ISR inhibition reverses pancreatic β-cell failure in Wolfram syndrome models

Pancreatic β-cell failure by WFS1 deficiency is manifested in individuals with wolfram syndrome (WS). The lack of a suitable human model in WS has impeded progress in the development of new treatments. Here, human pluripotent stem cell derived pancreatic islets (SC-islets) harboring WFS1 deficiency and mouse model of β cell specific Wfs1 knockout were applied to model β-cell failure in WS. We charted a high-resolution roadmap with single-cell RNA-seq (scRNA-seq) to investigate pathogenesis for WS β-cell failure, revealing two distinct cellular fates along pseudotime trajectory: maturation and stress branches. WFS1 deficiency disrupted β-cell fate trajectory toward maturation and directed it towards stress trajectory, ultimately leading to β-cell failure. Notably, further investigation of the stress trajectory identified activated integrated stress response (ISR) as a crucial mechanism underlying WS β-cell failure, characterized by aberrant eIF2 signaling in WFS1-deficient SC-islets, along with elevated expression of genes in regulating stress granule formation. Significantly, we demonstrated that ISRIB, an ISR inhibitor, efficiently reversed β-cell failure in WFS1-deficient SC-islets. We further validated therapeutic efficacy in vivo with β-cell specific Wfs1 knockout mice. Altogether, our study provides novel insights into WS pathogenesis and offers a strategy targeting ISR to treat WS diabetes.

WFS1 Gene-associated Diabetes Phenotypes and Identification of a Founder Mutation in Southern India

CONTEXT

Wolfram syndrome (WFS) is a rare autosomal recessive disorder characterized by juvenile-onset diabetes, diabetes insipidus, optic atrophy, deafness, and progressive neurodegeneration. However, due to the progressive nature of the disease and a lack of complete clinical manifestations, a confirmed diagnosis of WFS at the time of onset of diabetes is a challenge.

OBJECTIVE

With WFS1 rare heterozygous variants reported in diabetes, there is a need for comprehensive genetic screening strategies for the early diagnosis of WFS and delineating the phenotypic spectrum associated with the WFS1 gene variants in young-onset diabetes.

METHODS

This case series of 11 patients who were positive for WFS1 variants were identified with next-generation sequencing (NGS)-based screening of 17 genemonogenic diabetes panel. These results were further confirmed with Sanger sequencing.

RESULTS

9 out of 11 patients were homozygous for pathogenic/likely pathogenic variants in the WFS1 gene. Interestingly, 3 of these probands were positive for the novel WFS1 (NM_006005.3): c.1107_1108insA (p.Ala370Serfs*173) variant, and haplotype analysis suggested a founder effect in 3 families from Southern India. Additionally, we identified 2 patients with young-onset diabetes who were heterozygous for a likely pathogenic variant or a variant of uncertain significance in the WFS1 gene.

CONCLUSION

These results project the need for NGS-based parallel multigene testing as a tool for early diagnosis of WFS and identify heterozygous WFS1 variants implicated in young-onset diabetes.

Loss of Function of WFS1 Causes ER Stress-Mediated Inflammation in Pancreatic Beta-Cells

Wolfram syndrome is a rare genetic disorder characterized by juvenile-onset diabetes mellitus, optic nerve atrophy, hearing loss, diabetes insipidus, and progressive neurodegeneration. Pathogenic variants in the WFS1 gene are the main causes of Wolfram syndrome. WFS1 encodes a transmembrane protein localized to the endoplasmic reticulum (ER) and regulates the unfolded protein response (UPR). Loss of function of WFS1 leads to dysregulation of insulin production and secretion, ER calcium depletion, and cytosolic calpains activation, resulting in activation of apoptotic cascades. Although the terminal UPR has been shown to induce inflammation that accelerates pancreatic β-cell dysfunction and death in diabetes, the contribution of pancreatic β-cell inflammation to the development of diabetes in Wolfram syndrome has not been fully understood. Here we show that WFS1-deficiency enhances the gene expression of pro-inflammatory cytokines and chemokines, leading to cytokine-induced ER-stress and cell death in pancreatic β-cells. PERK and IRE1α pathways mediate high glucose-induced inflammation in a β-cell model of Wolfram syndrome. M1-macrophage infiltration and hypervascularization are seen in the pancreatic islets of Wfs1 whole-body knockout mice, demonstrating that WFS1 regulates anti-inflammatory responses in pancreatic β-cells. Our results indicate that inflammation plays an essential role in the progression of β-cell death and diabetes in Wolfram syndrome. The pathways involved in ER stress-mediated inflammation provide potential therapeutic targets for the treatment of Wolfram syndrome.

