Wolframin Gene Research Articles

1475-P: Novel Mutations in the Wolframin Gene with Diabetes—A Case Series of a Potential Addition to the Monogenic Diabetes Profile

Monogenic DM (MGDM) is a heterogeneous group of disorders caused by single gene mutations resulting in variable clinical phenotypes of diabetes mellitus (DM). While maturity onset diabetes of the young (MODY) remains the most known group, it is now recognized that there are other single gene defects associated with DM. Current MODY classification details 14 distinct genetic types which are mostly autosomal dominant (AD). We present a case series of 4 African-American (AA) men with novel mutations of the Wolframin (WS1) gene and type 2 DM (T2DM) phenotype. Patient 1 is a 54-yr-old AA man with presumed T2DM. Given his lack of family DM history, short DM duration, late onset and rapid renal functional decline, the possibility of atypical DM was considered. Genetic testing showed a heterozygous mutation of the WFS1 (wolframin gene); c.169 G>A, p.Ala57Thr. He had no other features of Wolfram’s syndrome; DIDMOAD (diabetes insipidus, DM, optic atrophy + deafness). Pts 2-4 are all family members. Pt 2 is a 65-yr-old AA man with new onset DKA and presumed T2DM. Given his initial DKA presentation, non-obese phenotype and absent family DM history, full phenotyping was done and genetic testing revealed a heterozygous mutation of the WFS1 gene; c.2385 G>C, p.Glu795Asp. He had no other features of DIDMOAD. Neither of his parents had DM and nor does his wife. He has 3 children (two sons and a daughter). Both sons (Pts 3-4), aged 41 and 36 yrs, have DM and both have the same WFS1 mutation. Both sons were diagnosed with DM before their father. The familial distribution suggests possible AD transmission. WFS1 mutations have a broad spectrum of phenotypes and inheritance patterns. Our case series with unique WFS1 mutations suggests a possible MGDM syndrome in subjects with heterozygous WFS1 mutations without DIDMOAD. Further functional analyses of WFS1 mutations associated with DM without DIDMOAD are needed to better understand their DM pathophysiology and inform best management strategies. Disclosure Z.Yin: None. A.A.Noor: None. K.G.Romo: None. S.Bhamre: None. M.Gabriel: None. T.Pulisetty: None. S.Shu: None. G.I.Uwaifo: None.

Next Generation Sequencing Analysis of MODY-X Patients: A Case Report Series.

Background: Classic criteria for a maturity-onset diabetes of the young (MODY) diagnosis are often unable to identify all subjects, and traditional Sanger sequencing, using a candidate gene approach, leads to a high prevalence of missed genetic diagnosis, classified as MODY-X. Next generation sequencing (NGS) panels provide a highly sensitive method even for rare forms. Methods: We investigated 28 pediatric subjects suspected for MODY-X, utilizing a 15-gene NGS panel for monogenic diabetes (MD). Results: NGS detected variants of uncertain significance (VUS), likely pathogenic or pathogenic for rarer subtypes of MODY, in six patients. We found variants in the wolframin gene (WFS1), traditionally not considered in MD genetic screening panels, in three patients; KCNJ11 gene mutation, typically responsible for neonatal diabetes and rarely causing isolated diabetes in adolescents; INS gene mutation; a variant in the HNF1B gene in a young male with diabetes on sulfonylurea treatment. Conclusion: In our cohort, the availability of an NGS panel for MD was determined for the correct identification of MD subtypes in six patients with MODY-X. Our study underlines how a precise diagnosis utilizing NGS may have an impact on the management of different forms of MODY and, thus, lead to a tailored treatment and enable genetic counselling of other family members.

Early-onset urological disorders due to Wolfram syndrome: A case of neonatal onset

Wolfram syndrome (WS) is an autosomal recessive neurodegenerative disorder characterized by DIDMOAD (diabetes insipidus, diabetes mellitus, optic atrophy, and deafness). Genetic analysis has demonstrated mutations of the WOLFRAMIN gene (WFS1) in patients with this syndrome (1), which may be complicated by other conditions, among them urological disorders (UDs). According to one study, UDs were found to occur in 19.39% (76/392) of WS patients with an average age of 20 yr (2), with only two patients presenting UDs before the age of 5 yr, both during infancy. We report here a neonatal case of WS presenting UDs.

