Adenine Insertion Research Articles

A novel homozygous mutation in RASGRP1 that predisposes to immune dysregulation and immunodeficiency associated with uncontrolled Epstein-Barr virus-induced B cell proliferation

BackgroundRASGRP1-deficiency results in an immune dysregulation and immunodeficiency that manifest as autoimmunity, lymphoproliferation, lymphopenia, defective T cell function, and increased incidence of Epstein-Bar Virus infections and lymphomas. ObjectiveTo investigate the mechanism of autoimmune hemolytic anemia and infections in a male patient of consanguineous parents from Lebanon. MethodsGenetic diagnosis was obtained using next generation and Sanger sequencing. Protein expression and phosphorylation were determined by immunoblotting. T and B cell development and function were studied by flow cytometry. Cytokine and immunoglobulin secretions were quantified by enzyme-linked immunosorbent assay. ResultsThe patient suffered from severe lymphopenia especially affecting the T cell compartment. Genetic analysis revealed a homozygous insertion of adenine at position 1396_1397 in RASGRP1 that abolished protein expression and downstream Ras signaling. T cells from the patient showed severe activation defects resulting in uncontrolled Epstein-Bar Virus-induced B cell proliferation. B cells from the patient were normal. ConclusionThis report expands the spectrum of mutations in patients with RasGRP1 deficiency, and provides evidence for the important role RasGRP1 plays in the ability of T cells to control Epstein-Bar Virus-induced B cell proliferation. Clinical implicationsFollowing diagnosis, the patient will be maintained on oral valganciclovir and monitored regularly for Epstein-Bar Virus infections to avoid the development of Epstein-Bar Virus- induced B cell lymphoma. He is also candidate for hematopoietic stem cell transplantation.

Sugarcane bagasse improved growth performance, digestive enzyme activity, microbial dynamics, and mRNA transcripts of immune-, growth, and antioxidant -related genes of Litopenaeus vannamei in a zero-water exchange system

Pacific white shrimp (Litopenaeus vannamei) were grown in a biofloc rearing systems with (control treatment) or without sugarcane bagasse (SB treatment), with 3 replicate systems per treatment. SB, is an economic carbohydrate source. Parameters monitored were water-quality, growth indices, digestive enzymes activity, and microbial dynamics. Messenger RNA levels of immune-related, growth-related, and antioxidant genes in hepatopancreas and muscle and gene's single nucleotide polymorphism (SNP) were also considered. The outdoor ponds (44.5 m3), were each stocked with 600 L. vannamei larvae with an initial weight of 0.024 g) to start a three-month experiment. The biofloc development was in two aerated active suspension tanks to which SB (about 700 g/day, adjusted every two weeks) was added to maintain the of the C/N at 16. The water quality parameters, digestive enzyme activity, growth, and survival (P ≤ 0.05) in the SB group was improved compared to the control. SB also increased the total heterotrophic microbiota compared to the control. The mRNA levels of immune- related genes (lipopolysaccharides/b-glucan- binding protein, β-glucan-binding protein, lysozyme, prophenoloxidase, crustin, transglutaminase, and hemocyanin) and antioxidant genes (superoxide dismutase and glutathione peroxidase) significantly increased in SB group (P ≤ 0.05) compared to the control treatment. The SB group was the highest in all growth- related genes such as insulin- like growth factors (I and II), growth hormone, myosin, and paramyosin. Eight SNPs were detected in the hemocyanin gene, and an adenine insertion (ins A-554) was recorded at a high body weight. Our findings implied that using SB, as a carbon source in biofloc system without artificial feeding, could improve water quality, growth indices, digestive enzymes, microbial dynamics and the mRNA levels of all immune-, growth- related and antioxidant genes in L. vannamei.

Quantitative Analysis of RNA Polymerase Slippages for Production of P3N-PIPO Trans-frame Fusion Proteins in Potyvirids.