Human iPSC-derived neurons reveal early developmental alteration of neurite outgrowth in the late-occurring neurodegenerative Wolfram syndrome

Recent studies indicate that neurodegenerative processes that appear during childhood and adolescence in individuals with Wolfram syndrome (WS) occur in addition to early brain development alteration, which is clinically silent. Underlying pathological mechanisms are still unknown. We have used induced pluripotent stem cell-derived neural cells from individuals affected by WS in order to reveal their phenotypic and molecular correlates. We have observed that a subpopulation of Wolfram neurons displayed aberrant neurite outgrowth associated with altered expression of axon guidance genes. Selective inhibition of the ATF6α arm of the unfolded protein response prevented the altered phenotype, although acute endoplasmic reticulum stress response-which is activated in late Wolfram degenerative processes-was not detected. Among the drugs currently tried in individuals with WS, valproic acid was the one that prevented the pathological phenotypes. These results suggest that early defects in axon guidance may contribute to the loss of neurons in individuals with WS.

Unique three-site compound heterozygous mutation in the WFS1 gene in Wolfram syndrome

BACKGROUND

Wolfram syndrome (WFS) is a rare autosomal recessive genetic disease whose main cause is mutations in the WFS1 and CISD2 genes. Its characteristic clinical manifestations are diabetes insipidus, diabetes mellitus, optic atrophy and deafness.

METHODS

In this study, two patients from this particular family underwent complete routine biochemical and ophthalmic tests. Blood, urine, routine stool test, visual acuity (VA) examination, visual field assessment, funduscope, optical coherence tomography and periorbital magnetic resonance imaging (MRI) scans were performed for each patient to evaluate whether the nerve fiber layer around the optic nerve head was atrophied and next-generation sequencing of target genes was performed in two patients.

RESULTS

When the patients were diagnosed with Wolfram syndrome, their genetic analyses suggested unique three-site compound heterozygous mutations (c.2314C > T + c.2194C > T + c.2171C > T) in exon 8 of both patients' chromosome 4. One mutation (c.2314C > T) was a novel mutation in the known reports of Wolfram syndrome. As a degenerative genetic disease, the types of gene mutations in the Chinese population are generally homozygous mutations at the unit point or compound heterozygous mutations at two nucleotide change sites. However, the two patients reported in this study are the first known cases of compound heterozygous mutations with three mutation sites coexisting on the WFS1 gene in China or even globally.

CONCLUSIONS

This study expands the phenotypic spectrum of Wolfram syndrome and may reveal a novel mutation pattern of pathogenesis of Wolfram syndrome. The implications of this discovery are valuable in the clinical diagnosis, prognosis, and treatment of patients with WFS1.

A novel mutation of WFS1 gene leading to increase ER stress and cell apoptosis is associated an autosomal dominant form of Wolfram syndrome type 1

BACKGROUND

Wolfram syndrome (WS) is a rare autosomal recessive disorder characterized by diabetes insipidus, diabetes mellitus, optic atrophy and deafness. Mutations in Wolfram syndrome 1 (WFS1) gene may cause dysregulated endoplasmic reticulum (ER)-stress and cell apoptosis, contributing to WS symptoms. The aim of this study was to identify the molecular etiology of a case of WS and to explore the functional consequence of the mutant WFS1 gene in vitro.

METHODS

A 27 years-old Chinese man was diagnosed as wolfram syndrome type 1 based on clinical data and laboratory data. DNA sequencing of WFS1 gene and mitochondrial m.3337G > A, m.3243A > G mutations were performed in the patient and his 4 family members. Functional analysis was performed to assessed the in vitro effect of the newly identified mutant. ER stress were evaluated by ER stress response element (ERSE)-luciferase assay. Cell apoptosis were performed by CCK-8, TUNEL staining and flow cytometric analysis.

RESULTS

A novel heterozygous 10-base deletion (c. 2067_2076 del10, p.W690fsX706) was identified in the patient. In vitro studies showed that mutant p.W690fsX706 increased ERSE reporter activity in the presence or absence of thapsigargin instead of wild type WFS1. Knockdown of WFS1 activated the unfolded protein response (UPR) pathway and increased the cell apoptosis, which could not be restored by transfection with WFS1 mutant (p.W690fsX706) comparable to the wild type WFS1.

CONCLUSIONS

A novel heterozygous mutation of WFS1 detected in the patient resulted in loss-of-function of wolframin, thereby inducing dysregulated ER stress signaling and cell apoptosis. These findings increase the spectrum of WFS1 gene mutations and broaden our insights into the roles of mutant WFS1 in the pathogenesis of WS.

Segregation of two variants suggests the presence of autosomal dominant and recessive forms of WFS1-related disease within the same family: expanding the phenotypic spectrum of Wolfram Syndrome

BACKGROUND

WFS1 was initially described as causative agent of autosomal recessive (AR) Wolfram syndrome, a childhood-onset disorder involving diabetes, optic atrophy, hearing loss and neurodegenerative features. However, the discovery of autosomal dominant (AD) disorders caused by this gene has resulted in clinical counselling and result interpretation challenges.

OBJECTIVE

We seek to report a family that appears to segregate dominant and recessive forms of WFS1-related disease.

METHODS/RESULTS

A 19-year-old woman presented with progressive childhood sensorineural hearing loss and recent optic atrophy, with biallelic mutations in WFS1: c.2486T>C (likely pathogenic) and c.2470G>A (uncertain significance). Her A1C was normal. Her sister carried the same variants and had a similar phenotype. Their father carried c.2486T>C and was found to have mild-moderate hearing loss but no optic atrophy or neurological symptoms. The mother carried c.2470G>A and had a normal audiogram and ophthalmological exam. Providing anticipatory guidance for this family was difficult given the phenotypic variability of WFS1-related disorders and the uncertainty surrounding whether the inheritance pattern was AR or AD.

