of renin leader peptide can cause ADTKD and delineates an adult form of ADTKD-REN, a condition which has usually its onset in childhood. This has implications for the molecular diagnosis and the estimated prevalence of the disease and points at ER homeostasis as a common pathway affected in ADTKD-REN, and possibly more generally in ADTKD.