Potyvirids, members of the family Potyviridae, produce the P3N-PIPO protein, which is crucial for the cell-to-cell transport of viral genomic RNAs. The production of P3N-PIPO requires an adenine (A) insertion caused by RNA polymerase slippage at a conserved GAAAAAA (GA6) sequence preceding the PIPO open reading frame. Presently, the slippage rate of RNA polymerase has been estimated in only a few potyvirids, ranging from 0.8 to 2.1%. In this study, we analyzed publicly available plant RNA-seq data and identified 19 genome contigs from 13 distinct potyvirids. We further investigated the RNA polymerase slippage rates at the GA6 motif. Our analysis revealed that the frequency of the A insertion variant ranges from 0.53 to 4.07% in 11 potyviruses (genus Potyvirus). For the two macluraviruses (genus Macluravirus), the frequency of the A insertion variant was found to be 0.72% and 10.96% respectively. Notably, the estimated RNA polymerase slippage rates for 12 out of the 13 investigated potyvirids were reported for the first time in this study. Our findings underscore the value of plant RNA-seq data for quantitative analysis of potyvirid genome variants, specifically at the GA6 slippage site, and contribute to a more comprehensive understanding of the RNA polymerase slippage phenomenon in potyvirids.

Identifying a novel frameshift pathogenic variant in a Chinese family with neurofibromatosis type 1 and review of literature.

To detect the pathogenic gene variant in a family with neurofibromatosis type 1 (NF1). This patient with NF1 was sequenced using target sequence capture and high-throughput sequencing technology. After detecting the suspicious pathogenic variant type, the pathogenic variant sites of the patient and the patient's family members were verified by multiple ligation dependent probe amplification and Sanger sequencing. Sift, polyphen-2, Mutation Taster and GERP++ software were used to predict the pathogenicity of the unknown loci. The clinical data, diagnosis and treatment process of the patients were reviewed. Using the keyword "NF1; frameshift pathogenic variant", relevant literature was gathered for analysis from Chinese and international databases, with articles dating from the establishment of each database to April 2022. A heterozygous frameshift pathogenic variant of NF1 in exon 33 was detected in the patient. The insertion of adenine in coding region 4486 resulted in the replacement of isoleucine with asparagine in protein 1497. Sanger sequencing validation and segregation analysis were performed, which demonstrated that the NF1 gene was cosegregated with the disease phenotype in this family. This study identified a novel NF1 heterozygous frameshift mutation c.4486dupA (p.I1497Nfs*12). Relevant literature retrieval found 7 Chinese articles and 12 foreign articles. With NF1 gene mutation, mutation types are diverse, including point mutation, frameshift mutation, splice site mutation, exon mutation, chimeric mutation and de novo mutation. Foreign reports are based on autosomal dominant inheritance. This study's results demonstrate that a novel deletion in exon 33 caused NF1 in this Chinese family, expanding the mutational spectrum of the NF1 gene.

Associations of + 138 Ins/del A and + 5665 G/T polymorphisms of endothelin-1 gene with hypertension in Burmese people in Magway, Myanmar