CONCLUSION

The clinical correlation of the variants identified in this family suggests an AR Wolfram-like syndrome, without the typical diabetes mellitus or diabetes insipidus nor neurological decline. To our knowledge, this is a novel WFS1-related phenotype.

Adaptation of striated muscles to Wolframin deficiency in mice: Alterations in cellular bioenergetics

BACKGROUND

Wolfram syndrome (WS), caused by mutations in WFS1 gene, is a multi-targeting disease affecting multiple organ systems. Wolframin is localized in the membrane of the endoplasmic reticulum (ER), influencing Ca²⁺ metabolism and ER interaction with mitochondria, but the exact role of the protein remains unclear. In this study we aimed to characterize alterations in energy metabolism in the cardiac and in the oxidative and glycolytic skeletal muscles in Wfs1-deficiency.

METHODS

Alterations in the bioenergetic profiles in the cardiac and skeletal muscles of Wfs1-knock-out (KO) male mice and their wild type male littermates were determined using high resolution respirometry, quantitative RT-PCR, NMR spectroscopy, and immunofluorescence confocal microscopy.

RESULTS

Oxygen consumption without ATP synthase activation (leak) was significantly higher in the glycolytic muscles of Wfs1 KO mice compared to wild types. ADP-stimulated respiration with glutamate and malate was reduced in the Wfs1-deficient cardiac as well as oxidative and glycolytic skeletal muscles.

CONCLUSIONS

Wfs1-deficiency in both cardiac and skeletal muscles results in functional alterations of energy transport from mitochondria to ATP-ases. There was a substrate-dependent decrease in the maximal Complex I -linked respiratory capacity of the electron transport system in muscles of Wfs1 KO mice. Moreover, in cardiac and gastrocnemius white muscles a decrease in the function of one pathway were balanced by the increase in the activity of the parallel pathway.

GENERAL SIGNIFICANCE

This work provides new insights to the muscle involvement at early stages of metabolic syndrome like WS as well as developing glucose intolerance.

Retinal thickness as a marker of disease progression in longitudinal observation of patients with Wolfram syndrome

AIMS

Wolfram syndrome (WFS) is a recessively inherited monogenic form of diabetes coexisting with optic atrophy and neurodegenerative disorders with no currently recognized markers of disease progression. The aim of the study was to evaluate retinal parameters by using optical coherence tomography (OCT) in WFS patients after 2 years of follow-up and analysis of the parameters in relation to visual acuity.

METHODS

OCT parameters and visual acuity were measured in 12 WFS patients and 31 individuals with type 1 diabetes.

RESULTS

Total thickness of the retinal nerve fiber layer (RNFL), average retinal thickness and total retinal volume decreased in comparison with previous OCT examination. Significant decreases were noted for RNFL (average difference -17.92 µm 95% CI -30.74 to -0.10; p = 0.0157), macular average thickness (average difference -5.38 µm 95% CI -10.63 to -2.36; p = 0.0067) and total retinal volume (average difference -0.15 mm³ 95% CI -0.30 to -0.07; p = 0.0070). Central thickness remained unchanged (average difference 1.5 µm 95% CI -7.61 to 10.61; p = 0.71). Visual acuity of WFS patients showed a strong negative correlation with diabetes duration (R = -0.82; p = 0.0010). After division of WFS patients into two groups (with low-vision and blind patients), all OCT parameters except for the RNFL value were lower in blind WFS patients.

CONCLUSIONS

OCT measures structural parameters and can precede visual acuity loss. The OCT study in WFS patients should be performed longitudinally, and serial retinal examinations may be helpful as a potential end point for future clinical trials.

A novel nonsense mutation in the WFS1 gene causes the Wolfram syndrome

Wolfram syndrome is a rare autosomal recessive neurodegenerative disorder, which is mostly caused by mutations in the WFS1 gene. The WFS1 gene product, which is called wolframin, is thought to regulate the function of endoplasmic reticulum. The endoplasmic reticulum has a critical role in protein folding and material transportation within the cell or to the surface of the cell. Identification of new mutations in WFS1 gene will unravel the molecular pathology of WS. The aim of this case report study is to describe a novel mutation in exon 4 of the WFS1 gene (c.330C>A) in a 9-year-old boy with WS.

Three cases of Wolfram syndrome with different clinical aspects

BACKGROUND

Wolfram syndrome is an autosomal recessive disorder caused by mutations in the WFS1 gene. Clinical heterogeneity has been reported both within and between families with WFS1 mutations.

SUBJECTS

The first case was diagnosed with insulin-dependent diabetes mellitus with positive for pancreatic autoantibodies and had a ketoacidotic attack in the follow-up period. The second case presented initially with optic atrophy and was diagnosed with behavioral and psychiatric problems at an early age. The third case had early onset insulin-dependent diabetes with multiple anomalies and congenital hypothyroidism. Many of these features have not been reported previously in patients with Wolfram syndrome. In all three patients homozygous mutations in WFS1 were identified.

