Heterozygous deletions of noncoding parts of the PRPF31 gene cause retinitis pigmentosa via reduced gene expression.

Purpose: Heterozygous mutations in the gene PRPF31, encoding a pre-mRNA splicing factor, cause autosomal dominant retinitis pigmentosa (adRP) with reduced penetrance. At the molecular level, pathogenicity results from haploinsufficiency, as the largest majority of such mutations trigger nonsense-mediated mRNA decay or involve large deletions of coding exons. We investigated genetically two families with a history of adRP, one of whom showed incomplete penetrance. Methods: All patients underwent thorough ophthalmological examination, including electroretinography (ERG) and Goldmann perimetry. Array-based comparative genomic hybridization (aCGH) and multiplex ligation-dependent probe amplification (MLPA) were used to map heterozygous deletions, while real-time PCR on genomic DNA and long-range PCR allowed resolving the mutations at the base-pair level. PRPF31 transcripts were quantified with real-time PCR on patient-derived lymphoblastoid cell lines. Results: We identified two independent deletions affecting the promoter and the 5' untranslated region (UTR) of PRPF31 but leaving its coding sequence completely unaltered. Analysis of PRPF31 mRNA from lymphoblastoid cell lines from one of these families showed reduced levels of expression in patients versus controls, probably due to the heterozygous ablation of its promoter sequences. Conclusions: In addition to reporting the identification of two novel noncoding deletions in PRPF31, this study provides strong additional evidence that mRNA-mediated haploinsufficiency is the primary cause of pathogenesis for PRPF31-linked adRP.

Non-coding deletions identify Maenli lncRNA as a limb-specific En1 regulator.

Long non-coding RNAs (lncRNAs) can be important components in gene-regulatory networks1, but the exact nature and extent of their involvement in human Mendelian disease is largely unknown. Here we show that genetic ablation of a lncRNA locus on human chromosome 2 causes a severe congenital limb malformation. We identified homozygous 27-63-kilobase deletions located 300 kilobases upstream of the engrailed-1 gene (EN1) in patients with a complex limb malformation featuring mesomelic shortening, syndactyly and ventral nails (dorsal dimelia). Re-engineering of the human deletions in mice resulted in a complete loss of En1 expression in the limb and a double dorsal-limb phenotype that recapitulates the human disease phenotype. Genome-wide transcriptome analysis in the developing mouse limb revealed a four-exon-long non-coding transcript within the deleted region, which we named Maenli. Functional dissection of the Maenli locus showed that its transcriptional activity is required for limb-specific En1 activation in cis, thereby fine-tuning the gene-regulatory networks controlling dorso-ventral polarity in the developing limb bud. Its loss results in the En1-related dorsal ventral limb phenotype, a subset of the full En1-associated phenotype. Our findings demonstrate that mutations involving lncRNA loci can result in human Mendelian disease.

Clinical Impact of 5 Years of Liraglutide Treatment on Cardiovascular Risk Factors in Patients with Type 2 Diabetes Mellitus in a Real-Life Setting in Italy: An Observational Study.

INTRODUCTION: Based on existing data regarding the durability of liraglutide in type 2 diabetes, this study aimed to assess its long-term effectiveness at 5 years and its overall impact on cardiovascular (CV) risk. METHODS: This was a multicenter retrospective observational study. Liraglutide was used under routine clinical practice conditions. Changes from baseline to 60 months in HbA1c, fasting plasma glucose (FPG), body weight, blood pressure, and lipid profile were assessed. United Kingdom Prospective Diabetes Study (UKPDS) scores were calculated at baseline and after 60 months to assess changes in the estimated 5- and 10-year risk for fatal and nonfatal coronary heart disease (CHD) and fatal and nonfatal stroke. RESULTS: Overall, 103 patients (age 59.0 ± 7.9 years, diabetes duration 10.4 ± 6.8 years) were involved in the study. After 60 months, HbA1c levels were reduced by - 1.0 ± 1.2%, FPG levels by - 24.5 ± 43.4 mg/dl, body weight by - 5.3 ± 6.4 kg, systolic blood pressure by - 6.5 ± 18.5 mmHg, diastolic blood pressure by - 3.6 ± 11.8 mmHg, and total cholesterol by - 16.9 ± 37.4 mg/dl. The proportion of patients achieving HbA1c levels of < 7% increased from 12.7% to 39.8% (p = 0.02). Based on the UKPDS scores, statistically significant reductions in the 5- and 10-year risk of nonfatal CHD and fatal CHD were found, with no change in the 5- and 10-year risk of fatal and nonfatal stroke. CONCLUSION: In patients prolonging treatment with liraglutide for 5 years, the benefits in relation to metabolic control and CV risk factors are maintained. The UKPDS risk scores suggest that liraglutide is associated with a reduced CHD risk, but not with a reduced stroke risk.