BackgroundHypertension is one of the major public health problems worldwide, and is one of the recognized causes of premature deaths every year in the world. The purpose of this study was to investigate the associations between the + 138 insertion/deletion of adenine (Ins/del A) and + 5665 guanine-to-thymine (G/T) polymorphisms of the endothelin-1 gene and hypertension in the residents of Magway Township, Myanmar.MethodsThis study was a cross-sectional comparative study including 60 hypertensive patients and 60 control subjects in Magway Township, Myanmar. The inclusion criterion for hypertension was blood pressure ≥ 140/90 mmHg or previous diagnosis by a physician as hypertension and/or taking antihypertensive drugs. The control group had blood pressure < 140/90 mmHg and no previous diagnosis of hypertension. The genotyping was done by polymerase chain reaction and restriction fragment length polymorphism method.ResultsIn this study, the genotype distribution of the + 138 Ins/del A variant was significantly different between hypertensive patients and the control group, especially in the 3A4A genotype (odds ratio [OR], 2.451; 95% confidence interval [CI], 1.138–5.280; P = 0.022). Adenine insertion genotypes (3A4A and 4A4A) were significantly associated with hypertension in the dominant model (OR, 2.494; 95% CI, 1.179–5.276; P = 0.017). In addition, there was a significant association between the 4A allele and hypertension (OR, 1.771; 95% CI, 1.026–3.056; P = 0.040). The genotype and allelic distributions of the + 5665 G/T polymorphism were not significantly different between the hypertensive patients and the control group (P > 0.05). In this study, there was no significant association between the genotype and allele frequency, and hypertension (P > 0.05). The linkage disequilibrium was weak between the + 138 Ins/del A and + 5665 G/T loci (D’ = 0.108, r2 = 0.009).ConclusionsThis study provides evidence that the + 138 Ins/del A rather than + 5665 G/T polymorphism is associated with hypertension in Burmese people.

Insertion Mutation of MSMEG_0392 Play an Important Role in Resistance of M. smegmatis to Mycobacteriophage SWU1.

PurposePhage is a new choice for the treatment of multi-drug-resistant bacteria, and phage resistance is also an issue of concern. SWU1 is a mycobacteriophage, and the mechanism of its resistance remain poorly understood.MethodsThe mutant strains which were stably resistant to SWU1 were screened by transposon mutation library. The stage of phage resistance was observed by transmission electron microscope (TEM). The insertion site of transposon was identified by thermal asymmetric interlaced PCR (TAIL-PCR). The possible relationship between insertion site and phage resistance was verified by gene knockout technique. The fatty acid composition of bacterial cell wall was analyzed by Gas Chromatography-Mass Spectrometer (GC-MS). Through the amplification and sequencing of target genes and gene complement techniques to find the mechanism of SWU1 resistance.ResultsThe transposon mutant M12 which was stably resistant to mycobacteriophage SWU1 was successfully screened. It was confirmed that resistance occurred in the adsorption stage of bacteriophage. It was verified that the insertion site of the transposon was located in the MSMEG_3705 gene, but after knocking out the gene in the wild type M. smegmatis mc2 155, the resistance of the knockout strain to SWU1 was not observed. Through the amplification and sequencing of the target gene MSMEG_0392, it was found that there was an adenine insertion mutation at position 817. After complementing MSMEG_0392 in M12, it was found that M12 returned to sensitivity to SWU1.ConclusionWe confirmed that the resistance of M12 to SWU1 was related to the functional inactivation of MSMEG_0392 and this phenomenon may be caused by the change of cell wall of M. smegmatis.

Immobilization of Cyanines in DNA Produces Systematic Increases in Fluorescence Intensity.

Cyanines are useful fluorophores for a myriad of biological labeling applications, but their interactions with biomolecules are unpredictable. Cyanine fluorescence intensity can be highly variable due to complex photoisomerization kinetics, which are exceedingly sensitive to the surrounding environment. This introduces large errors in Förster resonance energy transfer (FRET)-based experiments where fluorescence intensity is the output parameter. However, this environmental sensitivity is a strength from a biological sensing point of view if specific relationships between biomolecular structure and cyanine photophysics can be identified. We describe a set of DNA structures that modulate cyanine fluorescence intensity through the insertion of adenine or thymine bases. These structures simultaneously provide photophysical predictability and tunability. We characterize these structures using steady-state fluorescence measurements, fluorescence correlation spectroscopy (FCS), and time-resolved photoluminescence (TRPL). We find that the photoisomerization rate decreases over an order of magnitude across the adenine series, which is consistent with increasing immobilization of the cyanine moiety by the surrounding DNA structure.