CONCLUSION

Wolfram syndrome is a disease where the characteristic features may present at different times. A diagnosis of Wolfram syndrome should therefore be considered even in the absence of the full spectrum of clinical features.

Significant expressivity of Wolfram syndrome: phenotypic assessment of two known and one novel mutation in the WFS1 gene in three Iranian families

Wolfram syndrome also known as DIDMOAD (Diabetes Insipidus, Diabetes Mellitus, Optic Atrophy, and Deafness) is a rare neurodegenerative autosomal recessive disorder. There is evidence of variable expressivity both in patients and heterozygous carriers. In this study, we describe three Persian Wolfram syndrome families with differences in the age of onset, signs and symptoms of the disease. We clinically evaluated affected families for verifying WS clinical diagnosis. After linkage analysis via 5 STR markers, molecular analysis for WFS1 was performed by direct sequencing for patients and available family members. Three homozygous mutations were identified including c.1885 C>T, c.2205C>A both in exon 8 and c.460+1G>A in intron 4. The mutation c.2205C>A was found to be novel. We report interesting phenotype-genotype correlations: homozygous c.1885C>T and c.2205C>A variants were correlated with quite different disease severity and onset in the siblings. We report a rare case of WS with homozygous c.1885C>T who is married and has a healthy child. c.460+1G>A showed a possible partial dominant inheritance put forth by a heterozygous parent showing partial WS symptoms while her daughter displayed typical WS symptoms. Due to variable expressivity, detailed clinical examination and molecular diagnostics should be used to confirm WS and a more exact recurrence risk data.

β-cell dysfunction due to increased ER stress in a stem cell model of Wolfram syndrome

Wolfram syndrome is an autosomal recessive disorder caused by mutations in WFS1 and is characterized by insulin-dependent diabetes mellitus, optic atrophy, and deafness. To investigate the cause of β-cell failure, we used induced pluripotent stem cells to create insulin-producing cells from individuals with Wolfram syndrome. WFS1-deficient β-cells showed increased levels of endoplasmic reticulum (ER) stress molecules and decreased insulin content. Upon exposure to experimental ER stress, Wolfram β-cells showed impaired insulin processing and failed to increase insulin secretion in response to glucose and other secretagogues. Importantly, 4-phenyl butyric acid, a chemical protein folding and trafficking chaperone, restored normal insulin synthesis and the ability to upregulate insulin secretion. These studies show that ER stress plays a central role in β-cell failure in Wolfram syndrome and indicate that chemical chaperones might have therapeutic relevance under conditions of ER stress in Wolfram syndrome and other forms of diabetes.

Diabetes: Targeting endoplasmic reticulum to combat juvenile diabetes

Limited options for clinical management of patients with juvenile-onset diabetes mellitus call for a novel therapeutic paradigm. Two innovative studies support endoplasmic reticulum as an emerging target for combating both autoimmune and heritable forms of this disease.

[Wolfram syndrome: from definition to molecular bases]

Wolfram syndrome (WS) is an autosomal recessive progressive neurodegenerative disorder characterized by diabetes mellitus and optic atrophy. Diabetes insipidus and sensorineural deafness are also noted frequently, explaining the acronym DIDMOAD (diabetes insipidus, diabetes mellitus, optic atrophy and deafness) by which the syndrome is also referred. Additional manifestations such as atonic bladder, ataxia, nystagmus and predisposition for psychiatric illness may be present. The Wolfram syndrome gene, WFS1, was mapped to chromosome 4p16.1 by positional cloning. It encodes an 890-amino-acid polypeptide named wolframin. Although the wolframin function is still not completely known, its localization to the endoplasmic reticulum suggests it can play a role in calcium homeostasis, membrane trafficking and protein processing. Knowing the cellular function of wolframin is necessary for understanding the pathophysiology of Wolfram syndrome. This knowledge may lead to development of therapies to prevent or reduce the outcomes of WS.

Identification of novel mutations in WFS1 and genotype-phenotype correlation in Wolfram syndrome

Mutations in the WFS1 gene have been reported in Wolfram syndrome (WS), an autosomal recessive disorder defined by early onset of diabetes mellitus (DM) and progressive optic atrophy. Because of the low prevalence of this syndrome and the recent identification of the WFS1 gene, few data are available concerning the relationships between clinical and molecular aspects of the disease. Here, we describe 12 patients from 11 families with WS. We report on eight novel (A214fsX285, L293fsX303, P346L, I427S, V503fsX517, R558C, S605fsX711, P838L) and seven previously reported mutations. We also looked for genotype-phenotype correlation both in patients included in this study and 19 additional WS patients that were previously reported. Subsequently, we performed a systematic review and meta-analysis of five published clinical and molecular studies of WFS1 for genotype-phenotype correlation, combined with our current French patient group for a total of 96 patients. The presence of two inactivating mutations was shown to predispose to an earlier age of onset of both DM and optic atrophy. Moreover, the clinical expression of WS was more complete and occurred earlier in patients harboring no missense mutation.

