Wolfram Syndrome 1: From Genetics to Therapy

Novel WFS1 Variants in Two Moroccan Families with Wolfram Syndrome

Background: Wolfram syndrome (WFS) is an autosomal recessive disorder that often leads to diabetes, optic atrophy, and sensorineural hearing loss. The aim of this study was to determine the clinical characteristics and the genetic cause of the first two Moroccan families presenting with WFS. Methods: The clinical features of five members of two WFS families were evaluated. Whole-exome sequencing was conducted to explore the underlying genetic cause in the affected patients. Results: Two homozygous variants in the WFS1 gene were identified, each in one of the two families studied: a missense c.1329C>G variant (p.Ser443Arg) and a nonsense mutation c.1113G>A (p.Trp371Ter). These variants affected conserved amino acid residues, segregated well in the two families, and are absent from genetic databases and in controls of Moroccan origin. Bioinformatics analysis classified the two variants as pathogenic by in silico tools and molecular modeling. Conclusion: Our study identified for the first time two variants in Moroccan patients with WFS that extends the mutational spectrum associated with the disease.

Long term clinical follow up of four patients with Wolfram syndrome and urodynamic abnormalities

OBJECTIVES

Wolfram syndrome is characterised by insulin-dependent diabetes (IDDM), diabetes insipidus (DI), optic atrophy, sensorineural deafness and neurocognitive disorders. The DIDMOAD acronym has been recently modified to DIDMOAUD suggesting the rising awareness of the prevalence of urinary tract dysfunction (UD). End stage renal disease is the commonest cause of mortality in Wolfram syndrome. We present a case series with main objective of long term follow up in four children having Wolfram syndrome with evaluation of their urodynamic profile.

METHODS

A prospective follow up of four genetically proven children with Wolfram syndrome presenting to a tertiary care pediatric diabetes clinic in Pune, India was conducted. Their clinical, and urodynamic parameters were reviewed.

RESULTS

IDDM, in the first decade, was the initial presentation in all the four children (three male and one female). Three children had persistent polyuria and polydipsia despite having optimum glycemic control; hence were diagnosed to have DI and treated with desmopressin. All four patients entered spontaneous puberty. All patients had homozygous mutation in WFS1 gene; three with exon 8 and one with exon 6 novel mutations. These children with symptoms of lower urinary tract malfunction were further evaluated with urodynamic studies; two of them had hypocontractile detrusor and another had sphincter-detrusor dyssynergia. Patients with hypocontractile bladder were taught clean intermittent catheterization and the use of overnight drain.

CONCLUSIONS

We report a novel homozygous deletion in exon 6 of WFS-1 gene. The importance of evaluation of lower urinary tract malfunction is highlighted by our case series. The final bladder outcome in our cases was a poorly contractile bladder in three patients.

Optic disc drusen: Dystrophic calcification, a potential target for treatment

Optic disc drusen (ODD) are calcified, acellular bodies, seen in the optic nerve head of up to 2% of the population. Although seldomly affecting visual acuity, visual field defects are common, and severe, ischemic complications causing irreversible vision loss are known to occur. Different treatment strategies for ODD have been explored, but so far without success. This review focuses on the unique, calcified property of ODD, describing what we know about ODD pathogenesis and previously tried treatment strategies. In this context, we discuss current knowledge about calcium and pathological calcifications, including intracranial and ocular calcifications. We also explore some of the obstacles that must be addressed to develop a therapy centred on the concept of calcification, should calcification be identified as a pathogenic factor contributing to vision loss.

