Mutation analysis of the WFS1 gene in seven Danish Wolfram syndrome families; four new mutations identified

There's More Than Meets the Eye: Wolfram Syndrome in a Type I Diabetic Patient

Wolfram syndrome (WS) is a rare neurodegenerative and genetic disorder, also known by the synonym DIDMOAD, which stands for diabetes insipidus (DI), childhood-onset diabetes mellitus (DM), optic atrophy (OA), and deafness (D). We present a case of a 25-year-old diabetic patient, using insulin for 15 years, who had increasing polyuria and polydipsia, along with progressive hearing and vision loss. Laboratory tests revealed elevated hemoglobin A1c (HbA1c) and blood sugar levels. Optic nerve, optic chiasm, pons, and brain stem atrophy was seen on magnetic resonance imaging (MRI) of brain. After workup, a diagnosis of DI was made. Once the diagnosis was reached, treatment with subcutaneous insulin and nasal desmopressin improved patient's symptoms. In juvenile diabetic patients presenting with new onset or worsening polyuria and polydipsia, the possibility of WS should be considered. Early diagnosis and initiation of appropriate management leads to improved outcomes and the quality of life.

Neurosensory Affectation in Patients Affected by Wolfram Syndrome: Descriptive and Longitudinal Analysis

Wolfram syndrome (WS) is a rare neurodegenerative disease usually of autosomal recessive origin. There is limited research about sensorineural hearing loss, despite it being a fundamental entity. It is important to broaden the study of this disease and specify a set of tests required for an adequate assessment of patients for efficient monitoring and control. The fundamental objective of this research is to understand WS from a biomedical perspective in order to help in its diagnosis, follow-up, and control. Pure tones audiometry, tympanometry, speech perception, the speech intelligibility index without aid, and testing at high frequencies were among the audiological measurements utilised since they were deemed suitable for standardised follow-up. Mixed linear models were used to examine the effects of age, time, or mean interaction in pure-tone (IPT), the average of high frequencies (HFA), auditory brainstem response (ABR), and brainstem auditory evoked potentials (BAEP). The genetic analysis allowed mutations to be classified into three phenotype-genotype groups, where the phenotype indicated the severity of the hearing loss. Patients with homozygous gene changes had a more severe neurosensory phenotype. The early discovery of sensorineural hearing loss and WS is crucial since it allows intensive follow-up and treatment of the person affected from the start.

Wolfram Syndrome 1: A Pediatrician's and Pediatric Endocrinologist's Perspective

Wolfram syndrome 1 (WS1) is a rare autosomal recessive neurodegenerative disease caused by mutations in WFS1 and WFS2 genes that produce wolframin, a protein involved in endoplasmic reticulum calcium homeostasis and cellular apoptosis. Its main clinical features are diabetes insipidus (DI), early-onset non-autoimmune insulin-dependent diabetes mellitus (DM), gradual loss of vision due to optic atrophy (OA) and deafness (D), hence the acronym DIDMOAD. Several other features from different systems have been reported such as urinary tract, neurological, and psychiatric abnormalities. In addition, endocrine disorders that can appear during childhood and adolescence include primary gonadal atrophy and hypergonadotropic hypogonadism in males and menstrual cycle abnormalities in females. Further, anterior pituitary dysfunction with deficient GH and/or ACTH production have been described. Despite the lack of specific treatment for the disease and its poor life expectancy, early diagnosis and supportive care is important for timely identifying and adequately managing its progressive symptoms. The current narrative review focuses on the pathophysiology and the clinical features of the disease, with a special emphasis on its endocrine abnormalities that appear during childhood and adolescence. Further, therapeutic interventions that have been proven to be effective in the management of WS1 endocrine complications are discussed.

Delineating Wolfram-like syndrome: A systematic review and discussion of the WFS1-associated disease spectrum

Wolfram-like syndrome (WFLS) is a recently described autosomal dominant disorder with phenotypic similarities to autosomal recessive Wolfram syndrome (WS), including optic atrophy, hearing impairment, and diabetes mellitus. We summarize current literature, define the clinical characteristics, and investigate potential genotype phenotype correlations. A systematic literature search was conducted in electronic databases Pubmed/MEDLINE, EMBACE, and Cochrane Library. We included studies reporting patients with a clinical picture consisting at least 2 typical clinical manifestations of WSF1 disorders and heterozygous mutations in WFS1. In total, 86 patients from 35 studies were included. The most common phenotype consisted of the combination of optic atrophy (87%) and hearing impairment (94%). Diabetes mellitus was seen in 44% of the patients. Nineteen percent developed cataract. Patients with missense mutations in WFS1 had a lower number of clinical manifestations, less chance of developing diabetes insipidus, but a younger age at onset of hearing impairment compared to patients with nonsense mutations or deletions causing frameshift. There were no studies reporting decreased life expectancy. This review shows that, within the spectrum of WFS1-associated disorders or "wolframinopathies," autosomal dominantly inherited WFLS has a relatively mild phenotype compared to autosomal recessive WS. The clinical manifestations and their age at onset are associated with the specific underlying mutations in the WFS1 gene.

A novel WFS1 variant associated with severe diabetic retinopathy in Wolfram syndrome type 1

BACKGROUND

Wolfram syndrome type 1 is a rare neurodegenerative disorder including diabetes insipidus, diabetes mellitus, optic atrophy, and deafness, with variable additional findings. The phenotypic spectrum is very heterogeneous, with non-autoimmune juvenile-onset diabetes and optic atrophy as minimal criteria for the diagnosis. Biallelic mutations in the WFS1 gene are the causative genetic anomaly for the syndrome, with, however, no evident genotype-phenotype correlation. Among the clinical features of the disease, diabetic retinopathy depicts a rarely reported microvascular complication. In this report, we describe the clinical and genetic findings in a 26-year-old patient presenting with Wolfram syndrome and severe diabetic retinopathy.

METHODS

The mutation screening was performed by polymerase chain reaction followed by Sanger sequencing of the entire coding sequence of the WFS1 gene.

RESULTS

A novel homozygous missense variant c.1901A>T (p.Lys634Met) was found in the proband and classified as probably pathogenic according to the American College of Medical Genetics and Genomics.

CONCLUSIONS

The molecular study of the WFS1 gene is essential for the diagnostic confirmation, to provide appropriate genetic counseling and a mutational screening in the at-risk relatives. The c.1901A>T (p.Lys634 Met) is a novel variant that could be responsible for a severe form of Wolfram syndrome with early and proliferative diabetic retinopathy.

WFS1-Associated Optic Neuropathy: Genotype-Phenotype Correlations and Disease Progression

OBJECTIVE

To evaluate the pattern of vision loss and genotype-phenotype correlations in WFS1-associated optic neuropathy (WON).

DESIGN

Multicenter cohort study.

METHODS

The study involved 37 patients with WON carrying pathogenic or candidate pathogenic WFS1 variants. Genetic and clinical data were retrieved from the medical records. Thirteen patients underwent additional comprehensive ophthalmologic assessment. Deep phenotyping involved visual electrophysiology and advanced psychophysical testing with a complementary metabolomic study.

MAIN OUTCOME MEASURES

WFS1 variants, functional and structural optic nerve and retinal parameters, and metabolomic profile.