Pigmentary maculopathy in a patient with Wolfram syndrome

CASE REPORT

We describe a rare association of pigmentary maculopathy with Wolfram syndrome not previously reported in the literature. A 12-year-old boy presented to the retina service with a diagnosis of Wolfram syndrome and a history of poor central vision. The patient was found to have bilateral atrophic pigmentary maculopathy that was confirmed with fluorescein angiography.

COMMENTS

Wolfram syndrome may present with a pigmentary maculopathy and this rare finding may assist the clinician in making appropriate genetic referral when this diagnosis is suspected.

Wolfram syndrome

Wolfram syndrome (WFS) is a rare diffuse neurodegenerative disorder characterized by diabetes insipidus, diabetes mellitus, optic atrophy, deafness, and a wide variety of central nervous system abnormalities. Insulin-dependent diabetes mellitus with optic nerve atrophy is sufficient criteria for the diagnosis. WFS is a devastating disease for the patients and their families. This study emphasizes the need for careful evaluation of cases having insulin-dependent diabetes mellitus and optic atrophy.

Wolfram syndrome presenting marked brain MR imaging abnormalities with few neurologic abnormalities

Wolfram syndrome is a rare autosomal recessive disorder featuring diabetes insipidus, diabetes mellitus, optic atrophy, and deafness; DIDMOAD is a commonly accepted anonym for this disorder. We describe a 35-year-old man with Wolfram syndrome, who had marked atrophy of the brain stem, middle cerebellar peduncle, and cerebellum. Despite these MR imaging findings involving the pontocerebellar tract, the patient had no neurologic abnormalities suggesting dysfunction of the brain stem or cerebellum. Patients with Wolfram syndrome may have discrepancies between neurologic and radiologic findings.

Clinical picture, evolution and peculiar molecular findings in a very large pedigree with Wolfram syndrome

OBJECTIVES

a) To describe a very extended inbred pedigree with Wolfram syndrome (WS) (OMIM #222300); b) to report both the clinical picture and evolution in this large family and a peculiar mutation which has been reported hitherto only in Italian patients.

DESIGN

The five-generation pedigree from Sicily was reconstructed through a proband with all the main manifestation of WS, born to a couple of healthy consanguineous parents. DNA examination was performed in both patients and healthy family members.

RESULTS

In all seven patients we found a homozygous 16-bp deletion in exon 8 of the WFS1 gene that introduces a stop codon in position 454.

CONCLUSIONS

This inbred pedigree is the largest with WS described in the literature. Its analysis definitively confirms the view of autosomal recessive inheritance in WS. The 16-bp deletion appears to be a relatively frequent mutation only in Italian patients. Before examining the entire coding region of the WSF1 gene a preliminary screening for the 16-bp deletion in exon 8 might be suggested when a new Italian case of WS is investigated.

Diabète et cytopathies mitochondriales : données anatomo-pathologiques

Maternal diabetes associated with neural deafness is designated as MIDD (maternal inherited diabetes and deafness); it is linked to a A3243G tRNA leucine gene mutation. The disease course is progressive and involvement of other systems is frequent. In most cases, macular pattern dystrophy is present. Muscular lesions are characteristic of mitochondrial myopathies. Mitochondrial abnormalities have also been observed in pancreas, heart, kidney, smooth muscle of the digestive tract with variable heteroplasmy levels. MIDD may present as a single syndrome or is part of MELAS or Kearns-Sayre syndrome.

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 beta-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 beta-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.

Cranial magnetic resonance imaging of Wolfram (DIDMOAD) syndrome

Wolfram syndrome is a rare neurodegenerative disorder characterized by diabetes insipidus, diabetes mellitus, optic atrophy and deafness (DIDMOAD). A wide spectrum of abnormalities of the central nervous system, urinary tract and endocrine glands is also observed. We report cranial MRI findings in a 32-year-old female patient with Wolfram syndrome. In addition to the classical features, including absence of the normal high signal of the neurohypophysis, atrophy of visual pathways, the brainstem, cerebellum and cerebral cortex, we observed bilateral hyperintensity on proton density- and T2- weighted images related to the optic radiations in the periventricular white matter of the temporal and parieto-occipital lobes, which may reflect gliosis pathologically.

Imaging characteristics of familial Wolfram syndrome

Wolfram syndrome is a rare diffuse neurodegenerative disorder also known as DIDMOAD due to its characteristics of diabetes insipidus, diabetes mellitus, optic nerve atrophy and deafness. It is also associated with a wide variety of abnormalities of the central nervous system, urinary tract and endocrine glands. It may be familial or sporadic. Imaging findings include absence of the short T1 nature of the pituitary posterior lobe, atrophy of the optic nerve, chiasma, and tracts. Atrophy of the brain stem and cerebellum has also been reported. We describe a 15-year-old boy and an 11-year-old girl with Wolfram syndrome who were siblings from a diabetes mellitus family. They received regular insulin control at our hospital and had symptoms of frequent urinary tract infection and diabetes insipidus. Magnetic resonance imaging revealed marked pons and cerebellar atrophy. Optic nerve and chiasma atrophy was also noted.