Dopamine D2 receptors in WFS1-neurons regulate food-seeking and avoidance behaviors

The selection and optimization of appropriate adaptive responses depends on interoceptive and exteroceptive stimuli as well as on the animal's ability to switch from one behavioral strategy to another. Although growing evidence indicate that dopamine D2R-mediated signaling events ensure the selection of the appropriate strategy for each specific situation, the underlying neural circuits through which they mediate these effects are poorly characterized. Here, we investigated the role of D2R signaling in a mesolimbic neuronal subpopulation expressing the Wolfram syndrome 1 (Wfs1) gene. This subpopulation is located within the nucleus accumbens, the central amygdala, the bed nucleus of the stria terminalis, and the tail of the striatum, all brain regions critical for the regulation of emotions and motivated behaviors. Using a mouse model carrying a temporally controlled deletion of D2R in WFS1-neurons, we demonstrate that intact D2R signaling in this neuronal population is necessary to regulate homeostasis-dependent food-seeking behaviors in both male and female mice. In addition, we found that reduced D2R signaling in WFS1-neurons impaired active avoidance learning and innate escape responses. Collectively, these findings identify a yet undocumented role for D2R signaling in WFS1-neurons as a novel effector through which dopamine optimizes appetitive behaviors and regulates defensive behaviors.

Wolfram syndrome type 1: a case series

BACKGROUND

Wolfram syndrome (WS) is a rare autosomal recessive multisystem neurodegenerative disease characterized by non-autoimmune insulin-dependent diabetes mellitus, optic atrophy, sensorineural deafness, and diabetes as the main features. Owing to clinical phenotypic heterogeneity, the misdiagnosis rate is high. However, early accurate diagnosis and comprehensive management are key to improving quality of life and prolonging life.

RESULTS

Eleven patients from seven WS pedigrees with 10 mutation sites (c.1314_1317delCTTT, c.C529T, c.C529A, c.G2105A, c.C1885T, c.1859_1860del, c.G2020A, c.C529A, c.G2105A, and c.G1393C) in the WFS1 gene were included. We conducted further expert department analysis to clarify the diagnosis and analyze the correlation between genes and phenotypes.

CONCLUSIONS

The genotypes of these patients were closely associated with their phenotypes. The clinical data of the patients were analyzed to provide a basis for the diagnosis and clinical management of the disease.

Wolfram Syndrome: A Curious Case of Repetitive Loss of Consciousness

Wolfram syndrome is a rare, multisystemic, progressive, and autosomal-recessive genetic disease, characterized by diabetes mellitus and diabetes insipidus, optic nerve atrophy, deafness, and other neurological signs. The diagnosis is usually based on history and clinical manifestations but genetic tests are necessary for confirmation. Currently, there are no treatments available to cure or delay disease progression. This report describes a case of a 23-year-old male diagnosed with Wolfram syndrome who presented to the emergency department with several episodes of loss of consciousness. This case reinforces the need for an early diagnosis of obstructive and central apneas, respiratory failure, and dysphagia, in order to prevent and treat the complications of this disease and to improve patients' quality of life.

Neuro-Ophthalmologic Variability in Presentation of Genetically Confirmed Wolfram Syndrome: A Case Series and Review

Wolfram syndrome is a neurodegenerative disorder caused by pathogenic variants in the genes WFS1 or CISD2. Clinically, the classic phenotype is composed of optic atrophy, diabetes mellitus type 1, diabetes insipidus, and deafness. Wolfram syndrome, however, is phenotypically heterogenous with variable clinical manifestations and age of onset. We describe four cases of genetically confirmed Wolfram syndrome with variable presentations, including acute-on-chronic vision loss, dyschromatopsia, and tonic pupils. All patients had optic atrophy, only three had diabetes, and none exhibited the classic Wolfram phenotype. MRI revealed a varying degree of the classical features associated with the syndrome, including optic nerve, cerebellar, and brainstem atrophy. The cohort's genotype and presentation supported the reported phenotype-genotype correlations for Wolfram, where missense variants lead to milder, later-onset presentation of the Wolfram syndrome spectrum. When early onset optic atrophy and/or diabetes mellitus are present in a patient, a diagnosis of Wolfram syndrome should be considered, as early diagnosis is crucial for the appropriate referrals and management of the associated conditions. Nevertheless, the condition should also be considered in otherwise unexplained, later-onset optic atrophy, given the phenotypic spectrum.