Mutations in CEP78 Cause Cone-Rod Dystrophy and Hearing Loss Associated with Primary-Cilia Defects.

Cone-rod degeneration (CRD) belongs to the disease spectrum of retinal degenerations, a group of hereditary disorders characterized by an extreme clinical and genetic heterogeneity. It mainly differentiates from other retinal dystrophies, and in particular from the more frequent disease retinitis pigmentosa, because cone photoreceptors degenerate at a higher rate than rod photoreceptors, causing severe deficiency of central vision. After exome analysis of a cohort of individuals with CRD, we identified biallelic mutations in the orphan gene CEP78 in three subjects from two families: one from Greece and another from Sweden. The Greek subject, from the island of Crete, was homozygous for the c.499+1G>T (IVS3+1G>T) mutation in intron 3. The Swedish subjects, two siblings, were compound heterozygotes for the nearby mutation c.499+5G>A (IVS3+5G>A) and for the frameshift-causing variant c.633delC (p.Trp212Glyfs(∗)18). In addition to CRD, these three individuals had hearing loss or hearing deficit. Immunostaining highlighted the presence of CEP78 in the inner segments of retinal photoreceptors, predominantly of cones, and at the base of the primary cilium of fibroblasts. Interaction studies also showed that CEP78 binds to FAM161A, another ciliary protein associated with retinal degeneration. Finally, analysis of skin fibroblasts derived from affected individuals revealed abnormal ciliary morphology, as compared to that of control cells. Altogether, our data strongly suggest that mutations in CEP78 cause a previously undescribed clinical entity of a ciliary nature characterized by blindness and deafness but clearly distinct from Usher syndrome, a condition for which visual impairment is due to retinitis pigmentosa.

NANS-mediated synthesis of sialic acid is required for brain and skeletal development.

We identified biallelic mutations in NANS, the gene encoding the synthase for N-acetylneuraminic acid (NeuNAc; sialic acid), in nine individuals with infantile-onset severe developmental delay and skeletal dysplasia. Patient body fluids showed an elevation in N-acetyl-D-mannosamine levels, and patient-derived fibroblasts had reduced NANS activity and were unable to incorporate sialic acid precursors into sialylated glycoproteins. Knockdown of nansa in zebrafish embryos resulted in abnormal skeletal development, and exogenously added sialic acid partially rescued the skeletal phenotype. Thus, NANS-mediated synthesis of sialic acid is required for early brain development and skeletal growth. Normal sialylation of plasma proteins was observed in spite of NANS deficiency. Exploration of endogenous synthesis, nutritional absorption, and rescue pathways for sialic acid in different tissues and developmental phases is warranted to design therapeutic strategies to counteract NANS deficiency and to shed light on sialic acid metabolism and its implications for human nutrition.

Mutations in the polyglutamylase gene TTLL5, expressed in photoreceptor cells and spermatozoa, are associated with cone-rod degeneration and reduced male fertility.