Differential promoter activity by nucleotide substitution at a type 2 diabetes genome-wide association study signal upstream of the wolframin gene.

Functional knowledge of most genetic variants identified from genome-wide association studies (GWAS) for type 2 diabetes (T2D) is limited. A recent T2D GWAS revealed an association signal (rs4689388) upstream of the gene encoding Wolfram syndrome 1 (WFS1) whose intrinsic nucleotide variants had been previously associated with T2D in several candidate gene analyses. The aim of the present study was to identify functional variants of the GWAS signal. Promoter activity of luciferase reporter constructs was compared with haplotypes including variants composing a linkage disequilibrium block in the vicinity of rs4689388 in HEK293 and HepG2 cells. Promoter activity was highest with the most frequent haplotype (H1; ATCGT) and lowest with second most frequent haplotype (H2; GATCG), whose nucleotide alleles were all complementary to those of H1. Further analysis with artificial haplotypes revealed differential transcriptional activity by nucleotide substitution of rs4320200, rs13107806, or rs13127445 (P < 0.05). This concurred with changes in predicted transcription factor binding site by their allele substitutions. The previously reported GWAS signal for T2D may be identified by the differential promoter activity of rs4320200, rs13107806, and rs13127445 in the promoter of WFS1 by nucleotide substitution.

No association between wolframin gene H611R polymorphism and mood disorders: Evidence from 2570 subjects

Background: In the past few decades, a number of studies have investigated the association of the wolframin (WFS1) gene H611R polymorphism with mood disorders, but the findings are not always consistent. Aims: The objective of the present study is to assess the association between WFS1 gene H611R polymorphism and mood disorders by using a meta-analysis. Methods: A comprehensive literature search of PubMed, Excerpta Medica Database, Elsevier Science Direct and China National Knowledge Infrastructure databases was conducted to identify relevant articles, with the last report up to April 15, 2014. Pooled odds ratio (OR) with 95% confidence interval (CI) was estimated. Results: Seven studies including 1318 cases and 1252 controls were selected from potentially relevant articles. This meta-analysis showed that there was no significant association between WFS1 gene H611R polymorphism and mood disorders (R vs. H: OR = 0.93, 95% CI = 0.82–1.05, P = 0.22; HR+ RR vs. HH: OR = 0.98, 95% CI = 0.82–1.17, P = 0.80; RR vs. HH+ HR: OR = 0.84, 95% CI = 0.67–1.04, P = 0.11; RR vs. HH: OR = 0.86, 95% CI = 0.67–1.10, P = 0.24; HR vs. HH: OR = 1.03, 95% CI = 0.78–1.36, P = 0.83). In subgroup analyses by ethnicity, we did not detect any significant association of this polymorphism with mood disorders in Caucasian and Asian populations (P > 0.05). In subgroup analyses by types of mood disorders, we also did not detect any significant association of this polymorphism with bipolar disorder or major depressive disorder (P > 0.05). Conclusions: The results of this meta-analysis suggest that there is no association between WFS1 gene H611R polymorphism and mood disorders.

Energy Metabolism and Thyroid Function of Mice with Deleted Wolframin (Wfs1) Gene

There is no data about the energy metabolism of patients with Wolfram syndrome caused by mutations in the wolframin (Wfs1) gene. The aim of this study was to investigate the role of Wfs1 in energy metabolism and thyroid function in Wfs1 deficient mice (Wfs1KO). 16 male (8 Wfs1KO, 8 wild type (wt)) and 16 female (8 Wfs1KO, 8wt) mice aged 11-13 weeks were studied alone in a specific metabolic cage for 48 h. Body weight, food, water and O2 consumption, motor activity, CO2 and heat production of mice were recorded. At the age of 14-20 weeks, plasma levels of thyroxine (T4), TSH and leptin were measured and histology of thyroid tissues examined. Mean CO2 and heat production was not different between the groups. Mean O2 consumption was higher in the Wfs1KO females compared to the Wfs1KO males (3 410.0±127.0 vs. 2 806.0±82.4 ml/kg/h; p<0.05), but not compared to the wt mice. The mean movement activity was not different between the groups except that the Wfs1KO females reared up more often than the wt females (199.8±63.46 vs. 39.26±24.71 cnts/48 h; p<0.05). Both male and female Wfs1KO mice had significantly lower body mass and food intake than wt mice. Male Wfs1KO mice also lost more weight in metabolic cage than wt males (20.43±0.41 vs. 16.07±0.86%; p<0.05) indicating more pronounced response to isolation. Male Wfs1KO mice had significantly lower levels of plasma leptin than wt male mice (3.37±0.40 vs. 5.82±0.71 ng/ml; p<0.01). Thyroid function measured by serum TSH and T4 levels was not different between Wfs1KO and wt groups, but both Wfs1KO and wt male mice had significantly higher mean T4 levels than female mice. The histology of thyroid tissue of Wfs1KO males showed a trend to a smaller mean number of epithelial cells per follicle than the wt male mice.Although Wfs1KO mice were smaller and lost more weight during the experiment, their energy metabolism was not different from wt mice except that the female Wfs1KO mice consumed more O2. As mice in this study were relatively young, longitudinal studies in older mice are necessary to clarify whether Wfs1 has a role in energy metabolism when the disease progresses further.

