SLC26A1 is a major determinant of sulfate homeostasis in humans

Sulfate plays a pivotal role in numerous physiological processes in the human body, including bone and cartilage health. A role of the anion transporter SLC26A1 (Sat1) for sulfate reabsorption in the kidney is supported by the observation of hyposulfatemia and hypersulfaturia in Slc26a1-knockout mice. The impact of SLC26A1 on sulfate homeostasis in humans remains to be defined. By combining clinical genetics, functional expression assays, and population exome analysis, we identify SLC26A1 as a sulfate transporter in humans and experimentally validate several loss-of-function alleles. Whole-exome sequencing from a patient presenting with painful perichondritis, hyposulfatemia, and renal sulfate wasting revealed a homozygous mutation in SLC26A1, which has not been previously described to the best of our knowledge. Whole-exome data analysis of more than 5,000 individuals confirmed that rare, putatively damaging SCL26A1 variants were significantly associated with lower plasma sulfate at the population level. Functional expression assays confirmed a substantial reduction in sulfate transport for the SLC26A1 mutation of our patient, which we consider to be novel, as well as for the additional variants detected in the population study. In conclusion, combined evidence from 3 complementary approaches supports SLC26A1 activity as a major determinant of sulfate homeostasis in humans. In view of recent evidence linking sulfate homeostasis with back pain and intervertebral disc disorder, our study identifies SLC26A1 as a potential target for modulation of musculoskeletal health

Maternal variants in NLRP and other maternal effect proteins are associated with multilocus imprinting disturbance in offspring

Background: Genomic imprinting results from the resistance of germline epigenetic marks to reprogramming in the early embryo for a small number of mammalian genes. Genetic, epigenetic or environmental insults that prevent imprints from evading reprogramming may result in imprinting disorders, which impact growth, development, behaviour and metabolism. We aimed to identify genetic defects causing imprinting disorders, by whole-exome sequencing in families with one or more members affected by multi-locus imprinting disturbance. Methods: Whole-exome sequencing was performed in 38 pedigrees where probands had multi-locus imprinting disturbance, in five of whom, maternal variants in NLRP5 have previously been found. Results: We now report 15 further pedigrees in which offspring had disturbance of imprinting, while their mothers had rare, predicted-deleterious variants in maternal-effect genes, including NLRP2, NLRP7 and PADI6. As well as clinical features of well-recognised imprinting disorders, some offspring had additional features including developmental delay, behavioural problems and discordant monozygotic twinning, while some mothers had reproductive problems including pregnancy loss. Conclusion: The identification of 20 putative maternal-effect variants in 38 families affected by multi-locus imprinting disorders adds to the evidence that maternal genetic factors affect oocyte fitness and thus offspring development. Testing for maternal-effect genetic variants should be considered in families affected by atypical imprinting disorders.<br/

Narrating autocracy - political discourse in Latin America's pink tide

Diese Arbeit untersucht die Autokratisierung der "Pink Tide" in Lateinamerika zwischen 1999 und 2017 mit den Präsidentschaften von Hugo Chávez (Venezuela), Rafael Correa (Ecuador) und Evo Morales (Bolivien). Die Studie untersucht die Rolle des Diskurses - insbesondere der Legitimationsnarrative - in autoritären Konsolidierungen. Die Arbeit fragt wie Legitimation während ihrer autoritären Konsolidierung diskursiv konstruiert und aufrechterhalten wird. Die Studie bietet die Theorie der Legitimology - eine Mischung aus Management-Legitimationstheorie und Narratologie - zur Analyse von Pink-Tide-Legitimationsnarrativen und entwickelt die Methodik einer strukturierten, fokussierten narrativen Analyse, um die empirische Forschung zu leiten. Die empirische Studie umreißt die Erzählungen, Positionierungen und Handlungsstränge in den oben genannten Präsidentschaften. Schließlich fasst die Studie die wichtigsten Ergebnisse zusammen und kommt zu dem Schluss, dass die Autokratisierung als empirisches Ergebnis einer Reihe komplexer, wechselseitiger Legitimationswechselwirkungen auftritt. Die Arbeit schlägt ein neuartiges theoretisches Modell vor, um Legitimationszyklen zu konzipieren und weist auf zukünftige Forschungsperspektiven hin.This thesis investigates the autocratization of the Pink Tide in Latin America between 1999-2017, focusing on the presidencies of Hugo Chávez (Venezuela), Rafael Correa (Ecuador) and Evo Morales (Bolivia). The study explores the role of discourse—specifically, that of legitimation narratives— in authoritarian consolidations. It hypothesizes that legitimation narratives underpin the evolution of the Pink Tide governments and seeks to understand how legitimation is discursively constructed and upheld throughout autocratization. The thesis first appraises relevant literature on legitimation, autocratization and the Pink Tide. Subsequently, it offers the theory of legitimology—a hybrid of management legitimation theory and narratology— to analyze Pink Tide legitimation narratives. Third, it develops the methodology of a structured, focused narrative analysis to guide the empirical research. Fourth, it conducts an empirical study on legitimation narratives in the aforementioned presidencies, outlining their respective narratives, positioning and storylines. Finally, the study summarizes main findings and concludes that autocratization emerges as the empirical result of a series of complex, reciprocal legitimation interactions. The thesis proposes a novel theoretical model to conceptualize legitimation cycles and points to future research prospects

