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.

Targeted next-generation sequencing study in familial ALS-FTD Portuguese patients negative for C9orf72 HRE.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with clinical and etiological heterogeneity and a complex genetic contribution. Clinical, neuropathological, and genetic evidence revealed that ALS and frontotemporal dementia (FTD) are in part of a single disease continuum. Genetic causes have been identified in sporadic (SALS) and familial patients (FALS) and the recurrent genetic factor underlying ALS and FTD is the C9orf72 hexanucleotide repeat expansion (HRE). However, in our population, the concomitance of ALS and FTD cannot be explained by C9orf72 HRE in many FALS and SALS cases. Our aim is to further understand the genetic basis of ALS in Portuguese patients. 34 patients with FALS or SALS-FTD, negative for C9orf72 HRE, were screened for rare variants in a panel of 29 relevant genes by next-generation sequencing. We detected 15 variants in 11 genes, one classified as pathogenic in TARDBP, two as likely pathogenic in TARDBP and PRPH, and the others as variants of unknown significance (VUS). Gene variants, including VUS, were found in 41.2% FALS patients and 40% SALS-FTD. In most patients, no potential pathogenic variants were found. Our results emphasize the need to enhance the efforts to unravel the genetic architecture of ALS-FTD.

Effect of Tumor Necrosis Factor Inhibitor Therapy on Osteoclasts Precursors in Ankylosing Spondylitis.

INTRODUCTION: Ankylosing Spondylitis (AS) is characterized by excessive local bone formation and concomitant systemic bone loss. Tumor necrosis factor (TNF) plays a central role in the inflammation of axial skeleton and enthesis of AS patients. Despite reduction of inflammation and systemic bone loss, AS patients treated with TNF inhibitors (TNFi) have ongoing local bone formation. The aim of this study was to assess the effect of TNFi in the differentiation and activity of osteoclasts (OC) in AS patients. METHODS: 13 AS patients treated with TNFi were analyzed at baseline and after a minimum follow-up period of 6 months. 25 healthy donors were recruited as controls. Blood samples were collected to assess receptor activator of nuclear factor kappa-B ligand (RANKL) surface expression on circulating leukocytes and frequency and phenotype of monocyte subpopulations. Quantification of serum levels of bone turnover markers and cytokines, in vitro OC differentiation assay and qRT-PCR for OC specific genes were performed. RESULTS: RANKL+ circulating lymphocytes (B and T cells) and IL-17A, IL-23 and TGF-ß levels were decreased after TNFi treatment. We found no differences in the frequency of the different monocyte subpopulations, however, we found decreased expression of CCR2 and increased expression of CD62L after TNFi treatment. OC number was reduced in patients at baseline when compared to controls. OC specific gene expression was reduced in circulating OC precursors after TNFi treatment. However, when cultured in OC differentiating conditions, OC precursors from AS TNFi-treated patients showed increased activity as compared to baseline. CONCLUSION: In AS patients, TNFi treatment reduces systemic pro osteoclastogenic stimuli. However, OC precursors from AS patients exposed to TNFi therapy have increased in vitro activity in response to osteoclastogenic stimuli.