RESULTS

Twenty-two recessive and 5 dominant WFS1 variants were identified. Four variants were novel. All WFS1 variants caused loss of macular retinal ganglion cells (RGCs) as assessed by optical coherence tomography (OCT) and visual electrophysiology. Advanced psychophysical testing indicated involvement of the major RGC subpopulations. Modeling of vision loss showed an accelerated rate of deterioration with increasing age. Dominant WFS1 variants were associated with abnormal reflectivity of the outer plexiform layer (OPL) on OCT imaging. The dominant variants tended to cause less severe vision loss compared with recessive WFS1 variants, which resulted in more variable phenotypes ranging from isolated WON to severe multisystem disease depending on the WFS1 alleles. The metabolomic profile included markers seen in other neurodegenerative diseases and type 1 diabetes mellitus.

CONCLUSIONS

WFS1 variants result in heterogenous phenotypes influenced by the mode of inheritance and the disease-causing alleles. Biallelic WFS1 variants cause more variable, but generally more severe, vision and RGC loss compared with heterozygous variants. Abnormal cleftlike lamination of the OPL is a distinctive OCT feature that strongly points toward dominant WON.

Wolfram Syndrome: A case report of two sisters Wolfram Syndrome: Case report of two sisters

PURPOSE

To present a case of two siblings with optic atrophy associated with Wolfram Syndrome.

OBSERVATIONS

Two young adult siblings presented with serious bilateral loss of vision and dyschromatopsia established in early adolescence. They were referred with a presumed diagnosis of Leber's Hereditary Optic Neuropathy. At baseline, visual acuity was 20/400 in the right eye and 20/200 in the left eye in patient A and 20/200 in both eyes in patient B, color perception tested with pseudo-isochromatic plates was 0/17 in each eye, optic discs were pale, visual field testing revealed diffuse scotomas bilaterally while electrophysiology showed delayed prominent positive deflection (P100) values in both patients. Personal history revealed Type 1 diabetes mellitus since early childhood. Patients were lost to follow-up and presented 4 years later with significant VA decrease (<20/400) and suspected hearing loss. At that point, genetic testing revealed a pathogenic variation in the WFS1 gene thus confirming the diagnosis of Wolfram syndrome. Treatment with idebenone was proposed, to which only one of the siblings agreed. The other patient remained under observation, as no known treatment for optic atrophy in Wolfram syndrome exists to date.

CONCLUSIONS AND IMPORTANCE

Wolfram syndrome is a rare neurodegenerative genetic disease associated with diabetes mellitus, optic atrophy and deafness. Careful and detailed medical and family history led to appropriate testing that confirmed the diagnosis of Wolfram syndrome. To this day, there is no definite treatment for this disease, but the experimental use of idebenone has been suggested to improve visual function. Genetic testing of family members and offspring of patients is strongly recommended.

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.

Late‐onset hearing loss case associated with a heterozygous truncating variant of DIAPH1

Diaphanous-related formin 1 (DIAPH1) is a formin homology F-actin elongating protein encoded by DIAPH1. Homozygous recessive variants resulting in the loss of DIAPH1 function cause seizures, cortical blindness, and microcephaly syndrome (SCBMS), but hearing loss has not been reported. In contrast, dominant variants of human DIAPH1 are associated with DFNA1 non-syndromic sensorineural hearing loss. The deafness phenotype is due partly to abnormal F-actin elongation activity caused by disruption of the DIAPH1 autoinhibitory mechanism. We report an elderly female heterozygous for the c.3145C>T: p.R1049X variant who showed late-onset sensorineural hearing loss in her fifth decade. p.R1049X lacks F-actin elongation activity because this variant truncates one-third of the FH2 domain, which is vital for DIAPH1 dimerization and processive F-actin elongation activity. Concordantly, no increase of F-actin or processive F-actin elongation activity was observed after overexpression of p.R1049X DIAPH1 in HeLa cells or by single-molecule microscopy using Xenopus XTC cells. However, overexpression of the p.R1049X variant impairs formation of cell-cell junctions and mitosis. We speculate that late-onset hearing loss is a long-term consequence of heterozygosity for the recessive p.R1049X variant, a phenotype that may have been overlooked among carriers of other recessive alleles of DIAPH1.

Current Drug Repurposing Strategies for Rare Neurodegenerative Disorders

Rare diseases are life-threatening or chronically debilitating low-prevalent disorders caused by pathogenic mutations or particular environmental insults. Due to their high complexity and low frequency, important gaps still exist in their prevention, diagnosis, and treatment. Since new drug discovery is a very costly and time-consuming process, leading pharmaceutical companies show relatively low interest in orphan drug research and development due to the high cost of investments compared to the low market return of the product. Drug repurposing–based approaches appear then as cost- and time-saving strategies for the development of therapeutic opportunities for rare diseases. In this article, we discuss the scientific, regulatory, and economic aspects of the development of repurposed drugs for the treatment of rare neurodegenerative disorders with a particular focus on Huntington’s disease, Friedreich’s ataxia, Wolfram syndrome, and amyotrophic lateral sclerosis. The role of academia, pharmaceutical companies, patient associations, and foundations in the identification of candidate compounds and their preclinical and clinical evaluation will also be discussed.

WFS1 protein expression correlates with clinical progression of optic atrophy in patients with Wolfram syndrome

BACKGROUND

Wolfram syndrome (WFS) is a rare disorder characterised by childhood-onset diabetes mellitus and progressive optic atrophy. Most patients have variants in the WFS1 gene. We undertook functional studies of WFS1 variants and correlated these with WFS1 protein expression and phenotype.

METHODS

9 patients with a clinical diagnosis of WFS were studied with quantitative PCR for markers of endoplasmic reticulum (ER) stress and immunoblotting of fibroblast protein extracts for WFS1 protein expression. Luciferase reporter assay was used to assess ATF-6 dependent unfolded protein response (UPR) activation.

RESULTS

6 patients with compound heterozygous nonsense mutations in WFS1 had no detectable WFS1 protein expression; 3 patients with missense variants had 4%, 45% and 48% WFS1 protein expression. One of these also had an OPA1 mutation and was reclassified as autosomal dominant optic atrophy-plus syndrome. There were no correlations between ER stress marker mRNA and WFS1 protein expression. ERSE-luciferase reporter indicated activation of the ATF6 branch of UPR in two patients tested. Patients with partial WFS1 expression showed milder visual acuity impairment (asymptomatic or colour blind only), compared with those with absent expression (registered severe vision impaired) (p=0.04). These differences remained after adjusting for duration of optic atrophy.

CONCLUSIONS

Patients with WFS who have partial WFS1 protein expression present with milder visual impairment. This suggests a protective effect of partial WFS1 protein expression on the severity and perhaps progression of vision impairment and that therapies to increase residual WFS1 protein expression may be beneficial.

[Autosomal recessive optic neuropathies: genetic variants, clinical manifestations]

Hereditary optic neuropathies (HON) - a group of neurodegenerative diseases characterized by primary loss of structure and function of the retinal ganglion cells and subsequent death of their axons, development of partial optic nerve atrophy. Autosomal dominant optic neuropathy and Leber`s hereditary optic neuropathy until recently were considered the most common genetic hereditary optic neuropathies, while autosomal recessive optic neuropathies (ARON) were described as rare types of HON, usually accompanying severe syndromic pathologies. In the 2000s it has become clear that ARON occur significantly more often, are underestimated, and their clinical variability is poorly studied. Despite the fact that non-syndromic ARON are less common than syndromic optic neuropathies, their contribution to the development of isolated hereditary optic neuropathies should be considered. This article presents a literature review on non-syndromic ARON developing as a result of mutations in the ACO2, MCAT, WFS1, RTN4IP1, TMEM126A, NDUFS2, DNAJC30 genes.