Comprehensive analysis of the <i>MLH1</i> promoter region in 480 patients with colorectal cancer and 1150 controls reveals new variants including one with a heritable constitutional <i>MLH1</i> epimutation

BackgroundGermline defects in MLH1, MSH2, MSH6 and PMS2 predisposing for Lynch syndrome (LS) are mainly based on sequence changes, whereas a constitutional epimutation of MLH1(CEM) is exceptionally rare. This abnormal MLH1 promoter methylation is not hereditary when arising de novo, whereas a stably heritable and variant-induced CEM was described for one single allele. We searched for MLH1 promoter variants causing a germline or somatic methylation induction or transcriptional repression.MethodsWe analysed the MLH1 promoter sequence in five different patient groups with colorectal cancer (CRC) (n=480) composed of patients with i) CEM (n=16), ii) unsolved loss of MLH1 expression in CRC (n=37), iii) CpG-island methylator-phenotype CRC (n=102), iv) patients with LS (n=83) and v) MLH1-proficient CRC (n=242) as controls. 1150 patients with non-LS tumours also served as controls to correctly judge the results.ResultsWe detected 10 rare MLH1 promoter variants. One novel, complex MLH1 variant c.-63_-58delins18 is present in a patient with CRC with CEM and his sister, both showing a complete allele-specific promoter methylation and transcriptional silencing. The other nine promoter variants detected in 17 individuals were not associated with methylation. For four of these, a normal, biallelic MLH1 expression was found in the patients' cDNA.ConclusionWe report the second promoter variant stably inducing a hereditary CEM. Concerning the classification of promoter variants, we discuss contradictory results from the literature for two variants, describe classification discrepancies between existing rules for five variants, suggest the (re-)classification of five promoter variants to (likely) benign and regard four variants as functionally unclear.</jats:sec

Maternal variants in NLRP and other maternal effect proteins are associated with multilocus imprinting disturbance in offspring

Background Genomic imprinting results from the resistance of germline epigenetic marks to reprogramming in the early embryo for a small number of mammalian genes. Genetic, epigenetic or environmental insults that prevent imprints from evading reprogramming may result in imprinting disorders, which impact growth, development, behaviour and metabolism. We aimed to identify genetic defects causing imprinting disorders by whole-exome sequencing in families with one or more members affected by multilocus imprinting disturbance. Methods Whole-exome sequencing was performed in 38 pedigrees where probands had multilocus imprinting disturbance, in five of whom maternal variants in NLRP5 have previously been found. Results We now report 15 further pedigrees in which offspring had disturbance of imprinting, while their mothers had rare, predicted-deleterious variants in maternal effect genes, including NLRP2, NLRP7 and PADI6. As well as clinical features of well-recognised imprinting disorders, some offspring had additional features including developmental delay, behavioural problems and discordant monozygotic twinning, while some mothers had reproductive problems including pregnancy loss. Conclusion The identification of 20 putative maternal effect variants in 38 families affected by multilocus imprinting disorders adds to the evidence that maternal genetic factors affect oocyte fitness and thus offspring development. Testing for maternal-effect genetic variants should be considered in families affected by atypical imprinting disorders

TSPY expression is variably altered in transgenic mice with testicular feminization

TSPY (testis-specific protein, Y-encoded) genes are expressed in premeiotic germ cells and round spermatids. The topology and timing of TSPY expression, and also its homology to members of the TTSN-family, suggest that TSPY is a proliferation factor for germ cells. There is also evidence for a role of TSPY in the aetiology of testis cancer. TSPY is a candidate for GBY, the elusive gonadoblastoma locus on the human Y chromosome, which is thought to predispose dysgenetic gonads of 46, XY sex-reversed females to develop gonadoblastoma. We have previously generated a TSPY transgenic mouse line (Tg(TSPY)9Jshm) that carries approximately 50 copies of the human TSPY gene on the mouse Y chromosome. in order to elucidate TSPY expression under complete androgen insensitivity and to investigate a possible role of TSPY in gonadal tumorigenesis, we have now generated sex-reversed TSPY transgenic Ar(Tfm) mice hemizygous for the X-linked testicular feminization mutation (Ar(Tfm)). We can show that the TSPY transcript is aberrantly spliced in the testes of TSPY-Ar(Tfm) mice, and that TSPY expression is upregulated by androgen insensitivity in some but not all animals. TSPY transgenic mice showed significantly increased testes weights. In one TSPY transgenic Ar(Tfm) animal, spermatogenesis proceeded beyond meiotic prophase. No tumors of germ cell origin were found in the testes of TSPY-Ar(Tfm) mice. Five out of 46 TSPY transgenic Ar(Tfm) mice, and 3 out of 31 age-related NMRI-Ar(Tfm) controls developed Leydig cell tumors, whereas none of the age-matched Ar(Tfm) mice (n = 44) on a wild type background were affected by Leydig cell tumorigenesis