Audiologic and vestibular findings in Wolfram syndrome

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.

Plasma Neurofilament Light Chain Levels Are Elevated in Children and Young Adults With Wolfram Syndrome

Wolfram syndrome is a rare disease caused by pathogenic variants in the WFS1 gene with progressive neurodegeneration. As an easily accessible biomarker of progression of neurodegeneration has not yet been found, accurate tracking of the neurodegenerative process over time requires assessment by costly and time-consuming clinical measures and brain magnetic resonance imaging (MRI). A blood-based measure of neurodegeneration, neurofilament light chain (NfL), is relatively inexpensive and can be repeatedly measured at remote sites, standardized, and measured in individuals with MRI contraindications. To determine whether NfL levels may be of use in disease monitoring and reflect disease activity in Wolfram syndrome, plasma NfL levels were compared between children and young adults with Wolfram syndrome (n = 38) and controls composed of their siblings and parents (n = 35) and related to clinical severity and selected brain region volumes within the Wolfram group. NfL levels were higher in the Wolfram group [median (interquartile range) NfL = 11.3 (7.8-13.9) pg/mL] relative to controls [5.6 (4.5-7.4) pg/mL]. Within the Wolfram group, higher NfL levels related to worse visual acuity, color vision and smell identification, smaller brainstem and thalamic volumes, and faster annual rate of decrease in thalamic volume over time. Our findings suggest that plasma NfL levels can be a powerful tool to non-invasively assess underlying neurodegenerative processes in children, adolescents and young adults with Wolfram syndrome.

Clinical Peculiarities in a Cohort of Patients with Wolfram Syndrome 1

Wolfram syndrome 1 is a rare, autosomal recessive, neurodegenerative, progressive disorder. Insulin-dependent, non-autoimmune diabetes mellitus and bilateral progressive optic atrophy are both sensitive and specific criteria for clinical diagnosis. The leading cause of death is central respiratory failure resulting from brainstem atrophy. We describe the clinical features of fourteen patients from seven different families followed in our Diabetes Center. The mean age at Wolfram syndrome 1 diagnosis was 12.4 years. Diabetes mellitus was the first clinical manifestation, in all patients. Sensorineural hearing impairment and central diabetes insipidus were present in 85.7% of patients. Other endocrine findings included hypogonadotropic hypogonadism (7.1%), hypergonadotropic hypogonadism (7.1%), and Hashimoto’s thyroiditis (21.4%). Neuropsychiatric disorders were detected in 35.7% of patients, and urogenital tract abnormalities were present in 21.4%. Finally, heart diseases were found in 14.2% of patients. Eight patients (57.1%) died at the mean age of 27.3 years. The most common cause of death was respiratory failure which occurred in six patients. The remaining two died due to end-stage renal failure and myocardial infarction. Our data are superimposable with those reported in the literature in terms of mean age of onset, the clinical course of the disease, and causes of death. The frequency of deafness and diabetes insipidus was higher in our patients. The incidence of urogenital diseases was lower although it led to the death of one patient. Long-term follow-up studies including large patient cohorts are necessary to establish potential genotype-phenotype correlation in order to personalize the most suitable clinical approach for each patient.

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.

Genetics Influences Drug Consumption in Medication Overuse Headache, Not in Migraine: Evidence From Wolframin His611Arg Polymorphism Analysis

Background: The Wolframin His611Arg polymorphism can influence drug consumption in psychiatric patients with impulsive addictive behavior. This cross-sectional study aims to assess the prevalence of the Wolframin His611Arg polymorphism in MOH, a secondary headache belonging to the spectrum of addictive disorders, episodic migraine (EM), and healthy subjects (HS), and its influence on drug consumption.

Methods: One-hundred and seventy-two EM, 107 MOH, and 83 HS were enrolled and genotyped for the Wolframin His611Arg polymorphism. Subjects were classified as homozygous for allele His (H/H subjects), homozygous for allele Arg (R/R subjects), and heterozygous (H/R subjects), regrouped as R/R and carriers of allele H (non-R/R), and matched for clinical data.

Results: There were no differences in allelic distributions between the three groups (p = 0.19). Drug consumption and other clinical characteristics were not influenced by the Wolframin His611Arg polymorphism (p = 0.42; β = 0.04) in the EM group. Among the MOH population, R/R subjects consumed more analgesics (p < 0.0001; β = −0.38), particularly combination drugs (p = 0.0001; d = 2.32).

Discussion: The Wolframin His611Arg polymorphism has a similar prevalence between the MOH, EM, and HS groups. The presence of the R/R genotype does not influence symptomatic drug consumption in EM, whereas it determines an increased use of symptomatic drugs in the MOH group, in particular combination drugs (i.e., drugs containing psychoactive compounds).

Conclusions: Our findings are consistent with the hypothesis that the Wolframin His611Arg polymorphism plays its effect only in the MOH population, influencing the impulsivity control underlying addictive behavior.