Wolfram Syndrome 1 in Two Brothers Treated with Insulin Pump

Background/Objective

Wolfram syndrome (WS) is a rare genetic disorder, in which patients develop early-onset diabetes mellitus (DM), optic nerve atrophy, and neurodegeneration, which has no specific treatment available. Here, we report 2 brothers treated with an insulin pump to manage the alterations of the glycemic levels due to the DM.

Case Report

We present the case of 2 siblings diagnosed with Wolfram syndrome 1, they presented with typical endocrinological and neurodegenerative early manifestations, one brother was treated with a sensor-augmented insulin infusion system, and the other with an insulin pump. Both reached a better metabolic state and had improved quality of life.

Discussion

The management of WS is still a challenge; however, the use of a sensor-augmented insulin infusion system and the information that it provides may offer better care to patients who require frequent monitoring and adjustments in their treatment. It has been reported that the neurodegenerative progression of WS is also associated with high glucose peaks; therefore, it is necessary to control it, even when it is hard due to the difficult-to-manage DM. There is only 1 previous case report of WS with insulin pump that describes the benefits of continuous subcutaneous insulin infusion and tight metabolic control during pregnancy.

Conclusion

The use of insulin pumps may be an effective treatment for DM in WS patients, mainly in terms of improving the prognosis of difficult-to-manage DM.

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.

Wfs1E864K knock-in mice illuminate the fundamental role of Wfs1 in endocochlear potential production

Wolfram syndrome (WS) is a rare neurodegenerative disorder encompassing diabetes mellitus, diabetes insipidus, optic atrophy, hearing loss (HL) as well as neurological disorders. None of the animal models of the pathology are presenting with an early onset HL, impeding the understanding of the role of Wolframin (WFS1), the protein responsible for WS, in the auditory pathway. We generated a knock-in mouse, the Wfs1E864K line, presenting a human mutation leading to severe deafness in affected individuals. The homozygous mice showed a profound post-natal HL and vestibular syndrome, a collapse of the endocochlear potential (EP) and a devastating alteration of the stria vascularis and neurosensory epithelium. The mutant protein prevented the localization to the cell surface of the Na+/K+ATPase β1 subunit, a key protein for the maintenance of the EP. Overall, our data support a key role of WFS1 in the maintenance of the EP and the stria vascularis, via its binding partner, the Na+/K+ATPase β1 subunit.

Paediatric Wolfram syndrome Type 1: should gonadal dysfunction be part of the diagnostic criteria?

Aims

Wolfram Syndrome Spectrum Disorder (WFS1-SD), in its "classic" form, is a rare autosomal recessive disease with poor prognosis and wide phenotypic spectrum. Insulin dependent diabetes mellitus (DM), optic atrophy (OA) diabetes insipidus (DI) and sensorineural deafness (D) are the main features of WFS1-SD. Gonadal dysfunction (GD) has been described mainly in adults with variable prevalence and referred to as a minor clinical feature. This is the first case series investigating gonadal function in a small cohort of paediatric patients affected by WFS1-SD.

Methods

Gonadal function was investigated in eight patients (3 male and 5 female) between 3 and 16 years of age. Seven patients have been diagnosed with classic WFS1-SD and one with non-classic WFS1-SD. Gonadotropin and sex hormone levels were monitored, as well as markers of gonadal reserve (inhibin-B and anti-Mullerian hormone). Pubertal progression was assessed according to Tanner staging.

Results

Primary hypogonadism was diagnosed in 50% of patients (n=4), more specifically 67% (n=2) of males and 40% of females (n=2). Pubertal delay was observed in one female patient. These data confirm that gonadal dysfunction may be a frequent and underdiagnosed clinical feature in WFS1-SD.