Disruption of the WFS1 gene in mice causes progressive -cell loss and impaired stimulus-secretion coupling in insulin secretion

Wolfram syndrome, an autosomal recessive disorder characterized by juvenile-onset diabetes mellitus and optic atrophy, is caused by mutations in the WFS1 gene. In order to gain insight into the pathophysiology of this disease, we disrupted the wfs1 gene in mice. The mutant mice developed glucose intolerance or overt diabetes due to insufficient insulin secretion in vivo. Islets isolated from mutant mice exhibited a decrease in insulin secretion in response to glucose. The defective insulin secretion was accompanied by reduced cellular calcium responses to the secretagogue. Immunohistochemical analyses with morphometry and measurement of whole-pancreas insulin content demonstrated progressive beta-cell loss in mutant mice, while the alpha-cell, which barely expresses WFS1 protein, was preserved. Furthermore, isolated islets from mutant mice exhibited increased apoptosis, as assessed by DNA fragment formation, at high concentration of glucose or with exposure to endoplasmic reticulum-stress inducers. These results strongly suggest that WFS1 protein plays an important role in both stimulus-secretion coupling for insulin exocytosis and maintenance of beta-cell mass, deterioration of which leads to impaired glucose homeostasis. These WFS1 mutant mice provide a valuable tool for understanding better the pathophysiology of Wolfram syndrome as well as WFS1 function.

Wolfram syndrome: identification of a phenotypic and genotypic variant from Jordan

Wolfram syndrome is an autosomal recessive disorder with probable locus heterogeneity. Only insulin-dependent diabetes mellitus and progressive optic-nerve atrophy are necessary to make the diagnosis, but associated findings include diabetes insipidus, sensorineural hearing loss, ataxia, peripheral neuropathy, urinary-tract atony, and psychiatric illnesses. We performed clinical and molecular studies on four consanguineous families with 16 affected individuals. We point out a new phenotypic variant with absent diabetes insipidus, presence of peptic ulcer disease and bleeding tendency secondary to a platelet aggregation defect. The same phenotypic variant turned out to be a genotypic variant with linkage to a second Wolfram syndrome locus (WFS2) on chromosome 4q22-24.

Non-syndromic progressive hearing loss DFNA38 is caused by heterozygous missense mutation in the Wolfram syndrome gene WFS1

Dominantly inherited progressive hearing loss DFNA38 is caused by heterozygosity for a novel mutation in WFS1, the gene for recessively inherited Wolfram syndrome. Wolfram syndrome is defined by juvenile diabetes mellitus and optic atrophy and may include progressive hearing loss and other neurological symptoms. Heterozygotes for other Wolfram syndrome mutations generally have normal hearing. Dominant deafness defined by DFNA38 is more severe than deafness of Wolfram syndrome patients and lacks any syndromic features. In a six-generation kindred from Newfoundland, Canada, WFS1 Ala716Thr (2146 G-->A) was shared by all deaf members of the family and was specific to deaf individuals. The causal relationship between this missense mutation and deafness was supported by two observations based on haplotype and mutation analysis of the kindred. First, a relative homozygous for the mutation was diagnosed at age 3 years with insulin-dependent diabetes mellitus, the central feature of Wolfram syndrome. Second, two relatives with normal hearing had an identical haplotype to that defining DFNA38, with the exception of the base pair at position 2146. Other rare variants of WFS1 co-inherited with deafness in the family could be excluded as disease-causing mutations on the basis of this hearing-associated haplotype. The possibility that 'mild' mutations in WFS1 might be a cause of non-syndromic deafness in the general population should be explored.

Evidence of widespread axonal pathology in Wolfram syndrome

Wolfram syndrome, characterised by diabetes insipidus, diabetes mellitus, optic atrophy sensorineural deafness and acquired urinary tract abnormalities, is an hereditary neurodegenerative syndrome, the pathogenesis of which is unknown. We report the post-mortem findings on a patient with well-documented Wolfram syndrome. The brain showed severe degeneration of the optic nerves, chiasm and tracts as well as severe loss of neurons from the lateral geniculate nuclei, basis pontis, and the hypothalamic paraventricular and supraoptic nuclei. In addition, there was a widespread axonal dystrophy with axonal swellings in the pontocerebellar tracts, the optic radiations, the hippocampal fornices and the deep cerebral white matter. This widespread axonal pathology parallels the pattern of neurodegeneration and in many areas is more striking than neuronal loss.