WFS1‐deficient mice have alterations in energy metabolism: role of TRPM8 receptors (1126.17)

Wolfram syndrome, an autosomal recessive disorder characterized by juvenile‐onset diabetes mellitus and optic atrophy, is caused by mutations in the wolframin (Wfs1) gene. Wfs1 negatively regulates endoplasmic reticulum (ER) stress signalling and therefore have a role in the pathogenesis of diabetes and regulation of metabolism. One cardinal feature of Wfs1 mutant mice is their significantly reduced body weight. The real mechanism of weight loss is not known, but these mice develop normally until the age of 8 weeks. After this period weight loss starts. We recently found significant up‐regulation of TRPM8 gene in the hippocampus of Wfs1 mutant mice. TRPM8 is menthol receptor and is involved in the regulation of energy metabolism. In present study we analysed metabolic activity and sensitivity of Wfs1 mutant mice to the menthol stimulation. We found that Wfs1 mutant mice have elevated metabolic activity in metabolic cages. Moreover, menthol induced significant increase in basal metabolic activity in Wfs1 mutant mice. Over‐activation of TRPM8 receptor can explain increased metabolic rate in Wfs1 mutant mice and their reduced body weight.Grant Funding Source: Supported by The European Regional Development Fund

Association of aggression with a novel microRNA binding site polymorphism in the wolframin gene

Rare mutations in the WFS1 gene lead to Wolfram syndrome, a severe multisystem disorder with progressive neurodegeneration and diabetes mellitus causing life-threatening complications and premature death. Only a few association studies using small clinical samples tested the possible effects of common WFS1 gene variants on mood disorders and suicide, the non-clinical spectrum has not been studied yet. Self-report data on Aggression, Impulsiveness, Anxiety, and Depression were collected from a large (N = 801) non-psychiatric sample. Single nucleotide polymorphisms (SNPs) were selected to provide an adequate coverage of the entire WFS1 gene, as well as to include putative microRNA binding site polymorphisms. Molecular analysis of the assumed microRNA binding site variant was performed by an in vitro reporter-gene assay of the cloned 3' untranslated region with coexpression of miR-668. Among the 17 WFS1 SNPs, only the rs1046322, a putative microRNA (miR-668) binding site polymorphism showed significant association with psychological dimensions after correction for multiple testing: those with the homozygous form of the minor allele reported higher aggression on the Buss-Perry Aggression Questionnaire (P = 0.0005). Functional effect of the same SNP was also demonstrated in a luciferase reporter system: the minor A allele showed lower repression compared to the major G allele, if co-expressed with miR-668. To our knowledge, this is the first report describing a microRNA binding site polymorphism of the WFS1 gene and its association with human aggression based on a large, non-clinical sample.