Characterization of tomato leaf mould pathogen, Passalora fulva, in Croatia

Leaf mould (Passalora fulva) has emerged as an important disease of greenhouse-growing tomato crops in Croatia during the last decade. In order to establish sustainable control measures, the presence of P. fulva races was investigated, in vitro sensitivity of the fungus to several fungicidal products was tested, and susceptibility of some old tomato varieties was checked. Seventeen isolates were collected from different parts of Croatia and inoculated on tomato cv. ‘Moneymaker’ differentials with different resistance genes (Cf-2, Cf-4, Cf-5 and Cf-9) or without resistance genes (Cf-0). Based on symptoms appearance assessment, 11 isolates were determined as P. fulva race 2, two isolates as race 5, one isolate as race 2.5 and three isolate as race 0. Sequence analysis of the Avr2 gene of five P. fulva race 2 isolates showed and insertion of adenine at 117_119 bp compared to the reference Avr2 wild-type gene retrieved from GenBank®, which leads to amino acid change from Tyrosine to Valine (p. Tyr41ValfsX1) in Avr2 protein. Pathogenicity tests with a P. fulva race 2 isolate on seven old tomato varieties lead to the development of leaf mould symptoms on four of seven varieties. Sensitivity of a selected P. fulva race 2 isolate was examined on agar plates amended with four fungicides products which were authorized in Croatia at that time for control different diseases on tomato. According to the results, Signum® was significantly and constantly the most effective product across all assessment periods.

Correction of frameshift mutations in the atpB gene by translational recoding in chloroplasts of Oenothera and tobacco.

Translational recoding, also known as ribosomal frameshifting, is a process that causes ribosome slippage along the messenger RNA, thereby changing the amino acid sequence of the synthesized protein. Whether the chloroplast employs recoding is unknown. I-iota, a plastome mutant of Oenothera (evening primrose), carries a single adenine insertion in an oligoA stretch [11A] of the atpB coding region (encoding the β-subunit of the ATP synthase). The mutation is expected to cause synthesis of a truncated, nonfunctional protein. We report that a full-length AtpB protein is detectable in I-iota leaves, suggesting operation of a recoding mechanism. To characterize the phenomenon, we generated transplastomic tobacco lines in which the atpB reading frame was altered by insertions or deletions in the oligoA motif. We observed that insertion of two adenines was more efficiently corrected than insertion of a single adenine, or deletion of one or two adenines. We further show that homopolymeric composition of the oligoA stretch is essential for recoding, as an additional replacement of AAA lysine codon by AAG resulted in an albino phenotype. Our work provides evidence for the operation of translational recoding in chloroplasts. Recoding enables correction of frameshift mutations and can restore photoautotrophic growth in the presence of a mutation that otherwise would be lethal.

A common CORIN variant in hypertension reduces corin intracellular trafficking by exposing an inhibitory N-terminus

Corin is a transmembrane serine protease that activates atrial natriuretic peptide, a cardiac hormone essential for normal blood pressure. Corin is synthesized as a zymogen and activated on the cell surface. In previous studies, we identified a CORIN variant allele with an adenine insertion in the 5′-end of the coding region in ∼5% of hypertensive individuals in a Chinese population. The protein, named insA, encoded by the CORIN variant allele has a shortened cytoplasmic tail and reduced atrial natriuretic peptide processing activity. It remains unknown how a shortened cytoplasmic tail impairs corin function. In this study, we expressed a series of corin mutants with different N-terminal sequences and analyzed them by Western blotting, flow cytometry, protein chase, and immunostaining. Our results revealed that a Gly-Asn sequence after the initiating Met at the newly generated N-terminus was responsible for delaying corin trafficking in the Golgi. Deletion of the N-terminal Gly and Asn residues increased the intracellular trafficking, cell surface expression, and activation cleavage of the insA variant. These results help to explain how the CORIN variant allele impairs corin structure and function as an underlying mechanism in hypertension.