Optic atrophy in Wolfram (DIDMOAD) syndrome

Wolfram syndrome is the association of diabetes mellitus and optic atrophy, also called DIDMOAD (diabetes insipidus, diabetes mellitus, optic atrophy and deafness). Incomplete characterisation has caused diagnostic confusion; we therefore undertook a nation-wide cross-sectional case finding study. We identified 45 patients with Wolfram syndrome, median age 29 years. All patients fulfilled the ascertainment criteria (juvenile onset diabetes mellitus and optic atrophy). Optic atrophy presented in 38 patients with reduced visual acuity and colour vision defect (median age 11 years), progressing to visual acuity of 6/60 or less in 35 patients (median time 8 years, range 1-25 years). Visual field examinations recorded before acuity deteriorated showed central scotomas with peripheral constriction. Blind patients had absent pupillary reflexes. Horizontal nystagmus was seen in patients with other signs of cerebellar degeneration. There was no pigmentary retinal dystrophy; only 3 patients had background diabetic retinopathy, despite a median duration of diabetes of 24 years. Electroretinography was normal in 3 patients and showed reduced amplitude in 3 patients; visual evoked responses were abnormal (10/10 patients: reduced amplitude to both flash and pattern stimulation). Magnetic resonance imaging showed generalised brain atrophy with reduced signal from the optic nerves and chiasm. A postmortem brain specimen from one patient revealed atrophy of the optic nerves, chiasm, cerebellum and brainstem. We found no evidence of mitochondrial genome defects or rearrangements. This primary neurogenerative disorder presents with diabetes mellitus and progressive optic atrophy, probably due to pathology in the optic nerve.

Wolfram syndrome: a neuropathological study

Neuropathological examination was carried out on a patient aged 37 years who had suffered from Wolfram syndrome. Atrophy of the olfactory bulbs and tracts, atrophy of the optic nerves and chiasm, loss of neurons in the lateral geniculate nuclei mainly affecting the small cell layers, atrophy of the superior colliculus, loss of fibers in the cochlear nerve and mild loss of neurons in the cochlear nuclei and inferior colliculus, mild olivopontocerebellar atrophy, and demyelination of the pyramidal tracts were the main neuropathological findings. These correlated with anosmia, loss of vision, loss of hearing, cerebellar symptoms and signs, Babinski sign, and clonus, respectively, clinically observed in this patient. Mild neuron loss and gliosis in the preoptic and paraventricular area of the hypothalamus and mild motor neuron loss in the spinal cord did not reach thresholds of impaired function, although loss of neurons in discrete bulbar nuclei might have accounted for the late episode of food aspiration and suffocation. The relationship between memory loss, personality disturbances, and signs of prefrontal release and mild loss of neurons in the anterior and dorso-medial nuclei of the thalamus remains unclear.

Various clinical aspects of DIDMOAD (Wolfram) syndrome

The association of juvenile diabetes mellitus (DM), diabetes insipidus (DI), optic atrophy (OA) and sensorineural deafness (D) is known as DIDMOAD or Wolfram syndrome. Aside from these four cardinal features, a wide variety of abnormalities of the nervous system, urinary tract and endocrine glands have been described in this syndrome. In this report, the clinical features of six patients with DIDMOAD syndrome are presented. All six patients had DM. Five of the six patients had DI, five OA and five displayed abnormal audiogram findings. In addition, two had goiter, two delayed puberty, one seizure and one mental retardation with depression attacks. Urinary tract dilatation was recorded in five patients. Four patients developed typical complications of DM. One of them had overt nephropathy and arthropathy despite the short duration of DM. In addition, this patient had diabetic retinopathy, which is considered to be rare in this syndrome.

Biochemical and molecular studies of mitochondrial function in diabetes insipidus, diabetes mellitus, optic atrophy, and deafness

OBJECTIVE

To determine if diabetes insipidus, diabetes mellitus, optic atrophy, and deafness (DIDMOAD) combined with a cerebellar syndrome is associated with a systemic disorder of respiratory chain function as found in similar genetic syndromes.

CASE

A muscle biopsy was taken from a patient with DIDMOAD, and a mitochondrial fraction was prepared. Respiratory chain function was assessed by analysis of intermediary metabolites, histochemical analysis of muscle biopsy, measurement of the activity of individual respiratory chain complexes, oxidative flux through the respiratory chain, and cytochrome concentration and compared with a population with normal respiratory chain function. Mitochondrial DNA from skeletal muscle, brain, and pancreas was examined for major rearrangements and specific point mutations. Brain tissue was examined neuropathologically for abnormalities, particularly those previously described in association with DIDMOAD.

RESULTS

No abnormality was found in mitochondrial oxidation, individual complex activity, or cytochrome concentration. Histochemical analysis and electron microscopy showed no abnormality known to be associated with mitochondrial dysfunction. A single-base substitution at position 12308 of the mitochondrial genome was found, but no major rearrangement of mitochondrial DNA was demonstrated. Neuropathological examination revealed severe demyelination and gliosis in the optic nerves and loss of Purkinje cells associated with gliosis in the white matter in the cerebellum.

CONCLUSIONS

We have found no evidence that DIDMOAD is associated with a systemic abnormality of respiratory chain function. The mitochondrial DNA single-base substitution noted is likely to be a polymorphism rather than a pathogenic point mutation. We have confirmed that DIDMOAD may be associated with a neurodegenerative disorder, but the cause of this remains undetermined.

Wolfram syndrome. A report of four cases and review of the literature

This is a report of four new cases of Wolfram syndrome in three families and a review of the literature. The ophthalmologic, urologic, otologic, psychiatric and endocrine findings of the syndrome are discussed as well as their pathophysiology. Two recent reports with features atypical of the Wolfram syndrome are discussed. The genetics of this syndrome are also discussed.