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.

Use of Next-Generation Sequencing for the Molecular Diagnosis of 1,102 Patients With a Autosomal Optic Neuropathy

Advances in next-generation sequencing (NGS) facilitate the diagnosis of genetic disorders. To evaluate its use for the molecular diagnosis of inherited optic neuropathy (ION), a blinding disease caused by the degeneration of retinal ganglion cells, we performed genetic analysis using targeted NGS of 22 already known and candidate genes in a cohort of 1,102 affected individuals. The panel design, library preparation, and sequencing reactions were performed using the Ion AmpliSeq technology. Pathogenic variants were detected in 16 genes in 245 patients (22%), including 186 (17%) and 59 (5%) dominant and recessive cases, respectively. Results confirmed that OPA1 variants are responsible for the majority of dominant IONs, whereas ACO2 and WFS1 variants are also frequently involved in both dominant and recessive forms of ION. All pathogenic variants were found in genes encoding proteins involved in the mitochondrial function, highlighting the importance of mitochondria in the survival of retinal ganglion cells.

Molecular mechanisms of β-cell dysfunction and death in monogenic forms of diabetes

Monogenetic forms of diabetes represent 1%-5% of all diabetes cases and are caused by mutations in a single gene. These mutations, that affect genes involved in pancreatic β-cell development, function and survival, or insulin regulation, may be dominant or recessive, inherited or de novo. Most patients with monogenic diabetes are very commonly misdiagnosed as having type 1 or type 2 diabetes. The severity of their symptoms depends on the nature of the mutation, the function of the affected gene and, in some cases, the influence of additional genetic or environmental factors that modulate severity and penetrance. In some patients, diabetes is accompanied by other syndromic features such as deafness, blindness, microcephaly, liver and intestinal defects, among others. The age of diabetes onset may also vary from neonatal until early adulthood manifestations. Since the different mutations result in diverse clinical presentations, patients usually need different treatments that range from just diet and exercise, to the requirement of exogenous insulin or other hypoglycemic drugs, e.g., sulfonylureas or glucagon-like peptide 1 analogs to control their glycemia. As a consequence, awareness and correct diagnosis are crucial for the proper management and treatment of monogenic diabetes patients. In this chapter, we describe mutations causing different monogenic forms of diabetes associated with inadequate pancreas development or impaired β-cell function and survival, and discuss the molecular mechanisms involved in β-cell demise.

Collaboration for rare diabetes: understanding new treatment options for Wolfram syndrome

BACKGROUND

Wolfram Syndrome is a very rare genetic disease causing diabetes mellitus, blindness, deafness, diabetes insipidus, and progressive brainstem degeneration. Neurologic symptoms of affected patients include ataxia, sleep apnea, loss of bladder control, dysphagia, loss of taste, and accompanying psychiatric symptoms as a sign of progressive neurodegeneration. Its genetic cause is mainly biallelic mutations of the Wolframin endoplasmatic reticulum transmembrane glycoprotein gene Wfs1. These result in increased ER stress, which in turn induces apoptosis and leads to the depletion of the corresponding cells and a loss of their physiological functions. Though diabetes mellitus is mostly treated by insulin, there is still no proven cure for the disease in general. It leads to premature death in affected individuals-usually within the 4th decade of live.

CURRENT RESEARCH AND TREATMENT TRIALS

Clinical studies are currently being conducted at various locations worldwide to test a therapy for the disease using various approaches.

POTENTAIL OF VIRTUAL NETOWRKING

As rare diseases in general represent a major challenge for individual clinicians and researchers due to the rarity of diagnosis, the lack of evidence and of value of existing research, international cooperation, coordination and networking leading to an alignment of different stakeholders is necessary to support patients and increase knowledge about these diseases, like wolfram syndrome.

CONCLUSION

ENDO-ERN and EURRECA are two EU-funded networks that aim to promote knowledge sharing, education and research on rare endocrine diseases.

The Impact of Mutations in Wolframin on Psychiatric Disorders

Wolfram Syndrome is a rare autosomal recessive disease characterized by early-onset diabetes mellitus, neurodegeneration, and psychological disorders. Mutations in the gene WFS1, coding for the protein wolframin, cause Wolfram Syndrome and are associated with bipolar disorder and schizophrenia. This report aims to connect WFS1 mutations to their impact on protein expression and structure, which ultimately translates to altered cell function and behavioral alterations of an individual. Methods: Published data were used to compile WFS1 mutations associated with psychiatric symptoms, both in homozygous patients and heterozygous carriers of WFS1 mutations. These mutations were evaluated in silico using SNAP2, PolyPhen-2, and PROVEAN to predict the effects of sequence variants. Statistical analysis was performed to assess the correlation between the locations of the mutations and the damage prediction scores. Results: Several mutations, clustering in the center and C-terminus of the WFS1 polypeptide, such as A559T and R558C, are found in individuals with psychiatric diseases and appear particularly impactful on protein structure. Our analysis showed that mutations in all regions of wolframin were present in patients with schizophrenia whereas only cytoplasmic and ER luminal mutations were reported in patients with manic episodes and bipolar disorders. According to Poly-Phen-2 predictions, 82.4% of the ER lumen mutations and 85.7% of the membrane mutations are damaging. Conclusion: We propose mood disorders in Wolfram Syndrome and heterozygous carriers of WFS1 mutations are the consequence of specific mutations in WFS1 that alter the structure of wolframin, resulting in intracellular calcium dysregulations and impaired cell signaling, Understanding the effect of WFS1 mutations on bipolar disorder and schizoprenia is integral to designing clinically targeted treatments for both diseases, which need more specialized treatments.

Neuro-ophthalmic manifestations of mitochondrial disorders and their management

The visual system has high metabolic requirements and is therefore particularly vulnerable to mitochondrial dysfunction. The most commonly affected tissues include the extraocular muscles, photoreceptors, retinal pigment epithelium, optic nerve and visual cortex. Hence, the most common manifestations of mitochondrial disorders are progressive external ophthalmoplegia, macular pattern dystrophy, pigmentary retinopathy, optic neuropathy and retrochiasmal visual field loss. With the exception of Leber hereditary optic neuropathy and stroke-like episodes seen in mitochondrial encephalopathy, lactic acidosis and stroke-like episodes, the majority of neuro-ophthalmic manifestations have an insidious onset. As such, some patients may not recognize subtle progressive visual symptoms. When mitochondrial disorders are highly suspected, meticulous examination performed by an ophthalmologist with targeted ancillary testing can help confirm the diagnosis. Similarly, neuro-ophthalmic symptoms and signs may be the first indication of mitochondrial disease and should prompt systemic investigations for potentially life-threatening associations, such as cardiac conduction defects. Finally, the ophthalmologist can offer symptomatic treatments for some of the most disabling manifestations of these disorders.