WFS1 variants in Finnish patients with diabetes mellitus, sensorineural hearing impairment or optic atrophy, and in suicide victims

Mutations in the wolframin gene, WFS1, cause Wolfram syndrome, a rare recessive neurodegenerative disorder. The clinical features include early-onset bilateral optic atrophy (OA), diabetes mellitus (DM), diabetes insipidus, hearing impairment, urinary tract abnormalities and psychiatric illness, and, furthermore, WFS1 variants appear to be associated with non-syndromic DM and hearing impairment. Variation of WFS1 was investigated in Finnish subjects consisting 182 patients with DM, 117 patients with sensorineural hearing impairment (SNHI) and 44 patients with OA, and in 95 suicide victims. Twenty-two variants were found in the coding region of WFS1, including three novel nonsynonymous variants. The frequency of the p.[His456] allele was significantly higher in the patients with SNHI (11.5%; corrected P=0.00008), DM (6.6%; corrected P=0.036) or OA (9.1%; corrected P=0.043) than that in the 285 controls (3.3%). The frequency of the p.[His611] allele was 55.8% in the patients with DM being higher than that in the controls (47%; corrected P=0.039). The frequencies of p.[His456] and p.[His611] were similarly increased in an independent group of patients with DM (N=299). The results support previous findings that genetic variation of WFS1 contributes to the risk of DM and SNHI.

Valproic acid does not affect decreased insulin secretion in WFS1‐deficient pancreatic islets

Wolfram syndrome, an autosomal recessive disorder characterized by juvenile‐onset diabetes mellitus and optic atrophy, is caused by mutations in the wolframin (WFS1) gene. WFS1 negatively regulates endoplasmic reticulum (ER) stress signalling and therefore have a role in the pathogenesis of diabetes. Valproic acid (VPA), a widely used anticonvulsant and mood‐stabilizing drug, normalized the glucose intolerance in Wfs1 mutant mice, but had no effect on the course of glucose tolerance in wild‐type (WT) mice. The aim of this study was to investigate insulin secretion in isolated pancreatic islets of WFS1‐deficient (Wfs1KO) mice and also evaluate insulin secretion in the presence of VPA. In addition, the content of proinsulin in the isolated islets was measured. In general Wfs1KO pancreatic islets secreted less insulin compared to WT and Wfs1HZ islets. Differences in proinsulin amount were not statistically significant although there was a trend that Wfs1KO had an increased level of proinsulin. We found significantly reduced insulin secretion in Wfs1 mutants and no effect of VPA treatment.This study was supported by the Frontiers of Functional Genomics and by The European Regional Development Fund.

Atypical presentations of Wolframs syndrome

Background:Wolfram syndrome is a rare hereditary or sporadic neurodegenerative disorder also known as DIDMOAD. The classically described presentation is of insulin-dependent diabetes, followed by optic atrophy, central diabetes insipidus, and sensory neural deafness. Also included are less well-described presentations of Wolframs syndrome. We here present three cases of atypical presentation of this syndrome.Case 1:A 15-year-old boy with insulin-dependent diabetes was presented for evaluation of depressive symptoms associated with suicidal tendency. Neuropsychiatric manifestations are described with Wolframs syndrome, and wolframin gene, in recessive inheritance, is associated with psychiatric illnesses without other manifestations of Wolframs syndrome.Case 2:A 17-year-old diabetic boy on insulin with good control of blood sugar presented for evaluation of delayed puberty. Central hypogonadism and other anterior pituitary hormone dysfunctions are the less publicized hormone dysfunctions in Wolframs syndrome.Case 3:A 23-year-old female who was on insulin for diabetes for the past 14 years, got admitted for evaluation of sudden loss of vision. This patient had developed a vitreous hemorrhage and, on evaluation, was found to have optic atrophy, sensory neural hearing loss, and diabetes insipidus, and presented differently from the gradual loss of vision described in Wolframs syndrome.Conclusion:Wolframs syndrome being a multisystem degenerative disorder can have myriad other manifestations than the classically described features. Neuropsychiatric manifestations, depression with suicidal risk, central hypogonadism, and secondary adrenal insufficiency are among the less well-described manifestations of this syndrome.