Predictable CRISPR/Cas9-Mediated COL7A1 Reframing for Dystrophic Epidermolysis Bullosa

End-joining‒based gene editing is frequently used for efficient reframing and knockout of target genes. However, the associated random, unpredictable, and often heterogeneous repair outcomes limit its applicability for therapeutic approaches. This study revealed more precise and predictable outcomes simply on the basis of the sequence context at the CRISPR/Cas9 target site. The severe dystrophic form of the blistering skin disease epidermolysis bullosa (DEB) represents a suitable model platform to test these recent developments for the disruption and reframing of dominant and recessive alleles, respectively, both frequently seen in DEB. We delivered a CRISPR/Cas9 nuclease as ribonucleoprotein into primary wild-type and recessive DEB keratinocytes to introduce a precise predictable single adenine sense-strand insertion at the target site. We achieved type VII collagen knockout in more than 40% of ribonucleoprotein-treated primary wild-type keratinocytes and type VII collagen restoration in more than 70% of ribonucleoprotein-treated recessive DEB keratinocytes. Next-generation sequencing of the on-target site revealed the presence of the precise adenine insertion upstream of the pathogenic mutation in at least 17% of all analyzed COL7A1 alleles. This demonstrates that COL7A1 editing based on precise end-joining‒mediated DNA repair is an efficient strategy to revert the disease-associated nature of DEB regardless of the mutational inheritance.

Development and Validation of a Scoring System, Based on Genetic and Clinical Factors, to Determine Risk of Steatohepatitis in Asian Patients with Nonalcoholic Fatty Liver Disease

There are no biomarkers of nonalcoholic steatohepatitis (NASH) that are ready for routine clinical use. We investigated whether an analysis of PNPLA3 and TM6SF2 genotypes (rs738409 and rs58542926) can be used to identify patients with nonalcoholic fatty liver disease (NAFLD), with and without diabetes, who also have NASH. We collected data from the Boramae registry in Korea on 453 patients with biopsy-proven NAFLD with sufficient clinical data for calculating scores. Patients enrolled from February 2014 through March 2016 were assigned to cohort 1 (n= 302; discovery cohort) and patients enrolled thereafter were assigned to cohort 2 (n= 151; validation cohort). DNA samples were obtained from all participants and analyzed for the PNPLA3 rs738409 C>G, TM6SF2 rs58542926 C>T, SREBF2 rs133291 C>T, MBOAT7-TMC4 rs641738 C>T, and HSD17B13 rs72613567 adenine insertion (A-INS) polymorphisms. We used multivariable logistic regression analyses with stepwise backward selection to build a model to determine patients' risk for NASH (NASH PT) using the genotype and clinical data from cohort 1 and tested its accuracy in cohort 2. We used the receiver operating characteristic (ROC) curve to compare the diagnostic performances of the NASH PT and the NASH scoring systems. We developed a NASH PT scoring system based on PNPLA3 and TM6SF2 genotypes, diabetes status, insulin resistance, and levels of aspartate aminotransferase and high-sensitivity C-reactive protein. NASH PT scores identified patients with NASH with an area under the ROC (AUROC) of 0.859 (95%CI, 0.817-0.901) in cohort 1. In cohort 2, NASH PT scores identified patients with NASH with an AUROC of 0.787 (95% CI, 0.715-0.860), which was significantly higher than the AUROC of the NASH score (AUROC, 0.729; 95% CI, 0.647-0.812; P= .007). The AUROC of the NASH PT score for detecting NASH in patients with NAFLD with diabetes was 0.835 (95% CI, 0.776-0.895) and in patients without diabetes was 0.809 (95% CI, 0.757-0.861). The negative predictive value of the NASH PT score <-0.785 for NASH in patients with NAFLD with diabetes reached 0.905. We developed a scoring system, based on polymorphisms in PNPLA3 and TM6SF2 and clinical factors that identifies patients with NAFLD, with or without diabetes, who have NASH, with an AUROC value of 0.787. This system might help clinicians better identify NAFLD patients at risk for NASH.