Autosomal-dominant WFS1-related disorder-Report of a novel WFS1 variant and review of the phenotypic spectrum of autosomal recessive and dominant forms

Wolfram syndrome was initially reported as an autosomal recessive (AR), progressive neurodegenerative disorder that leads to diabetes insipidus, childhood onset diabetes mellitus (DM), optic atrophy, and deafness (D) also known as DIDMOAD. However, heterozygous dominant pathogenic variants in Wolfram syndrome type 1 (WFS1) may lead to distinct, allelic conditions, described as isolated sensorineural hearing loss (SNHL), syndromic SNHL, congenital cataracts, or early onset DM. We report a family with a novel dominant, likely pathogenic variant in WFS1 (NM_006005.3) c.2605_2616del12 (p.Ser869_His872del), resulting in cataracts, SNHL, and DM in a female and her mother. A maternal aunt had cataracts, DM, and SNHL but was not tested for the familial WFS1 mutation. Both the mother and maternal aunt had early menopause by age 43 years and infertility which may be a coincidental finding that has not been associated with autosomal dominant AD WFS1-related disorder to the best of our knowledge. Screening at risk individuals in families with the AR Wolfram syndrome, for DM, SNHL, and for cataracts is indicated.

Effect of 4-phenylbutyrate and valproate on dominant mutations of WFS1 gene in Wolfram syndrome

PURPOSE

Wolfram syndrome (WS) is a rare disorder caused by mutations in WFS1 that is characterized by diabetes mellitus, optic atrophy, sensorineural deafness, diabetes insipidus, and neurodegeneration. This disease is usually inherited as an autosomal recessive trait, but an autosomal dominant form has been reported. WFS1 encodes a transmembrane protein, which is a maintenance component of endoplasmic homeostasis. These dominant mutations were thought to increase endoplasmic reticulum (ER) stress. Recent studies suggest that 4-phenylbutyrate (PBA) and valproate (VPA) reduce ER stress. The objective of this study was to analyze the effect of PBA and VPA on dominant WFS1 mutants in vitro.

METHODS

We determined whether dominant WFS1 mutants (p.His313Tyr, p.Trp314Arg, p.Asp325_Ile328del, p.Glu809Lys, and p.Glu864Lys) have the dominant negative effect using a luciferase assay of ER stress response element marker as ER stress. Moreover, the rescue of cell apoptosis induced by dominant WFS1 mutants following treatment with PBA or VPA was determined by quantitative real-time PCR of C/EBP homologous protein (CHOP) mRNA expression.

RESULTS

These mutants showed the dominant negative effect on the wild-type WFS1. In addition, the levels of ER stress and CHOP mRNA were significantly elevated by all dominant WFS1 mutants. After treatment with PBA or VPA, ER stress and cell apoptosis were reduced in each mutant.

CONCLUSIONS

PBA and VPA could reduce the ER stress and cell apoptosis caused by dominant WFS1 mutants.

Recurrent de novo WFS1 pathogenic variants in Chinese sporadic patients with nonsyndromic sensorineural hearing loss

Background

Hereditary hearing loss (HL) is heterogeneous in terms of their phenotypic features, modes of inheritance, and causative gene mutations. The contribution of genetic variants to sporadic HL remains largely expanding. Either recessive or de novo dominant variants could result in an apparently sporadic occurrence of HL. In an attempt to find such variants we recruited 128 Chinese patients with sporadic nonsyndromic sensorineural HL (NSHL) and performed targeted deafness multigene sequencing in these unrelated trios‐families to elucidate the molecular basis.

Methods

We analyzed a total of 384 available members (probands and their two parents) from 128 unrelated Chinese families presenting with bilateral sensorineural HL, in which previous screening had found no mutations with the GJB2, SLC26A4, and MT‐RNR1 genes. We used a targeted genomic enrichment platform to simultaneously capture exons, splicing sites, and immediate flanking intron sequences of 127 known deafness genes. Sanger sequencing was used to identify probands and their two parents segregating causative variants in the candidate gene.

Results

We observed that two heterozygous de novo WFS1 mutations in exon 8: c.2051C>T (p.A684V) and c.2590G>A (p.E864K) in five families. The two de novo WFS1 mutations were found in 3.9% (5/128) of sporadic HL patients. We found that four of the five patients had the same de novo p.A684V mutation, and their audiograms showed symmetrical bilateral and profound sensorineural hearing impairments at all frequencies, but only the proband with de novo p.E864K mutation demonstrated significantly bilateral moderate low–mid frequency sensorineural HL. Our data suggest that this WFS1 p.A684V is likely to be a de novo mutational hot spot.

Conclusions

We found 3.9% (5/128) of sporadic NSHL is caused by de novo WFS1 mutations. Our data provide that the de novo p.E864K mutation is first identified and de novo p.A684V mutation is likely to be a mutational hot spot in WFS1. It is the first study to highlight that WFS1 gene with the two de novo mutations has been indicated to classify the distinct hearing impairment phenotypes. Furthermore, de novo p.A684V serves as a WFS1 mutational hot spot that was found in the Chinese population with sporadic childhood NSHL, and our study also provides pointers toward the necessity for sequencing of asymptomatic parents of a sporadic case with an apparent dominant pathogenic variant.

Novel mutations and the ophthalmologic characters in Chinese patients with Wolfram Syndrome

BACKGROUND

Wolfram Syndrome (WFS) is a rare autosomal recessive neurodegenerative disease which has a wide spectrum of manifestations including diabetes insipidus, diabetes mellitus, optic atrophy and deafness. WFS1 and CISD2 are two main causing genes of WFS. The aim of this study was to illustrate the ophthalmologic manifestations and determine the genotype of Chinese WFS patients.

RESULTS

Completed ophthalmic examinations and family investigations were performed on 4 clinically diagnosed WFS patients from 4 unrelated families. Genetic testing was done by the next generation sequencing of candidate genes. One patient carried a homozygous mutation (c.272_273del) in CISD2, two patients carried compound heterozygous mutations (c.1618 T > G + c.2020G > A and c.1048 T > A + c.2020G > A) in WFS1, and one patient carried a heterozygous mutation (c.937C > T) in WFS1. Three of them were novel mutations.

CONCLUSIONS

Our study indicated WFS in Chinese is a neurodegenerative disease with both wide spectrum of clinical features and genetic heterogeneity. We found three novel mutations in WFS patients, and to our best knowledge, this is the first report of Chinese WFS patient with mutation in CISD2.

Wolfram syndrome, a rare neurodegenerative disease: from pathogenesis to future treatment perspectives

Background

Wolfram syndrome (WS), a rare genetic disorder, is considered the best prototype of endoplasmic reticulum (ER) diseases. Classical WS features are childhood-onset diabetes mellitus, optic atrophy, deafness, diabetes insipidus, neurological signs, and other abnormalities. Two causative genes (WFS1 and WFS2) have been identified. The transmission of the disease takes place in an autosomal recessive mode but autosomal dominant mutations responsible for WS-related disorders have been described. Prognosis is poor, death occurs at the median age of 39 years with a major cause represented by respiratory failure as a consequence of brain stem atrophy and neurodegeneration. The aim of this narrative review is to focus on etiology, pathogenesis and natural history of WS for an adequate patient management and for the discussion of future therapeutic interventions.