Hereditary retinal degenerations encompass a group of genetic diseases characterized by extreme clinical variability. Following next-generation sequencing and autozygome-based screening of patients presenting with a peculiar, recessive form of cone-dominated retinopathy, we identified five homozygous variants [p.(Asp594fs), p.(Gln117*), p.(Met712fs), p.(Ile756Phe), and p.(Glu543Lys)] in the polyglutamylase-encoding gene TTLL5, in eight patients from six families. The two male patients carrying truncating TTLL5 variants also displayed a substantial reduction in sperm motility and infertility, whereas those carrying missense changes were fertile. Defects in this polyglutamylase in humans have recently been associated with cone photoreceptor dystrophy, while mouse models carrying truncating mutations in the same gene also display reduced fertility in male animals. We examined the expression levels of TTLL5 in various human tissues and determined that this gene has multiple viable isoforms, being highly expressed in testis and retina. In addition, antibodies against TTLL5 stained the basal body of photoreceptor cells in rat and the centrosome of the spermatozoon flagellum in humans, suggesting a common mechanism of action in these two cell types. Taken together, our data indicate that mutations in TTLL5 delineate a novel, allele-specific syndrome causing defects in two as yet pathogenically unrelated functions, reproduction and vision.

Short stature and primary ovarian insufficiency possibly due to chromosomal position effect in a balanced X;1 translocation.

BACKGROUND: Primary ovarian insufficiency (POI) is defined as a primary ovarian defect characterized by absent menarche (primary amenorrhea), a decrease in the initial primordial follicle number, high follicle-stimulating hormone (FSH) levels and hypoestrogenism. Although the etiology of a majority of POI cases is not yet identified, several data suggest that POI has a strong genetic component. Conventional cytogenetic and molecular analyses have identified regions of the X chromosome that are associated with ovarian function, as well as POI candidate genes, such as FMR1 and DIAPH2. Here we describe a 10.5-year-old girl presenting with high FSH and luteinizing hormone (LH) levels, pathologic GH stimulation arginine and clonidine tests, short stature, pterygium, ovarian dysgenesis, hirsutism and POI. RESULTS: Cytogenetic analysis demonstrated a balanced reciprocal translocation between the q arms of chromosomes X and 1, with breakpoints falling in Xq21 and 1q41 bands. Molecular studies did not unravel any chromosome microdeletion/microduplication, and no XIST-mediated inactivation was found on the derivative chromosome 1. Interestingly, through immunofluorescence assays, we found that part of the Xq21q22 trait, translocated to chromosome 1q41, was late replicating and therefore possibly inactivated in 30 % metaphases both in lymphocytes and skin fibroblasts, in addition to a skewed 100 % inactivation of the normal X chromosome. These findings suggest that a dysregulation of gene expression might occur in this region. Two genes mapping to the Xq translocated region, namely DIAPH2 and FMR1, were found overexpressed if compared with controls. CONCLUSIONS: We report a case in which gonadal dysgenesis and POI are associated with over-expression of DIAPH2 gene and of FMR1 gene in wild type form. We hypothesize that this over-expression is possibly due to a phenomenon known as "chromosomal position effect", which accounts for gene expression variations depending on their localization within the nucleus. For the same effect a double mosaic inactivation of genes mapping to the Xq21-q22 region, demonstrated by immunofluorescence assays, may be the cause of a functional Xq partial monosomy leading to most Turner traits of the proband's phenotype.

Correlation between baseline characteristics and clinical outcomes in a large population of diabetes patients treated with liraglutide in a real-world setting in Italy.