The Short Communication: Polymorphism of myostatin gene and its association with body weight traits in a hybrid of GAMA chicken (Gallus gallus domesticus Linn. 1758)

Abstract. Tanjung A, Saragih HTSSG, Trijoko, Soenarwan HP, Widianto S, Mahardhika IWS, Daryono BS. 2019. Polymorphism of myostatin gene and its association with body weight traits in a hybrid of GAMA chicken (Gallus gallus domesticus Linn. 1758). Biodiversitas 20: 3207-3212. An experiment was conducted to detect SNP of the myostatin gene and its association with the body weight of hybrid chicken crossbreed from F1 Kamper and BC1 Broiler. Four F1 Kamper hens were crossbred with BC1 Broiler rooster. Day old chick (DOC) hatched were maintained for 49 days with body weight measurement every seven days. The blood samples from 49 days old chicken were taken for DNA isolation by Chelex 5% method and then amplification of the myostatin gene. PCR products were sequenced, and sequence alignment was performed using Clustal Omega to obtain SNP. The SNP obtained was analyzed by the Pearson correlation test with the body weight of forty nine-days-old chickens. The body weight of the hybrid chicken is higher than of Pelung chicken but lower than the Broiler. There are 7 SNPs in myostatin gene exons included 2 Adenine insertions, 1 Guanine deletion, and four substitutions (C2244G, G2283A, T4842G, G7378T) that yield nine haplotypes. Six haplotypes had different protein sequences with Myostatin protein, while three haplotypes were identical to Myostatin protein. The correlation analysis showed that there was a strong positive correlation (r = 0.736) between normal Myostatin protein and mutant to chicken body weight at 49-days-old. Adenine insertion to nucleotide 2099-2100 of myostatin gene had a very strong positive correlation (r = 0.800) to 49-days-old chicken body weight, although T4842G substitution had a strong negative relationship (r = -0.773) to 49-days-old chicken body weight. Adenine insertion to nucleotide 2099-2100 of myostatin gene could be a genetic marker of heavier body weight of the hybrid chicken.

Transcriptional Fidelity of Mitochondrial RNA Polymerase RpoTm from Arabidopsis thaliana

Fidelity of RNA synthesis is essential for the faithful transfer of information from DNA to RNA. A comprehensive analysis of the nucleotide selectivity by the mitochondrial RNA polymerase (RNAP) RpoTm, from Arabidopsis thaliana, has been carried out. The kinetic parameters for the incorporation of cognate, noncognate, and oxidized bases have been determined. The results establish high fidelity of mitochondrial transcription resembling those of replicative polymerases in the absence of repair. In addition, RpoTm incorporates oxidized nucleotides with similar efficiency compared with mismatches and is capable of extending the RNA beyond the insertion of the oxidized base. Furthermore, lesion bypass study on RpoTm demonstrates that the enzyme bypasses 8-oxo-guanine by insertion of adenine leading to C to A mutations in RNA. Homology modeling of RpoTm elongation complex allows delineation of the residues necessary for stabilizing the incoming NTP substrate and for posing the template nucleotide residue. Substitution of these residues leads to compromise in the activity of the enzyme corroborating their importance in RNA synthesis. Comparison of the data with T7 RNAPs indicates that low efficiency of misincorporation is a universal strategy used by single-subunit RNAPs for maintaining high fidelity in the absence of proofreading and repair activity in mitochondria.

Unexpected behavior of DNA polymerase Mu opposite template 8-oxo-7,8-dihydro-2'-guanosine.