Main body

WS requires a multidisciplinary approach in order to be successfully treated. A prompt diagnosis decreases morbidity and mortality through prevention and treatment of complications. Being a monogenic pathology, WS represents a perfect model to study the mechanisms of ER stress and how this condition leads to cell death, in comparison with other prevalent diseases in which multiple factors interact to produce the disease manifestations. WS is also an important disease prototype to identify drugs and molecules associated with ER homeostasis. Evidence indicates that specific metabolic diseases (type 1 and type 2 diabetes), neurodegenerative diseases, atherosclerosis, inflammatory pathologies and also cancer are closely related to ER dysfunction.

Conclusions

Therapeutic strategies in WS are based on drug repurposing (i.e., investigation of approved drugs for novel therapeutic indications) with the aim to stop the progression of the disease by reducing the endoplasmic reticulum stress. An extensive understanding of WS from pathophysiology to therapy is fundamental and more studies are necessary to better manage this devastating disease and guarantee the patients a better quality of life and longer life expectancy.

Whole exome sequencing in adult-onset hearing loss reveals a high load of predicted pathogenic variants in known deafness-associated genes and identifies new candidate genes

Background

Deafness is a highly heterogenous disorder with over 100 genes known to underlie human non-syndromic hearing impairment. However, many more remain undiscovered, particularly those involved in the most common form of deafness: adult-onset progressive hearing loss. Despite several genome-wide association studies of adult hearing status, it remains unclear whether the genetic architecture of this common sensory loss consists of multiple rare variants each with large effect size or many common susceptibility variants each with small to medium effects. As next generation sequencing is now being utilised in clinical diagnosis, our aim was to explore the viability of diagnosing the genetic cause of hearing loss using whole exome sequencing in individual subjects as in a clinical setting.

Methods

We performed exome sequencing of thirty patients selected for distinct phenotypic sub-types from well-characterised cohorts of 1479 people with adult-onset hearing loss.

Results

Every individual carried predicted pathogenic variants in at least ten deafness-associated genes; similar findings were obtained from an analysis of the 1000 Genomes Project data unselected for hearing status. We have identified putative causal variants in known deafness genes and several novel candidate genes, including NEDD4 and NEFH that were mutated in multiple individuals.

Conclusions

The high frequency of predicted-pathogenic variants detected in known deafness-associated genes was unexpected and has significant implications for current diagnostic sequencing in deafness. Our findings suggest that in a clinic setting, efforts should be made to a) confirm key sequence results by Sanger sequencing, b) assess segregations of variants and phenotypes within the family if at all possible, and c) use caution in applying current pathogenicity prediction algorithms for diagnostic purposes. We conclude that there may be a high number of pathogenic variants affecting hearing in the ageing population, including many in known deafness-associated genes. Our findings of frequent predicted-pathogenic variants in both our hearing-impaired sample and in the larger 1000 Genomes Project sample unselected for auditory function suggests that the reference population for interpreting variants for this very common disorder should be a population of people with good hearing for their age rather than an unselected population.

Electronic supplementary material

The online version of this article (10.1186/s12920-018-0395-1) contains supplementary material, which is available to authorized users.

Longitudinal hearing loss in Wolfram syndrome

BACKGROUND

Wolfram syndrome (WFS) is a rare autosomal recessive disease with clinical manifestations of diabetes mellitus (DM), diabetes insipidus (DI), optic nerve atrophy (OA) and sensorineural hearing loss (SNHL). Although SNHL is a key symptom of WFS, there is limited information on its natural history using standardized measures. Such information is important for clinical care and determining its use as an outcome measure in clinical trials.

METHODS

Standardized audiologic measures, including pure-tone testing, tympanometry, speech perception, and the unaided Speech Intelligibility Index (SII) were assessed in patients with confirmed WFS annually. Mixed model analyses were used to examine main effects of age, time or interactions for pure tone average (PTA), high frequency average (HFA) and SII.

RESULTS

Forty WFS patients were evaluated between 1 and 6 times. Mean age at initial enrollment was 13.5 years (SD = 5.6). Patients were classified as having normal hearing (n = 10), mild-to-severe (n = 24) or profound SNHL (n = 6). Mean age of diagnosis for SNHL was 8.3 years (SD = 5.1) with 75% prevalence. HFA worsened over time for both ears, and SII worsened over time in the worse ear, with greater decline in both measures in younger patients. Average estimated change over 1 year for all measures was in the subclinical range and power analyses suggest that 100 patients would be needed per group (treatment vs. placebo) to detect a 60% reduction in annual change of HFA over 3 years. If trials focused on just those patients with SNHL, power estimates suggest 55 patients per group would be sufficient.

CONCLUSIONS

Most patients had a slow progressive SNHL emerging in late childhood. Change over time with standard audiologic tests (HFA, SII) was small and would not be detectable for at least 2 years in an individual. Relatively large sample sizes would be necessary to detect significant impact on hearing progression in a clinical trial. Hearing function should be monitored clinically in WFS to provide appropriate intervention. Because SNHL can occur very early in WFS, audiologists and otolaryngologists should be aware of and refer for later emerging symptoms.

Bladder dysfunction in Wolfram syndrome is highly prevalent and progresses to megacystis

AIM

Wolfram syndrome is a rare genetic defect in WFS1 or WSF2(CISD2). It includes diabetes mellitus and insipidis, sensorineural deafness, optic atrophy, but not bladder dysfunction. However, this has appeared a common finding in our national referral clinic, and we sought to quantify this problem.

METHODS

Data were collected from a multidisciplinary team managing all Wolfram patients in the UK. The following was analyzed: age, date of non-invasive urodynamics (NIU), symptoms, bladder capacity, voided volume, post-void residual and uroflow pattern. Bladder capacity was given as percentage predicted bladder capacity (PBC). Bladders were divided into normal, overactive (OAB), and underactive (UAB). Symptoms, bladder behavior, and genotyping were correlated. Data were expressed as median (interquartile range).

MAIN RESULTS

Forty patients with Wolfram syndrome were identified, and 38 underwent NIU. This showed normal bladder function (n=4), OAB (n=9), UAB (n=25). Symptoms were present in only 11 children. The different patterns of bladder behavior (OAB vs. normal vs. UAB) were significantly associated with different %PBC (36 (29-59)% vs. 105 (93-233)% vs. 100 (77.5-337)%; p<0.001), and percentage emptying (100 (80-100)% vs. 100 (87-100)% vs. 69 (48-93)%; p<0.05). There was no association of genotype, symptoms and bladder behavior. Patients with megacystis were older: [13.4 (9.7-16.1) vs. 15.4 (13.9-18.7) years; p<0.05).

CONCLUSION

Bladder dysfunction is very common in Wolfram syndrome (~90%), but most children cope (symptoms ~30%). With time there is a significant progression to megacystis, which may represent an underlying neuropathic myogenic failure and is likely to require intervention in the future.

LEVEL OF EVIDENCE

Level II (National cohort study of prognosis).