Conclusions

GD may represent a frequent and earlier than previously described feature in WFS1-SD with repercussions on morbidity and quality of life. Consequently, we suggest that GD should be included amongst clinical diagnostic criteria for WFS1-SD, as has already been proposed for urinary dysfunction. Considering the heterogeneous and elusive presentation of WFS1-SD, this clinical feature may assist in an earlier diagnosis and timely follow-up and care of treatable associated diseases (i.e. insulin and sex hormone replacement) in these young patients.

GLP-1 receptor agonists as promising disease-modifying agents in WFS1 spectrum disorder

WFS1 spectrum disorder (WFS1-SD) is a rare monogenic neurodegenerative disorder whose cardinal symptoms are childhood-onset diabetes mellitus, optic atrophy, deafness, diabetes insipidus, and neurological signs ranging from mild to severe. The prognosis is poor as most patients die prematurely with severe neurological disabilities such as bulbar dysfunction and organic brain syndrome. Mutation of the WFS1 gene is recognized as the prime mover of the disease and responsible for a dysregulated ER stress signaling, which leads to neuron and pancreatic β-cell death. There is no currently cure and no treatment that definitively arrests the progression of the disease. GLP-1 receptor agonists appear to be an efficient way to reduce elevated ER stress in vitro and in vivo, and increasing findings suggest they could be effective in delaying the progression of WFS1-SD. Here, we summarize the characteristics of GLP-1 receptor agonists and preclinical and clinical data obtained by testing them in WFS1-SD as a feasible strategy for managing this disease.

Chronic Stress Alters Hippocampal Renin-Angiotensin-Aldosterone System Component Expression in an Aged Rat Model of Wolfram Syndrome

Biallelic mutations in the gene encoding WFS1 underlie the development of Wolfram syndrome (WS), a rare neurodegenerative disorder with no available cure. We have previously shown that Wfs1 deficiency can impair the functioning of the renin-angiotensin-aldosterone system (RAAS). The expression of two key receptors, angiotensin II receptor type 2 (Agtr2) and bradykinin receptor B1 (Bdkrb1), was downregulated both in vitro and in vivo across multiple organs in a rat model of WS. Here, we show that the expression of key RAAS components is also dysregulated in neural tissue from aged WS rats and that these alterations are not normalized by pharmacological treatments (liraglutide (LIR), 7,8-dihydroxyflavone (7,8-DHF) or their combination). We found that the expression of angiotensin II receptor type 1a (Agtr1a), angiotensin II receptor type 1b (Agtr1b), Agtr2 and Bdkrb1 was significantly downregulated in the hippocampus of WS animals that experienced chronic experimental stress. Treatment-naïve WS rats displayed different gene expression patterns, underscoring the effect of prolonged experiment-induced stress. Altogether, we posit that Wfs1 deficiency disturbs RAAS functioning under chronic stressful conditions, thereby exacerbating neurodegeneration in WS.

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.

A Pair of Siblings With Wolfram Syndrome: A Review of the Literature and Treatment Options

Wolfram syndrome (WS) is a rare genetic disorder typically characterized by juvenile onset diabetes mellitus, optic atrophy, hearing loss, diabetes insipidus, and neurodegeneration. There would be a high index of clinical suspicion for WS when clinical manifestations of type 1 diabetes and optic atrophy present together. Genetic analysis is often required to confirm the diagnosis. We describe a pair of Chinese siblings diagnosed with WS at ages 20 and 24 years, respectively. DNA sequencing of the WFS1 gene which encodes for Wolframin ER Transmembrane Glycoprotein identified a heterozygous nonsense variant NM_006005.3: c.1999C>T p.(Gln667*) and a heterozygous missense variant c.2170C>T p.(Pro724Ser) in exon 8 of the gene for both siblings. There is no curative treatment for WS and management of this debilitating disease is aimed at treating individual clinical manifestations, slowing disease progression, and improving quality of life. Treatment with liraglutide, a glucagon-like-peptide-1 receptor agonist, and tauroursodeoxycholic acid was started for the younger sibling, the proband. There was reduction in insulin requirements and improvement in glycemic control. The other sibling was not offered liraglutide due to her complex treatment regimen for end-organ failure. Genetic testing is a valuable tool to detect WS early to allow precise and prompt diagnosis, thereby facilitating the coordinated care from a multidisciplinary team of clinicians.

