Noncoding deletions reveal a gene that is critical for intestinal function.

Large-scale genome sequencing is poised to provide a substantial increase in the rate of discovery of disease-associated mutations, but the functional interpretation of such mutations remains challenging. Here we show that deletions of a sequence on human chromosome 16 that we term the intestine-critical region (ICR) cause intractable congenital diarrhoea in infants1,2. Reporter assays in transgenic mice show that the ICR contains a regulatory sequence that activates transcription during the development of the gastrointestinal system. Targeted deletion of the ICR in mice caused symptoms that recapitulated the human condition. Transcriptome analysis revealed that an unannotated open reading frame (Percc1) flanks the regulatory sequence, and the expression of this gene was lost in the developing gut of mice that lacked the ICR. Percc1-knockout mice displayed phenotypes similar to those observed upon ICR deletion in mice and patients, whereas an ICR-driven Percc1 transgene was sufficient to rescue the phenotypes found in mice that lacked the ICR. Together, our results identify a gene that is critical for intestinal function and underscore the need for targeted in vivo studies to interpret the growing number of clinical genetic findings that do not affect known protein-coding genes

Defective binding of ETS1 and STAT4 due to a mutation in the promoter region of THPO as a novel mechanism of congenital amegakaryocytic thrombocytopenia

Congenital amegakaryocytic thrombocytopenia (CAMT) is a recessive disorder characterized by severe reduction of megakaryocytes and platelets at birth, which evolves toward bone marrow aplasia in childhood. CAMT is mostly caused by mutations in MPL (CAMT-MPL), the gene encoding the receptor of thrombopoietin (THPO), a crucial cytokine regulating hematopoiesis. CAMT can be also due to mutations affecting the THPO coding region (CAMT-THPO). In a child with CAMT clinical picture, we identified the homozygous c.-323C>T substitution, affecting a potential regulatory region of THPO. Though mechanisms controlling the THPO transcription are not characterized, bioinformatics and in vitro analysis showed that c.-323C>T prevents the binding of transcription factors ETS1 and STAT4 to the putative THPO promoter, impairing THPO expression. Accordingly, in the proband the serum THPO concentration indicates defective THPO production. Based on these findings, the patient was treated with the THPOmimetic agent eltrombopag, inducing a significant increase in platelet count and stable remission of bleeding symptoms. Herein, we report a novel pathogenic variant responsible for CAMT and provide new insights into the mechanisms regulating the transcription of the THPO gene

The Formation of Highly Soluble Oligomers of α-Synuclein Is Regulated by Fatty Acids and Enhanced in Parkinson's Disease

AbstractAccumulation of misfolded proteins as insoluble aggregates occurs in several neurodegenerative diseases. In Parkinson's disease (PD) and dementia with Lewy bodies (DLB), α-synuclein (αS) accumulates in insoluble inclusions. To identify soluble αS oligomers that precede insoluble aggregates, we probed the cytosols of mesencephalic neuronal (MES) cells, normal and αS-transgenic mouse brains, and normal, PD, and DLB human brains. All contained highly soluble oligomers of αS whose detection was enhanced by delipidation. Exposure of living MES neurons to polyunsaturated fatty acids (PUFAs) increased αS oligomer levels, whereas saturated FAs decreased them. PUFAs directly promoted oligomerization of recombinant αS. Transgenic mice accumulated soluble oligomers with age. PD and DLB brains had elevated amounts of the soluble, lipid-dependent oligomers. We conclude that αS interacts with PUFAs in vivo to promote the formation of highly soluble oligomers that precede the insoluble αS aggregates associated with neurodegeneration

Deficiency of Asparagine Synthetase Causes Congenital Microcephaly and a Progressive Form of Encephalopathy

International audienceWe analyzed four families that presented with a similar condition characterized by congenital micro-cephaly, intellectual disability, progressive cerebral atrophy, and intractable seizures. We show that recessive mutations in the ASNS gene are responsible for this syndrome. Two of the identified missense mutations dramatically reduce ASNS protein abundance, suggesting that the mutations cause loss of function. Hypomorphic Asns mutant mice have structural brain abnormalities, including enlarged ventricles and reduced cortical thickness, and show deficits in learning and memory mimicking aspects of the patient phenotype. ASNS encodes asparagine synthetase, which catalyzes the synthesis of asparagine from glutamine and aspartate. The neurological impairment resulting from ASNS deficiency may be explained by asparagine depletion in the brain or by accumulation of aspartate/gluta-mate leading to enhanced excitability and neuronal damage. Our study thus indicates that asparagine synthesis is essential for the development and function of the brain but not for that of other organs