A novel heterozygous mutation of the WFS1 gene leading to constitutive endoplasmic reticulum stress is the cause of Wolfram syndrome

BACKGROUND

Wolfram syndrome (WS) is a disorder characterized by the association of insulin-dependent diabetes mellitus (DM), diabetes insipidus, deafness, and optic nerve atrophy. WS is caused by WFS1 mutations encoding WFS1 protein expressed in endoplasmic reticulum (ER). During ER protein synthesis, misfolded and unfolded proteins accumulate, known as "ER stress". This is attenuated by the unfolded protein response (UPR), which recovers and maintains ER functions. Because WFS1 is a UPR component, mutant WFS1 might cause unresolvable ER stress conditions and cell apoptosis, the major causes underlying WS symptoms. We encountered an 11-month-old Japanese female WS patient with insulin-dependent DM, congenital cataract and severe bilateral hearing loss.

OBJECTIVE

Analyze the WFS1 and functional consequence of the patient WFS1 in vitro.

RESULTS

The patient WFS1 contained a heterozygous 4 amino acid in-frame deletion (p.N325_I328del). Her mutant WFS1 increased GRP78 and ATF6α promoter activities in the absence of thapsigargin, indicating constitutive ER stress and nuclear factor of activated T-cell reporter activity, reflecting elevated cytosolic Ca²⁺ signals. Mutant transfection into cells reduced mRNA expression levels of sarcoplasmic/endoplasmic reticulum Ca²⁺ transport ATPase 2b (SERCA2b) compared with wild type. Because SERCA2b is required for ER and cytoplasmic Ca²⁺ homeostasis, decreased SERCA2b expression might affect ER Ca²⁺ efflux, causing cell apoptosis.

CONCLUSION

A novel heterozygous mutation of WFS1 induced constitutive ER stress through ATF6α activation and ER Ca²⁺ efflux, resulting in cell apoptosis. These results provide new insights into the roles of WFS1 in UPR and mechanism of monogenic DM.

Genetic Testing for Wolfram Syndrome Mutations in a Sample of 71 Patients with Hereditary Optic Neuropathy and Negative Genetic Test Results for OPA1/OPA3/LHON

In this study, the authors present a sample of 71 patients with hereditary optic neuropathy and negative genetic test results for OPA1/OPA3/LHON. All of these patients later underwent genetic testing to rule out WFS. As a result, 53 patients (74.7%) were negative and 18 patients (25.3%) were positive for some type of mutation or variation in the WFS gene. The authors believe that this study is interesting because it shows that a sizeable percentage (25.3%) of patients with hereditary optic 25 neuropathy and negative genetic test results for OPA1/OPA3/LHON had WFS mutations or variants.

Dominant ER Stress-Inducing WFS1 Mutations Underlie a Genetic Syndrome of Neonatal/Infancy-Onset Diabetes, Congenital Sensorineural Deafness, and Congenital Cataracts

Neonatal diabetes is frequently part of a complex syndrome with extrapancreatic features: 18 genes causing syndromic neonatal diabetes have been identified to date. There are still patients with neonatal diabetes who have novel genetic syndromes. We performed exome sequencing in a patient and his unrelated, unaffected parents to identify the genetic etiology of a syndrome characterized by neonatal diabetes, sensorineural deafness, and congenital cataracts. Further testing was performed in 311 patients with diabetes diagnosed before 1 year of age in whom all known genetic causes had been excluded. We identified 5 patients, including the initial case, with three heterozygous missense mutations in WFS1 (4/5 confirmed de novo). They had diabetes diagnosed before 12 months (2 before 6 months) (5/5), sensorineural deafness diagnosed soon after birth (5/5), congenital cataracts (4/5), and hypotonia (4/5). In vitro studies showed that these WFS1 mutations are functionally different from the known recessive Wolfram syndrome-causing mutations, as they tend to aggregate and induce robust endoplasmic reticulum stress. Our results establish specific dominant WFS1 mutations as a cause of a novel syndrome including neonatal/infancy-onset diabetes, congenital cataracts, and sensorineural deafness. This syndrome has a discrete pathophysiology and differs genetically and clinically from recessive Wolfram syndrome.

Monogenic diabetes syndromes: Locus-specific databases for Alström, Wolfram, and Thiamine-responsive megaloblastic anemia

We developed a variant database for diabetes syndrome genes, using the Leiden Open Variation Database platform, containing observed phenotypes matched to the genetic variations. We populated it with 628 published disease-associated variants (December 2016) for: WFS1 (n = 309), CISD2 (n = 3), ALMS1 (n = 268), and SLC19A2 (n = 48) for Wolfram type 1, Wolfram type 2, Alström, and Thiamine-responsive megaloblastic anemia syndromes, respectively; and included 23 previously unpublished novel germline variants in WFS1 and 17 variants in ALMS1. We then investigated genotype-phenotype relations for the WFS1 gene. The presence of biallelic loss-of-function variants predicted Wolfram syndrome defined by insulin-dependent diabetes and optic atrophy, with a sensitivity of 79% (95% CI 75%-83%) and specificity of 92% (83%-97%). The presence of minor loss-of-function variants in WFS1 predicted isolated diabetes, isolated deafness, or isolated congenital cataracts without development of the full syndrome (sensitivity 100% [93%-100%]; specificity 78% [73%-82%]). The ability to provide a prognostic prediction based on genotype will lead to improvements in patient care and counseling. The development of the database as a repository for monogenic diabetes gene variants will allow prognostic predictions for other diabetes syndromes as next-generation sequencing expands the repertoire of genotypes and phenotypes. The database is publicly available online at https://lovd.euro-wabb.org.

Endoplasmic Reticulum (ER) Stress and Endocrine Disorders

The endoplasmic reticulum (ER) is the organelle where secretory and membrane proteins are synthesized and folded. Unfolded proteins that are retained within the ER can cause ER stress. Eukaryotic cells have a defense system called the “unfolded protein response” (UPR), which protects cells from ER stress. Cells undergo apoptosis when ER stress exceeds the capacity of the UPR, which has been revealed to cause human diseases. Although neurodegenerative diseases are well-known ER stress-related diseases, it has been discovered that endocrine diseases are also related to ER stress. In this review, we focus on ER stress-related human endocrine disorders. In addition to diabetes mellitus, which is well characterized, several relatively rare genetic disorders such as familial neurohypophyseal diabetes insipidus (FNDI), Wolfram syndrome, and isolated growth hormone deficiency type II (IGHD2) are discussed in this article.

Identification of four novel mutations of the WFS1 gene in Iranian Wolfram syndrome pedigrees

AIMS

Wolfram syndrome is a rare neurodegenerative disorder with an autosomal recessive pattern of inheritance characterized by various clinical manifestations. The related gene, WFS1, encodes a transmembrane glycoprotein, named wolframin. Genetic analyses demonstrated that mutations in this gene are associated with WS type 1. Our aim in this study was to sequence WFS1 coding region in Iranian Wolfram syndrome pedigrees.

METHODS

Genomic DNA was extracted from peripheral blood of 12 WS patients and their healthy parents. Exons 2-8 and the exon-intron junctions of WFS1 were sequenced. DNA sequences were compared to the reference using Sequencher software.

RESULTS

Molecular analysis of WFS1 revealed six different mutations. Four novel and two previously reported mutations were identified. One novel mutation, c.1379_1381del, is predicted to produce an aberrant protein. A second novel mutation, c.1384G > T, encodes a truncated protein. Novel mutation, c.1097-1107dup (11 bp), causes a frameshift which results in a premature stop codon. We screened for the novel missense mutation, c.1010C > T, in 100 control alleles. This mutation was not found in any of the healthy controls.