Wolfram syndrome in the Polish population: novel mutations and genotype-phenotype correlation

Wolfram syndrome is a rare form of diabetes mellitus associated with optic atrophy and disorders of different organs (e.g. diabetes insipidus, hearing loss, ataxia, anaemia and many others). This syndrome is caused by recessive mutations in the wolframin gene (WFS1) localized on chromosome 4p16·1. The aim of this study was to identify the causative mutations in WFS1 in a group of Polish patients with suspected Wolfram syndrome. Nine patients with clinical symptoms consistent with Wolfram syndrome (at least diabetes mellitus and optic atrophy) and 22 first-degree relatives were examined. The molecular analysis was carried out by direct sequencing of the exons, the exon-intron junctions, and the 5' and 3' untranslated regions of WFS1. Nine different mutations in WFS1 (five of them novel) were identified in the nine patients. Six patients were homozygous for the following mutations: V412fs, S443R, W539X, V659fs. They developed diabetes at a mean age of 5·2 years. Three patients were compound-heterozygous for the following mutations: S167fs, Q392X, Y513fs, W648X, V779G. They developed diabetes at a mean age of 6·5 years. Mean age of diagnosis of diabetes among the Polish patients was typical for Wolfram syndrome; however, compound-heterozygous patients were slightly older at diabetes onset.

Rapidly progressive renal disease as part of Wolfram syndrome in a large inbred Turkish family due to a novel WFS1 mutation (p.Leu511Pro)

Wolfram syndrome, also named “DIDMOAD” (diabetes insipidus, diabetes mellitus, optic atrophy, and deafness), is an inherited association of juvenile-onset diabetes mellitus and optic atrophy as key diagnostic criteria. Renal tract abnormalities and neurodegenerative disorder may occur in the third and fourth decade. The wolframin gene, WFS1, associated with this syndrome, is located on chromosome 4p16.1. Many mutations have been described since the identification of WFS1 as the cause of Wolfram syndrome. We identified a new homozygous WFS1 mutation (c.1532T>C; p.Leu511Pro) causing Wolfram syndrome in a large inbred Turkish family. The patients showed early onset of IDDM, diabetes insipidus, optic atrophy, sensorineural hearing impairment and very rapid progression to renal failure before age 12 in three females. Ectopic expression of the wolframin mutant in HEK cells results in greatly reduced levels of protein expression compared to wild-type wolframin, strongly supporting that this mutation is disease-causing. The mutation showed perfect segregation with disease in the family, characterized by early and severe clinical manifestations.

Diabetes and Neurodegeneration in Wolfram Syndrome

OBJECTIVETo describe the diabetes phenotype in Wolfram syndrome compared with type 1 diabetes, to investigate the effect of glycemic control on the neurodegenerative process, and to assess the genotype-phenotype correlation.RESEARCH DESIGN AND METHODSThe clinical data of 50 patients with Wolfram syndrome-related diabetes (WSD) were reviewed and compared with the data of 24,164 patients with type 1 diabetes. Patients with a mean HbA1c during childhood and adolescence of ≤7.5 and >7.5% were compared with respect to the occurrence of additional Wolfram syndrome symptoms. The wolframin (WFS1) gene was screened for mutations in 39 patients. WFS1 genotypes were examined for correlation with age at onset of diabetes.RESULTSWSD was diagnosed earlier than type 1 diabetes (5.4 ± 3.8 vs. 7.9 ± 4.2 years; P < 0.001) with a lower prevalence of ketoacidosis (7 vs. 20%; P = 0.049). Mean duration of remission in WSD was 2.3 ± 2.4 vs. 1.6 ± 2.1 in type 1 diabetes (NS). Severe hypoglycemia occurred in 37 vs. 7.9% (P < 0.001). Neurologic disease progression was faster in the WSD group with a mean HbA1c >7.5% (P = 0.031). Thirteen novel WSF1 mutations were identified. Predicted functional consequence of WFS1 mutations correlated with age at WSD onset (P = 0.028).CONCLUSIONSEndoplasmic reticulum stress–mediated decline of β-cells in WSD occurs earlier in life than autoimmune-mediated β-cell destruction in type 1 diabetes. This study establishes a role for WFS1 in determining the age at onset of diabetes in Wolfram syndrome and identifies glucose toxicity as an accelerating feature in the progression of disease.