[Optic neuropathy in diabetic subjects]

Four clinical forms of optic neuropathy can occur in diabetes: 1. Axial neuropathy is a classical optic neuropathy. 2. Anterior ischemic optic neuropathy is an acute optic disc ischaemia and the visual loss depends on the number of fibers destroyed. 3. Acute disc swelling occurs in young patients with a type 1 diabetes. It can be asymptomatic, but can also simulate optic disc new-vessels. It seems not to be a ciliary but rather an epipapillary and peripapillary capillaropathy. 4. Optic atrophy can constitute the final out come of forms one and too. In the child, the Wolfram ou DIDMOAD syndrome associates diabetes insipidus, diabetes mellitus, optic atrophy and deafness.

The Wolfram syndrome: a primary neurodegenerative disorder with lethal potential

We describe four cases of the Wolfram syndrome; a rare congenital syndrome characterised in it's complete form by diabetes mellitus, diabetes insipidus, optic atrophy, nerve deafness and dilatation of the urinary tract. All four of the cases described developed grand mal epilepsy in their second and third decades. Two of the cases developed progressive ataxia. There was one death due to status epilepticus. Absence of most of the corpus callosum and of the septum pellucidum was noted at autopsy. This pathological finding has not been reported previously in this syndrome. These cases highlight the neuro-degenerative aspects of the Wolfram syndrome. The literature on neurological aspects of the syndrome is reviewed.

[Diabetes mellitus, diabetes insipidus, optic atrophy and deafness]

In France, the combination of diabetes insipidus, diabetes mellitus, optic atrophy, and deafness (DIDMOAD) is designated as Wolfram syndrome. An analysis of 14 personal cases and previous reports showed that the syndrome develops gradually and specified the most common order of occurrence of the various components as well as the other abnormalities (e.g., of the urinary tract) which may be found. Wolfram syndrome is an inherited condition (recessive autosomal transmission). The lack of association with HLA antigens seems to have been established (in the few cases where HLA typing was performed). The prognosis of Wolfram syndrome is grim, with the occurrence of each additional component adding to the severity of the disease.

[A long-term follow-up of a patient with DIDMOAD (Wolfram) syndrome]

A 19-year-old Japanese woman developed diabetes mellitus, diabetes insipidus and optic atrophy. Other abnormal ocular findings included color blindness, elevated dark adaptation threshold and constriction of visual fields. Diabetic retinopathy, which is considered to be rare in this syndrome, also was found in the fundi of this patient. During the nine-year follow-up period, diabetic retinopathy deteriorated despite treatment by photocoagulation and vitrectomy, suggesting the importance of ophthalmological examinations in patients with DIDMOAD syndrome.

A Chinese family with Wolfram syndrome presenting with rapidly progressing diabetic retinopathy and renal failure

We describe a Chinese family with three siblings, all females, presenting with the Wolfram Syndrome. All three cases had almost similar clinical presentation of insulin-dependent diabetes mellitus, with rapid development of severe renal and retinal complications. Two siblings died at age thirty and thirty-one years of end-stage renal failure. All three cases had visual symptoms since early childhood progressing rapidly to loss of vision. Two of the three siblings had severe diabetic retinopathy requiring laser photocoagulation. These presentations are in contrast to most reported cases of the Wolfram syndrome where advanced diabetic eye complication is a rare feature. We also present several features present in one of the siblings, viz., microcephaly, microstomia, clinodactylyl, brachydactylyl, empty sella syndrome and severe hypoplasia of the right internal carotid vessels associated with mild narrowing of the left internal carotid artery which have not been previously described.

[Description of Wolfram syndrome (DIDMOAD) on the basis of a new case]

We present a new clinical case of a 25-year-old man with Wolfram's syndrome. Partial central diabetes insipidus was found to cause polyuria, polydipsia and enuresis. The patient had diabetes mellitus for the last 18 years, controlled with diet and/or chlorpropamide during 10 years and showed no typical complications of the disease. The patient was also shown to have a dilated urinary tract and perceptive hypoacusis for high frequencies. The fifth classical component of this syndrome, primary optic atrophy, was not found. Based on the report of this case, Wolfram's syndrome is briefly described.

Genetically programmed selective islet beta-cell loss in diabetic subjects with Wolfram's syndrome

Insulin-producing beta-cells were selectively absent from the islets of Langerhans in postmortem specimens from two patients with Wolfram's syndrome. In families with multiple cases of this syndrome, we found a very high concordance rate (r = .910, P less than .001) among siblings for age at onset of diabetes mellitus. Taken together with the lack of markers for an autoimmune process, these findings suggest that diabetes mellitus in this syndrome results from genetically programmed selective beta-cell death.

Optic atrophy in Wolfram syndrome

The clinical and electrophysiologic findings in 11 cases of Wolfram syndrome are presented. These findings suggest that optic atrophy in Wolfram syndrome is not secondary to retinal pathology, but probably represents part of a generalized degeneration of neural structures. The relationship of diabetes mellitus to this process of neural degeneration remains unclear.