CONCLUSION

Our study increased the spectrum of WFS1 mutations and supported the role of WFS1 in susceptibility to WS. We hope that these findings open new horizons to future molecular investigations which may help to prevent and treat this devastating disease.

Mitochondrial dysfunction and diabetic retinopathy

Mitochondrial dysfunction may predispose to the development of diabetes mellitus with the accompanying risk for developing diabetic retinopathy or may contribute directly to the diabetic metabolic dysregulation and thereby increase the risk of diabetic late complications including retinopathy. Diabetes mellitus in mitochondrial disease can lead to the development of vision threatening retinopathy, but visual acuity is often reduced secondary to neurological deficits resulting from the mitochondrial dysfunction. The relation between mitochondrial disease and diabetic retinopathy can be influenced by epigenetics where factors in the environment modify the expression of regulatory proteins coding for the elimination of reactive oxygen species.

Identification of a novel WFS1 homozygous nonsense mutation in Jordanian children with Wolfram syndrome

Wolfram syndrome (WS) is a rare autosomal recessive neurodegenerative disorder characterized by the presentation of early onset type I diabetes mellitus and optic atrophy with later onset diabetes insipidus and deafness. WFS1 gene was identified on chromosome 4p16.1 as the gene responsible for WS disease given that most of the WS patients were found to carry mutations in this gene. This study was carried out to investigate the molecular spectrum of WFS1 gene in Jordanian families. Molecular and clinical characterization was performed on five WS patients from two unrelated Jordanian families. Our data indicated that WS patients of the first family harbored two deletion mutations (V415del and F247fs) located in exon 8 and exon 7 respectively, with a compound heterozygous pattern of inheritance; while in the second family, we identified a novel nonsense mutation (W185X) located in exon 5 in the N-terminal cytoplasmic domain with a homozygous pattern of inheritance. This mutation can be considered as loss of function mutation since the resulting truncated protein lost both the transmembrane domain and the C-terminal domain. Additionally, the W185X mutation lies within the CaM binding domain in wolframin protein which is thought to have a role in the regulation of wolframin function in response to calcium levels.

Wolfram Syndrome: Diagnosis, Management, and Treatment

Wolfram syndrome is a rare genetic disorder characterized by juvenile-onset diabetes mellitus, diabetes insipidus, optic nerve atrophy, hearing loss, and neurodegeneration. Although there are currently no effective treatments that can delay or reverse the progression of Wolfram syndrome, the use of careful clinical monitoring and supportive care can help relieve the suffering of patients and improve their quality of life. The prognosis of this syndrome is currently poor, and many patients die prematurely with severe neurological disabilities, raising the urgency for developing novel treatments for Wolfram syndrome. In this article, we describe natural history and etiology, provide recommendations for diagnosis and clinical management, and introduce new treatments for Wolfram syndrome.

Effects of Zhichan powder on signal transduction and apoptosis-associated gene expression in the substantia nigra of Parkinson's disease rats

Previous studies have shown that Zhichan powder elevated immunity and suppressed oxidation in mice. Rat models of Parkinson’s disease were induced by stereotaxically injecting 6-hydroxydopamine into the substantia nigra. The rat models were intragastrically treated with Zhichan powder, which is composed of milkvetch root, ginseng, bunge swallowwort root, himalayan teasel root, Magnolia officinalis, Ligustrum lucidum Ait. and szechwan lovage rhizome. Immunohistochemistry and reverse transcription-PCR results demonstrated that mRNA and protein expression of tumor necrosis factor receptor 1, Fas, caspase-8, cytochrome C, Bax, caspase-3, and p53 significantly increased, but Bcl-2 expression significantly decreased in the substantia nigra of rats with Parkinson’s disease. Following Zhichan powder administration, mRNA and protein expression of tumor necrosis factor receptor 1, Fas, caspase-8, cytochrome C, Bax, caspase-3, and p53 diminished, but Bcl-2 expression increased in the rat substantia nigra. These results indicate that Zhichan powder regulates signal transduction protein expression, inhibits apoptosis, and exerts therapeutic effects on Parkinson’s disease.

A Challenging Form of Non-autoimmune Insulin-Dependent Diabetes in a Wolfram Syndrome Patient with a Novel Sequence Variant

Wolfram syndrome type 1 is a rare, autosomal recessive, neurodegenerative disorder that is diagnosed when insulin-dependent diabetes of non-auto-immune origin and optic atrophy are concomitantly present. Wolfram syndrome is also designated by DIDMOAD that stands for its most frequent manifestations: diabetes insipidus, diabetes mellitus, optic atrophy and deafness. With disease progression, patients also commonly develop severe neurological and genito-urinary tract abnormalities. When compared to the general type 1 diabetic population, patients with Wolfram Syndrome have been reported to have a form of diabetes that is more easily controlled and with less microvascular complications, such as diabetic retinopathy.

We report a case of Wolfram syndrome in a 16-year-old male patient who presented with progressive optic atrophy and severe diabetes with very challenging glycemic control despite intensive therapy since diagnosis at the age of 6. Despite inadequate metabolic control he did not develop any diabetic microvascular complications during the 10-year follow-up period. To further investigate potential causes for this metabolic idiosyncrasy, we performed genetic analyses that revealed a novel combination of homozygous sequence variants that are likely the cause of the syndrome in this family. The identified genotype included a novel sequence variant in the Wolfram syndrome type 1 gene along with a previously described one, which had initially been associated with isolated low frequency sensorineural hearing loss (LFSNHL). Interestingly, our patient did not show any abnormal findings with audiometry testing.

Audiologic and vestibular findings in Wolfram syndrome

OBJECTIVES

Assessment of auditory and vestibular function in Wolfram Syndrome (WS) patients, using a standardized protocol.

DESIGN

Prospective cohort study of 11 patients using otoscopic inspection, tympanometry, otoacoustic emissions, pure tones, speech in noise (SIN), the Speech Intelligibility Index, and rotational chair testing.

RESULTS

Mean SNHL diagnosis was 7.3 years with 55% prevalence. Four patients with a Speech Intelligibility Index less than 0.75 (better ear) routinely used bilateral amplification devices. Two patients with normal-hearing sensitivity exhibited abnormal SIN scores. The only patient with significant vestibular dysfunction also had a distinctive low-frequency component to her SNHL.

CONCLUSIONS

Hearing loss may occur earlier than previously suspected, and comprehensive testing including SIN testing may reveal deficits not apparent with pure-tone testing. Particular configurations of hearing loss may indicate a need for comprehensive vestibular assessment. Because SNHL can be the first symptom of WS, audiologists and otolaryngologists should be vigilant about referring patients with hearing loss for ophthalmologic examination.