A cost of illness study evaluating the burden of Wolfram syndrome in the United Kingdom

Background

Wolfram syndrome is a rare genetic, progressive, neurodegenerative disorder characterised by childhood-onset diabetes mellitus, diabetes insipidus, optic atrophy and deafness. To date, the economic burden of Wolfram syndrome has not been well-studied or reported. The aim of this study was to evaluate the cost of illness (COI) of all people with Wolfram syndrome in the UK and to identify major determinants of cost from a service provider perspective (National Health Service, NHS).

Methods

A prevalence-based approach was used to model the UK Wolfram syndrome specialist service. Model inputs were informed by a pragmatic literature review and UK reference costs, in conjunction with patient interviews and expert opinion. A deterministic sensitivity analysis (DSA) was run at 10% to identify major cost drivers.

Results

The total COI of all people with Wolfram syndrome to the NHS was £1,055,899 per year, with an average annual cost per person with Wolfram syndrome of £16,498. Costs associated with diabetes mellitus care, late-stage diabetes mellitus complications and hearing impairment contributed most to the COI (18.9, 21.4 and 15.8% of the COI, respectively). The DSA identified costs associated with hearing impairment, diabetes mellitus care and end-stage renal disease (a diabetes mellitus complication) as major model drivers.

Conclusions

The annual cost of Wolfram syndrome to the NHS was found to be substantial, with areas of potential cost savings identified, such as diabetes mellitus management. This model provides crucial information to facilitate economic evaluation of prospective therapies for this disease.

Evidence for altered neurodevelopment and neurodegeneration in Wolfram syndrome using longitudinal morphometry

Wolfram syndrome is a rare disease caused by mutations in the WFS1 gene leading to symptoms in early to mid-childhood. Brain structural abnormalities are present even in young children, but it is not known when these abnormalities arise. Such information is critical in determining optimal outcome measures for clinical trials and in understanding the aberrant neurobiological processes in Wolfram syndrome. Using voxel-wise and regional longitudinal analyses, we compared brain volumes in Wolfram patients (n = 29; ages 5–25 at baseline; mean follow-up = 3.6 years), to age and sex-equivalent controls (n = 52; ages 6–26 at baseline; mean follow-up = 2.0 years). Between groups, white and gray matter volumes were affected differentially during development. Controls had uniformly increasing volume in white matter, whereas the Wolfram group had stable (optic radiations) or decreasing (brainstem, ventral pons) white matter volumes. In gray matter, controls had stable (thalamus, cerebellar cortex) or decreasing volumes (cortex), whereas the Wolfram group had decreased volume in thalamus and cerebellar cortex. These patterns suggest that there may be early, stalled white matter development in Wolfram syndrome, with additional degenerative processes in both white and gray matter. Ideally, animal models could be used to identify the underlying mechanisms and develop specific interventions.

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.

Neuroimaging evidence of deficient axon myelination in Wolfram syndrome

Wolfram syndrome is a rare autosomal recessive genetic disease characterized by insulin dependent diabetes and vision, hearing and brain abnormalities which generally emerge in childhood. Mutations in the WFS1 gene predispose cells to endoplasmic reticulum stress-mediated apoptosis and may induce myelin degradation in neuronal cell models. However, in vivo evidence of this phenomenon in humans is lacking. White matter microstructure and regional volumes were measured using magnetic resonance imaging in children and young adults with Wolfram syndrome (n = 21) and healthy and diabetic controls (n = 50). Wolfram patients had lower fractional anisotropy and higher radial diffusivity in major white matter tracts and lower volume in the basilar (ventral) pons, cerebellar white matter and visual cortex. Correlations were found between key brain findings and overall neurological symptoms. This pattern of findings suggests that reduction in myelin is a primary neuropathological feature of Wolfram syndrome. Endoplasmic reticulum stress-related dysfunction in Wolfram syndrome may interact with the development of myelin or promote degeneration of myelin during the progression of the disease. These measures may provide objective indices of Wolfram syndrome pathophysiology that will be useful in unraveling the underlying mechanisms and in testing the impact of treatments on the brain.

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.

Ophthalmologic correlates of disease severity in children and adolescents with Wolfram syndrome

PURPOSE

To describe an ophthalmic phenotype in children at relatively early stages of Wolfram syndrome.

METHODS

Quantitative ophthalmic testing of visual acuity, color vision, automated visual field sensitivity, optic nerve pallor and cupping, and retinal nerve fiber layer (RNFL) thickness assessed by optical coherence tomography (OCT) was performed in 18 subjects 5-25 years of age. Subjects were also examined for presence or absence of afferent pupillary defects, cataracts, nystagmus, and strabismus.

RESULTS

Subnormal visual acuity was detected in 89% of subjects, color vision deficits in 94%, visual field defects in 100%, optic disk pallor in 94%, abnormally large optic nerve cup:disk ratio in 33%, thinned RNFL in 100%, afferent pupillary defects in 61%, cataracts in 22%, nystagmus in 39%, and strabismus in 39% of subjects. RNFL thinning (P < 0.001), afferent pupillary defects (P = 0.01), strabismus (P = 0.04), and nystagmus (P = 0.04) were associated with more severe disease using the Wolfram United Rating Scale.

CONCLUSIONS

Children and adolescents with Wolfram syndrome have multiple ophthalmic markers that correlate with overall disease severity. RNFL thickness measured by OCT may be the most reliable early marker.