Mutation analysis of the WFS1 gene in a Chinese family with autosomal-dominant non-syndrome deafness

To analyse the pathogenic genes and mutations of a family with hereditary deafness. We recruited a three-generation family with NSHL. A detailed medical history inquiry and related examinations were performed. Next-generation sequencing (NGS) was used to confirm the gene mutation in the proband, and Sanger sequencing was used for verification. The effect of the WFS1 mutation on the function and structure of the wolframin protein was predicted by multiple computational software. From the Gene Expression Omnibus (GEO) database, we obtained GSE40585 dataset and performed enrichment analyses. The family clinically manifested as autosomal dominant NSHL. A novel WFS1 c.2421C>G (p.Ser807Arg) mutation was identified in four affected individuals in the pedigree . The p.Ser807Arg mutation is a highly conserved residue and causes an increase in protein stability. It had an important influence on not only amino acid size, charge and hydrophobicity but also protein intermolecular hydrogen bonding and spatial structure. There were differentially expressed genes (DEGs) in GSE40585 dataset. Enrichment analysis revealed that DEGs mainly functioned in amino acid metabolism, signal transduction and dephosphorylation. We reported a novel mutation c.2421C>G (p.Ser807Arg in WFS1. This study expands the mutation spectrum of WFS1.

A Novel Missense WFS1 Variant: Expanding the Mutational Spectrum Associated with Nonsyndromic Low-Frequency Sensorineural Hearing Loss

Background. Nonsyndromic low-frequency sensorineural hearing loss (LFSNHL) is an uncommon form of hearing loss (HL) that typically affects frequencies at 2000 Hz and below. Heterozygous variants in the WFS1 gene at the DFNA6/14/38 locus are considered a common cause of LFSNHL. To date, 34 different pathogenic genetic variants have been reported to cause LFSNHL with seven of these variants identified in the Chinese population. However, limited reports are available on the association between WFS1 gene and LFSNHL. Here, we report a five-generation Chinese family with an autosomal dominant inheritance pattern of postlingual and progressive LFSNHL. Methods. Routine clinical and audiological examinations were performed on 16 affected and 7 healthy members in this family. The targeted next-generation sequencing of 127 known deafness genes was performed to identify variants in affected individuals. Sanger sequencing were further employed to confirm the pathogenic variant identified. Results. A novel heterozygous pathogenic genetic variant c.2530G > T (p.Ala844Ser) was identified in the WFS1 gene in all patients of this family. The mutated Ala residue is evolutionarily conserved and cosegregated with HL. The variant was predicted to be deleterious by MutationTaster, PolyPhen-2, LRT, and Fathmm software. Conservation analysis and 3D protein structure model indicated that the variant caused a structural change in the protein. Conclusions. Our present study identifies a novel heterozygous WFS1 variant associated with LFSNHL in a Chinese family.

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.

β-cyclodextrin based nano gene delivery using pharmaceutical applications to treat Wolfram syndrome

Wolfram syndrome is a rare multisystem autosomal recessive neurodegenerative disorder that affects the brain and central nervous system. Currently, there is no cure or treatment for Wolfram syndrome. Therefore, new techniques are needed to target the loss of the WFS1 gene. Gene therapy approach to introduce a functional gene using a viral or a non-viral vector could be a treatment strategy for Wolfram syndrome 1 (WS1). Viral vectors have therapeutic benefits and greater efficiency; however, they pose a high health risk. Recently pharmaceutical therapeutic research has developed cell-penetrating non-viral nano molecules that could be used as vectors for gene delivery. Among nonviral vectors, the unique properties of β-cyclodextrin suggest that it can be a promising safe vector for gene delivery.