PURPOSE: Treatment with liraglutide in randomized controlled trials is associated with significant reductions in glycated hemoglobin (HbA1c) and weight loss in type 2 diabetes patients. The aim of this retrospective observational study was to investigate correlations of glycemic control and weight outcomes with baseline characteristics of patients starting liraglutide in outpatient clinics in Italy. METHODS: Type 2 diabetes patients were followed from baseline to 4, 8, and 12 months. Changes in glycemic parameters, weight, blood pressure, and lipids were assessed. Subanalyses were performed according to baseline characteristics. Multivariate linear and logistic regressions were used to assess correlations between glycemic efficacy, weight reduction, and liraglutide discontinuation after 12 months and baseline characteristics. FINDINGS: Four hundred and eighty-one patients were included. Mean (SD) age at baseline was 57.3 (9.2) years, diabetes duration was 9.5 (6.8) years, weight was 106.7 (20.8) kg, body mass index (BMI; calculated as kg/m(2)) was 37.1 (6.6), HbA1c was 8.7% (1.3%), fasting plasma glucose was 168.5 (45.3) mg/dL; 38.2% were treated previously with insulin and 52.2% were treated with metformin alone. After 12 months, mean (SD) changes were HbA1c -1.2% (1.4%), fasting plasma glucose -28.3 (41.1) mg/dL, weight -3.5 (5.8) kg, BMI -1.3 (2.1), waist circumference -2.6 (6.7) cm (all, P < 0.001). Drop in weight and HbA1c did not differ between baseline BMI classes ≤30 or >30. Weight loss was unchanged among diabetes duration quartiles, and HbA1c reduction was significantly greater in patients with ≤4 years of diabetes duration (P = 0.01). Non-insulin-treated patients reached HbA1c ≤7% significantly more often than treated patients (44.2% vs 21.2%; odds ratio = 2.94; P < 0.001) and had significantly greater weight loss (-4.5 [8.2] kg vs -2.6 [5.4] kg; P = 0.03). Patients on metformin reached HbA1c target more frequently than others (43.1% vs 29.7%; odds ratio = 1.80; 95% CI, 1.05-3.07). Significant positive determinants for HbA1c reduction after 12 months were baseline HbA1c, age, and prior metformin monotherapy, and weight loss at 12 months was positively correlated with baseline weight, and negatively correlated with prior insulin treatment. Overall, 5.0% of patients interrupted liraglutide before the 12th month due to lack of glycemic control; they were less frequently treated with metformin only before liraglutide (29.2% vs 50.2%; P = 0.04). IMPLICATIONS: Treatment with liraglutide in a real-world setting is associated with low therapy failure, good glycemic response, weight loss, and improvement in systolic blood pressure and lipid profile. The HbA1c drop did not differ among baseline BMI classes, indicating that efficacy is maintained in patients with lower BMI. The probability of reaching HbA1c ≤7% was significantly higher in patients previously treated with metformin alone and without any previous insulin. This could reinforce the hypothesis that better results with liraglutide could be achieved in patients after early metformin failure.

Insulin causes endothelial dysfunction in humans: sites and mechanisms.

BACKGROUND: Insulin resistance is often accompanied by hyperinsulinemia and may predispose to atherosclerosis. Endothelium plays a central role in atherogenesis. The in vivo effects of hyperinsulinemia on endothelial function of large conduit arteries are unknown. METHODS AND RESULTS: Twenty-five healthy subjects were enrolled for study. In study A (n=9), subjects underwent both a time-control saline study and a euglycemic low-dose insulin (insulin approximately 110 pmol/L) clamp for 6 hours. Study B (n=5) was identical to study A except that the euglycemic clamp was performed at high physiological insulin concentrations (approximately 440 pmol/L). In study C (n=7), subjects underwent two 4-hour euglycemic insulin (approximately 110 pmol/L) clamps with and without the concomitant infusion of an antioxidant (vitamin C). In study D (n=4), two saline time-control studies were performed with and without the concomitant infusion of vitamin C. In all studies, both at baseline and throughout the experimental period, endothelium-dependent (flow-mediated) and endothelium-independent (nitroglycerin-induced) vasodilation was assessed in femoral and brachial arteries by echo Doppler. Both low (study A) and high physiological (study B) hyperinsulinemia abolished endothelium-dependent vasodilation, whereas endothelium-independent vasodilation was unaffected. Vitamin C fully restored insulin-impaired endothelial function without affecting endothelium-independent vasodilation (study C). Vitamin C had no effects on endothelium-dependent or endothelium-independent vasodilation during saline control studies (study D). CONCLUSIONS: Modest hyperinsulinemia, mimicking fasting hyperinsulinemia of insulin-resistant states, abrogates endothelium-dependent vasodilation in large conduit arteries, probably by increasing oxidant stress. These data may provide a novel pathophysiological basis to the epidemiological link between hyperinsulinemia/insulin-resistance and atherosclerosis in humans.