Sex Differences in the Development of Diabetes in Mice with Deleted Wolframin (Wfs1) Gene

Wolfram syndrome, caused by mutations in the wolframin (Wfs1) gene, is characterised by juvenile-onset diabetes mellitus, progressive optic atrophy, diabetes insipidus and deafness. Diabetes tend to start earlier in boys. This study investigated sex differences in longitudinal changes in blood glucose concentration (BGC) in wolframin-deficient mice (Wfs1KO) and compared their plasma proinsulin and insulin levels with those of wild-type (wt) mice. Non-fasting BGC was measured weekly in 42 (21 males) mice from both groups at nine weeks of age. An intraperitoneal glucose tolerance test (IPGTT) was conducted at the 30 (th) week and plasma insulin, c-peptide and proinsulin levels were measured at the 32 (nd) week. At the 32 (nd) week, Wfs1KO males had increased BGC compared to wt males (9.40±0.60 mmol/l vs. 7.91±0.20 mmol/l; p<0.05). The opposite tendency was seen in females. Both male and female Wfs1KO mice had impaired glucose tolerance on IPGTT. Wfs1KO males had significantly lower mean plasma insulin levels than wt males (57.78±1.80 ng/ml vs. 69.42±3.06 ng/ml; p<0.01) and Wfs1KO females (70.30±4.42 ng/ml; p<0.05). Wfs1KO males had a higher proinsulin/insulin ratio than wt males (0.09±0.02 vs. 0.05±0.01; p=0.05) and Wfs1KO females (0.04±0.01; p<0.05). Plasma c-peptide levels in males were lower in Wfs1KO males (mean 55.3±14.0 pg/ml vs. 112.7±21.9 pg/ml; p<0.05). Male Wfs1KO mice had a greater risk of developing diabetes than female Wfs1KO mice. Low plasma insulin concentration with an increased proinsulin/insulin ratio in Wfs1KO males indicates possible disturbances in converting proinsulin to insulin which in long-term may lead to insulin deficiency. Further investigation is needed to clarify the mechanism for the sex differences in the development of diabetes in Wolfram syndrome.

Male mice with deleted Wolframin (Wfs1) gene have reduced fertility

BackgroundWolfram Syndrome (WS) is an autosomal recessive disorder characterised by non-autoimmune diabetes mellitus, optic atrophy, cranial diabetes insipidus and sensorineural deafness. Some reports have described hypogonadism in male WS patients. The aim of our study was to find out whether Wfs1 deficient (Wfs1KO) male mice have reduced fertility and, if so, to examine possible causes.MethodsWfs1KO mice were generated by homologous recombination. Both Wfs1KO and wild type (wt) male mice were mated with wt female mice. The number of litters and the number of pups were counted and pregnancy rates calculated. The motility and morphology of the sperm and the histology of testes were analysed. Serum testosterone and FSH concentrations were also measured.ResultsThe pregnancy rate in wt females mated with Wfs1KO males was significantly lower than in the control group (15% vs. 32%; p < 0.05), but there was no significant difference in litter size. Analysis of male fertility showed that, in the Wfs1KO group, eight males out of 13 had pups whereas in the control group all 13 males had at least one litter. Sperm motility was not affected in Wfs1KO mice, but Wfs1KO males had less proximal bent tails (14.4 +/- 1.2% vs. 21.5 +/- 1.3 p < 0.05) and less abnormal sperm heads (22.8 +/- 1.8 vs. 31.5 +/- 3.5, p < 0.05) than wt males. Testes histology revealed significantly reduced number of spermatogonia (23.9 +/- 4.9 vs. 38.1 +/- 2.8; p < 0.05) and Sertoli cells (6.4 +/- 0.5 vs. 9.2 +/- 1.0; p < 0.05) in Wfs1KO mice. Serum testosterone and FSH concentrations did not differ between the two groups.ConclusionThe impaired fertility of Wfs1KO male mice is most likely due to changes in sperm morphology and reduced number of spermatogenic cells. The exact mechanism through which the Wfs1 gene influences sperm morphology needs to be clarified in further studies.

Wolframin gene H611R polymorphism: No direct association with suicidal behavior but possible link to mood disorders

Wolframin gene polymorphisms, including the H611R polymorphism, are reportedly associated with mood disorders and psychiatric hospitalization, but there is disagreement about the association of this specific variant with suicidality and impulsive traits. This study tested the association of the H611R polymorphism with mood disorders, suicidal behavior, and aggressive–impulsive traits. Two hundred and one subjects with mood disorders and 113 healthy volunteers were genotyped for the H611R polymorphism and underwent structured interviews for diagnosis and clinical ratings. All were Caucasians. The H611R polymorphism was associated with mood disorders but not suicidal behavior, aggressive/impulsive traits or suicidality in first-degree relatives. The HR heterozygote genotype was more frequent in mood disorder ( χ 2 = 7.505; df = 2; p = .023). If this finding will be replicated, the H611R polymorphism may be a possible marker for mood disorders in a psychiatric population, and not just in relatives of Wolfram syndrome probands.