DNA double-strand breaks (DSBs) resulting from reactive oxygen species generated by exposure to UV and ionizing radiation are characterized by clusters of lesions near break sites. Such complex DSBs are repaired slowly, and their persistence can have severe consequences for human health. We have therefore probed DNA break repair containing a template 8-oxo-7,8-dihydro-2'-guanosine (8OG) by Family X Polymerase μ (Pol μ) in steady-state kinetics and cell-based assays. Pol μ tolerates 8OG-containing template DNA substrates, and the filled products can be subsequently ligated by DNA Ligase IV during Nonhomologous end-joining. Furthermore, Pol μ exhibits a strong preference for mutagenic bypass of 8OG by insertion of adenine. Crystal structures reveal that the template 8OG is accommodated in the Pol μ active site with none of the DNA substrate distortions observed for Family X siblings Pols β or λ. Kinetic characterization of template 8OG bypass indicates that Pol μ inserts adenosine nucleotides with weak sugar selectivity and, given the high cellular concentration of ATP, likely performs its role in repair of complex 8OG-containing DSBs using ribonucleotides.

Editing of Rice Isoamylase Gene ISA1 Provides Insights into Its Function in Starch Formation

Isoamylase 1 (ISA1) is an isoamylase-type debranching enzyme which plays a predominant role in amylopectin synthesis. In this study, the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated endonuclease 9 (CRISPR/Cas9) system was used to edit ISA1 gene in rice via Agrobacterium-mediated transformation. We identified 36 genetic edited lines from 55 T0 transgenic events, and classified the mutation forms into 7 types. Of those, two homozygous mutants, cr-isa1-1 (type 1, with an adenine insertion) and cr-isa1-2 (type 3, with a cytosine deletion) were selected for further analysis. Seed sizes of both cr-isa1-1 and cr-isa1-2 were affected, and the two mutants also displayed a shrunken endosperm with significantly lower grain weight. Electron microscopy analysis showed that abnormal starch granules and amyloplasts were found in cr-isa1-1 and cr-isa1-2 endosperm cells. The contents of total starch, amylose and amylopectin in the endosperm of the cr-isa1 mutants were significantly reduced, whereas sugar content and starch gel consistency were observably increased compared to the wild-type. The gelatinization temperature and starch chain length distributions of the cr-isa1 mutants were also altered. Moreover, transcript levels of most starch synthesis-related genes were significantly lower in cr-isa1 mutants. In conclusion, the results indicated that gene edition of ISA1 affected starch synthesis and endosperm development, and brought potential implications for rice quality breeding.

Splice variant rs72613567 prevents worst histologic outcomes in patients with nonalcoholic fatty liver disease

Hydroxysteroid 17-β dehydrogenase 13 (HSD17B13) is a lipid droplet-associated protein; its gene-encoding variants affect the chronic liver diseases, including nonalcoholic fatty liver disease (NAFLD). To estimate the effect of rs72613567, a splice variant with an adenine insertion (A-INS), on NAFLD susceptibility and severity, we performed a case-control study with 609 individuals. We investigated the effect of carrying the A-INS allele in 356 patients with biopsy-proven disease and explored the relationship between rs72613567 genotypes and the hepatic transcriptome. The A-INS allele protected against NAFLD [odds ratio (OR) per adenine allele = 0.667; 95% CI, 0.486-0.916; P = 0.012]; this effect was nonsignificant when logistic regression analysis included BMI. The A-INS allele protected against nonalcoholic steatohepatitis (NASH) (OR = 0.612; 95% CI, 0.388-0.964; P = 0.033), ballooning degeneration (OR = 0.474; 95% CI, 0.267-0.842; P = 0.01), lobular inflammation (OR = 0.475; 95% CI, 0.275-0.821; P = 0.007), and fibrosis (OR = 0.590; 95% CI, 0.361-0.965; P = 0.035). In patients carrying A-INS, HSD17B13 levels decreased proportionally to allele dosage. Whole-transcriptome genotype profiling showed overrepresented immune response-related pathways. Thus, the rs72613567 A-INS allele reduces the risk of NASH and progressive liver damage and may become a therapeutic target.