Calcium efflux from the endoplasmic reticulum leads to β-cell death

It has been established that intracellular calcium homeostasis is critical for survival and function of pancreatic β-cells. However, the role of endoplasmic reticulum (ER) calcium homeostasis in β-cell survival and death is not clear. Here we show that ER calcium depletion plays a critical role in β-cell death. Various pathological conditions associated with β-cell death, including ER stress, oxidative stress, palmitate, and chronic high glucose, decreased ER calcium levels and sarcoendoplasmic reticulum Ca(2+)-ATPase 2b expression, leading to β-cell death. Ectopic expression of mutant insulin and genetic ablation of WFS1, a causative gene for Wolfram syndrome, also decreased ER calcium levels and induced β-cell death. Hyperactivation of calpain-2, a calcium-dependent proapoptotic protease, was detected in β-cells undergoing ER calcium depletion. Ectopic expression of sarcoendoplasmic reticulum Ca(2+)-ATPase 2b, as well as pioglitazone and rapamycin treatment, could prevent calcium efflux from the ER and mitigate β-cell death under various stress conditions. Our results reveal a critical role of ER calcium depletion in β-cell death and indicate that identification of pathways and chemical compounds restoring ER calcium levels will lead to novel therapeutic modalities and pharmacological interventions for type 1 and type 2 diabetes and other ER-related diseases including Wolfram syndrome.

Phenotypical and genotypical expression of Wolfram syndrome in 12 patients from a Sicilian district where this syndrome might not be so infrequent as generally expected

BACKGROUND

Since the original description, there have been only few epidemiological studies of Wolfram syndrome (WS).

AIM

Aims of the present paper are to ascertain WS prevalence and expression in a district of North-eastern Sicily, i.e. a geographic area where consanguineous unions are not very unusual.

MATERIALS AND METHODS

Prevalence rates of WS in the Messina district were calculated by taking into consideration both the total population (653,737) and the populations included within the 0-30 year age range (202,681). We estimated the relative prevalence of WS among patients with youth-onset insulin-dependent diabetes mellitus (DM) who are currently aged under 30 years (256).

RESULTS

Global WS prevalence in our district is 1:54,478, whereas prevalence among individuals under 30 is 1:16,890 and relative prevalence among patients with juvenile-onset insulin-dependent DM is 1:22.3. When compared with the patients with insulin-dependent DM of Messina district, WS patients did not exhibit significant differences in terms of biochemical features at DM onset, whereas age at DM diagnosis was significantly earlier in WS group.

CONCLUSIONS

(a) WS prevalence is not so infrequent as generally expected; (b) in our series, DM presented before 10 years in 11/12 patients and ten cases have already developed all the four peculiar manifestations of WS by 26 years; (c) 9/12 patients exhibited a homozygous frameshift/truncation mutation (Y454_L459del_fsX454), which is the one most frequently found also in patients from other Italian regions; (d) age at DM diagnosis was significantly earlier in WS group than in the patients with insulin-dependent DM of Messina district.

Autosomal dominant diabetes arising from a Wolfram syndrome 1 mutation

We used an unbiased genome-wide approach to identify exonic variants segregating with diabetes in a multigenerational Finnish family. At least eight members of this family presented with diabetes with age of diagnosis ranging from 18 to 51 years and a pattern suggesting autosomal dominant inheritance. We sequenced the exomes of four affected members of this family and performed follow-up genotyping of additional affected and unaffected family members. We uncovered a novel nonsynonymous variant (p.Trp314Arg) in the Wolfram syndrome 1 (WFS1) gene that segregates completely with the diabetic phenotype. Multipoint parametric linkage analysis with 13 members of this family identified a single linkage signal with maximum logarithm of odds score 3.01 at 4p16.2-p16.1, corresponding to a region harboring the WFS1 locus. Functional studies demonstrate a role for this variant in endoplasmic reticulum stress, which is consistent with the β-cell failure phenotype seen in mutation carriers. This represents the first compelling report of a mutation in WFS1 associated with dominantly inherited nonsyndromic adult-onset diabetes.

Molecular characterization of WFS1 in an Iranian family with Wolfram syndrome reveals a novel frameshift mutation associated with early symptoms

Wolfram syndrome (WS) is a rare autosomal recessive neurodegenerative disorder that represents a likely source of childhood diabetes especially among countries in the consanguinity belt. The main responsible gene is WFS1 for which over one hundred mutations have been reported from different ethnic groups. The aim of this study was to identify the molecular etiology of WS and to perform a possible genotype-phenotype correlation in Iranian kindred. An Iranian family with two patients was clinically studied and WS was suspected. Genetic linkage analysis via 5 STR markers was carried out. For identification of mutations, DNA sequencing of WFS1 including all the exons, exon-intron boundaries and the promoter was performed. Linkage analysis indicated linkage to the WFS1 region. After DNA sequencing of WFS1, one novel pathogenic mutation, which causes frameshift alteration c.2177_2178insTCTTC (or c.2173_2177dupTCTTC) in exon eight, was found. The genotype-phenotype correlation analysis suggests that the presence of the homozygous mutation may be associated with early onset of disease symptoms. This study stresses the necessity of considering the molecular analysis of WFS1 in childhood diabetes with some symptoms of WS.

Phenotypic characteristics of early Wolfram syndrome

Background

Wolfram Syndrome (WFS:OMIM 222300) is an autosomal recessive, progressive, neurologic and endocrinologic degenerative disorder caused by mutations in the WFS1 gene, encoding the endoplasmic reticulum (ER) protein wolframin, thought to be involved in the regulation of ER stress. This paper reports a cross section of data from the Washington University WFS Research Clinic, a longitudinal study to collect detailed phenotypic data on a group of young subjects in preparation for studies of therapeutic interventions.

Methods

Eighteen subjects (ages 5.9–25.8, mean 14.2 years) with genetically confirmed WFS were identified through the Washington University International Wolfram Registry. Examinations included: general medical, neurologic, ophthalmologic, audiologic, vestibular, and urologic exams, cognitive testing and neuroimaging.

Results

Seventeen (94%) had diabetes mellitus with the average age of diabetes onset of 6.3 ± 3.5 years. Diabetes insipidus was diagnosed in 13 (72%) at an average age of 10.6 ± 3.3 years. Seventeen (94%) had optic disc pallor and defects in color vision, 14 (78%) had hearing loss and 13 (72%) had olfactory defects, eight (44%) had impaired vibration sensation. Enuresis was reported by four (22%) and nocturia by three (17%). Of the 11 tested for bladder emptying, five (45%) had elevated post-void residual bladder volume.

Conclusions

WFS causes multiple endocrine and neurologic deficits detectable on exam, even early in the course of the disease. Defects in olfaction have been underappreciated. The proposed mechanism of these deficits in WFS is ER stress-induced damage to neuronal and hormone-producing cells. This group of subjects with detailed clinical phenotyping provides a pool for testing proposed treatments for ER stress. Longitudinal follow-up is necessary for establishing the natural history and identifying potential biomarkers of progression.

Wolfram gene (WFS1) mutation causes autosomal dominant congenital nuclear cataract in humans

Congenital cataracts are an important cause of bilateral visual impairment in infants. Through genome-wide linkage analysis in a four-generation family of Irish descent, the disease-associated gene causing autosomal-dominant congenital nuclear cataract was mapped to chromosome 4p16.1. The maximum logarithm of odds (LOD) score was 2.62 at a recombination fraction θ=0, obtained for marker D4S432 physically close to the Wolfram gene (WFS1). By sequencing the coding regions and intron-exon boundaries of WFS1, we identified a DNA substitution (c.1385A-to-G) in exon 8, causing a missense mutation at codon 462 (E462G) of the Wolframin protein. This is the first report of a mutation in this gene causing an isolated nuclear congenital cataract. These findings suggest that the membrane trafficking protein Wolframin may be important for supporting the developing lens.