WFS1 gene as a putative biomarker for development of post-traumatic syndrome in an animal model

Post-traumatic stress disorder (PTSD) is an anxiety disorder that may develop after the experiencing or witnessing of a life-threatening event. PTSD is defined by the coexistence of three clusters of symptoms: re-experiencing, avoidance and hyperarousal, which persist for at least 1 month in survivors of the event (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition). Using an established model of PTSD, we addressed the well-accepted clinical finding that only a minority (about 20%) of the individuals exposed to a traumatic event develop PTSD. Moreover, we followed individual rat behavior for up to a month, and then treated the PTSD-like animals with citalopram. Our data demonstrate high face (20% of rats exposed to a reminder of the stressor develop symptoms characteristic of PTSD) and predictive (response to citalopram) validities. Based on these validities we identified alterations in the Wolframin gene in the CA1 and amygdala regions, specifically in exposed PTSD-like rats, which were normalized after treatment with citalopram. We suggest the Wolframin gene as a putative biomarker for PTSD. Since Wolframin gene undergoes alternative splicing and has polymorphism in the population, it may serve a future marker for identification of the vulnerable population exposed to a traumatic event.

Expressional and functional studies of Wolframin, the gene function deficient in Wolfram syndrome, in mice and patient cells

Wolfram Syndrome is an autosomal recessive degenerative disorder of the neuroendocrine system. Diabetes mellitus is its lead symptom. Patients show mutations in the wolframin (WFS1) gene coding for a hydrophobic transmembrane protein of 890 amino acids. This protein was preliminarily localised in the endoplasmatic reticulum (ER) in cells of mice and rats. Mice lacking the WFS1 gene display degeneration of pancreatic β-cells following induction of ER stress. We here used antibodies against substructures of the wolframin protein in order to analyse its expression and localisation. Expression was detected in both pancreatic β-cells and the limbic system of mice. Using the rat insulinoma cell line RIN 5AH and fractionated mouse brain tissue, we confirmed wolframin localisation to the endoplasmic reticulum. Expression profiling on patient's primary fibroblasts revealed down-regulation of the diabetes associated plasma membrane glycoprotein (PC-1) gene, and up-regulation of fibulin-3, a gene connected to senescence. However, cell proliferation was indistinguishable from non-mutated cells. In contrast to data obtained on murine pancreatic islets, we found no increased apoptosis following induction of ER stress but rather by staurosporine treatment in the absence of WFS1 function. This indicates a new role of WFS1 deficiency in programmed cell death.

Wolframin mutations and hospitalization for psychiatric illness

Genetic predisposition plays an important role in most common psychiatric disorders. The identification of a specific gene associated with a psychiatric illness can lead to improved management of the gene-associated disorder. Mutations in the wolframin gene are associated with mental illness. Many patients with the Wolfram syndrome (WS), who are homozygous or compound heterozygous for wolframin mutations, have severe psychiatric symptoms. In WS families, close blood relatives, who have a high probability of carrying a single wolframin mutation, had a statistically significant excess, over spouse controls, of psychiatric hospitalizations, attempted and completed suicides, and self-reports of mental illness. Since heterozygous carriers of wolframin mutations are relatively frequent in the population according to the general Hardy-Weinberg principle, such mutations might be responsible for the illnesses of many psychiatric patients. The hypothesis that heterozygous carriers of a wolframin mutation are predisposed to psychiatric illness was tested in subjects from 25 WS families. In all, 11 relatives who had psychiatric hospitalizations could be genotyped through mutation analysis. Eight of these carried the wolframin mutation transmitted in their family, significantly (one-sided P=0.0022) more than the 3.0 expected if there were no association between psychiatric hospitalizations and mutations at this locus. All eight mutation-positive subjects had been hospitalized for a major depression. This confirmation of the association is not influenced by confounders, undetected stratification, or genetic heterogeneity. The relative risk of psychiatric hospitalization for depression was estimated to be 7.1 (95% CI 1.9-26.6) for carriers of a single wolframin mutation compared to noncarriers.