Recurrent tendosynovitis as a rare manifestation of a lipid disorder

A 33-year-old female had suffered from spontaneously recurrent bursitis and tendosynovitis/enthesitis of the patellar and Achilles tendons for about 10 years. The episodes of immobilization increased. Ultrasound imaging of the swollen and painful tendons showed chronic inflammation with neoangiogenesis within the tendons and hypoechoic lesions. Clinical and laboratory tests did not provide evidence for a rheumatic disease. Low density lipoprotein cholesterol was elevated. Biopsies of skin lesions did not confirm the suspicion of cutaneous xanthomas. Genetic testing for familial hypercholesterolemia was negative. Campesterol and sitosterol were elevated 7- to 12-fold and 20- to 38-fold over the upper limit of normal on two occasions. There was no relevant mutation in ABCG5. In ABCG8, we identified a missense mutation c.1267G>A in exon 9 changing glutamic acid 423 into lysine within the transmembrane domain, and an insertion of adenine (c.1487insA) leading to a frameshift and a premature stop codon (Ile497Aspfs*105). The patient had no clinical evidence of premature atherosclerosis. Therapeutic approaches with nonsteroidal antirheumatic drugs, prednisone, statins, and ezetimibe accompanied by a diet poor in plant sterols led to a relief of symptoms. This case report shows that tendon xanthoma along with tendosynovitis, especially on extensor areas, is suspicious for hypercholesterolemia as the underlying cause. The absence of atherosclerotic plaques in the abdominal aorta and in the carotid arteries on ultrasound may suggest that phytosterolemia is not necessarily accompanied by premature vascular disease.

A novel mutation of NFIX causes Sotos-like syndrome (Malan syndrome) complicated with thoracic aortic aneurysm and dissection

Malan syndrome has recently been characterized to present Sotos-like phenotypes, such as intellectual disability and macrocephaly, with mutations in the NFIX gene. Herein, we report a 38-year-old patient with a novel single adenine insertion mutation in exon 2 of the NFIX gene (c.290_291insA). He developed early-onset thoracic aortic aneurysm and dissection, which was a rare complication but deserves particular attention in relatively long-lived patients with Sotos-like phenotypes.

Germline and somatic genetic changes in multicentric tumors obtained from a patient with multiple endocrine neoplasia type 1

Multiple endocrine neoplasia type 1 (MEN1) is a hereditary cancer syndrome caused by germline mutations of the MEN1 gene located in chromosome 11q13. In patients with MEN1, multicentric tumors develop in the involved organs; however, precise evaluation of genetic changes in these multicentric tumors has not been performed. In the present study, using whole-exome sequencing, we analyzed germline and somatic genetic changes in blood cells, two pancreatic endocrine tumors and one duodenal tumor obtained from a patient with MEN1 gastrinoma. We found that this patient possessed a novel germline mutation of the MEN1 gene [NM_137099.2:c.1505dupA (p.Lys502Lysfs); the localization was Chr11:64572134 on Assembly GRCh37], in which an adenine insertion in codon 502 of the MEN1 gene resulted in a frame shift and a premature stop codon. In terms of heterozygosity, the mutated allele was heterozygous in blood cells, hemizygous in the two pancreatic tumors and homozygous in the duodenal tumor. Immunohistochemical staining confirmed that only truncated menin protein accumulated in the nucleus of the tumor tissues. Further evaluation of tumor-specific somatic mutations in two pancreatic tumors did not detect single-nucleotide variations (SNVs) in 609 cancer-associated genes designated by the COSMIC cancer gene census, suggesting that the germline MEN1 mutation and resultant loss of heterozygosity played a major role in tumorigenesis. In the duodenal tumor, in addition to the germline MEN1 mutation, single-nucleotide variations in two cancer-associated genes were found. Further studies are required to clarify the role of these somatic single-nucleotide variations in the progression of MEN1 tumors.