Reliability and validity of the Wolfram Unified Rating Scale (WURS)

Genotype and clinical characteristics of patients with Wolfram syndrome and WFS1-related disorders

Objective: Wolfram syndrome (WFS) is an autosomal recessive disorder associated with juvenile-onset diabetes mellitus, optic atrophy, diabetes insipidus, and sensorineural hearing loss. We sought to elucidate the relationship between genotypic and phenotypic presentations of Wolfram syndrome which would assist clinicians in classifying the severity and prognosis of Wolfram syndrome more accurately. Approach: Patient data from the Washington University International Registry and Clinical Study for Wolfram Syndrome and patient case reports were analyzed to select for patients with two recessive mutations in the WFS1 gene. Mutations were classified as being either nonsense/frameshift variants or missense/in-frame insertion/deletion variants. Missense/in-frame variants were further classified as transmembrane or non-transmembrane based on whether they affected amino acid residues predicted to be in transmembrane domains of WFS1. Statistical analysis was performed using Wilcoxon rank-sum tests with multiple test adjustment applied via the Bonferonni correction. Results: A greater number of genotype variants correlated with earlier onset and a more severe presentation of Wolfram syndrome. Secondly, non-sense and frameshift variants had more severe phenotypic presentations than missense variants, as evidenced by diabetes mellitus and optic atrophy emerging significantly earlier in patients with two nonsense/frameshift variants compared with zero or one nonsense/frameshift variants. In addition, the number of transmembrane in-frame variants demonstrated a statistically significant dose-effect on age of onset of diabetes mellitus and optic atrophy among patients with either one or two in-frame variants. Summary/Conclusion: The results contribute to our current understanding of the genotype-phenotype relationship of Wolfram syndrome, suggesting that alterations in coding sequences result in significant changes in the presentation and severity of Wolfram. The impact of these findings is significant, as the results will aid clinicians in predicting more accurate prognoses and pave the way for personalized treatments for Wolfram syndrome.

Genotype and Clinical Characteristics of Patients with Wolfram Syndrome and WFS1-related Disorders

Objective

Wolfram syndrome (WFS) is an autosomal recessive disorder associated with juvenile-onset diabetes mellitus, optic atrophy, diabetes insipidus, and sensorineural hearing loss. We sought to elucidate the relationship between genotypic and phenotypic presentations of Wolfram syndrome which would assist clinicians in classifying the severity and prognosis of Wolfram syndrome more accurately.

Approach

Patient data from the Washington University International Registry and Clinical Study for Wolfram Syndrome and patient case reports were analyzed to select for patients with two recessive mutations in the WFS1 gene. Mutations were classified as being either nonsense/frameshift variants or missense/in-frame insertion/deletion variants and statistical analysis was performed using unpaired and paired t-tests and one- and two-way ANOVA with Tukey's or Dunnett's tests.

Results

A greater number of genotype variants correlated with earlier onset and a more severe presentation of Wolfram syndrome. Secondly, non-sense and frameshift variants had more severe phenotypic presentations than missense variants, as evidenced by optic atrophy emerging significantly earlier in patients with 2 nonsense/frameshift alleles compared with 0 missense transmembrane variants. In addition, the number of transmembrane in-frame variants demonstrated a statistically significant dose-effect on age of onset of diabetes mellitus and optic atrophy.

Summary / Conclusions

The results contribute to our current understanding of the genotype-phenotype relationship of Wolfram syndrome, suggesting that alterations in coding sequences result in significant changes in the presentation and severity of Wolfram. The impact of these findings is significant, as the results will aid clinicians in predicting more accurate prognoses and pave the way for personalized treatments for Wolfram syndrome.

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.

Longitudinal progression of diabetes mellitus in Wolfram syndrome: The Washington University Wolfram Research Clinic experience

OBJECTIVE

(1) Describe the progression of diabetes mellitus over time in an observational study of Wolfram syndrome, a rare, genetic, neurodegenerative disorder, which often includes diabetes mellitus and is typically diagnosed during childhood or adolescence. (2) Determine whether C-peptide could be used as a marker of diabetes progression in interventional trials for Wolfram syndrome.

METHODS

N = 44 (25F/19M) participants with genetically confirmed Wolfram syndrome attended the Washington University Wolfram Research Clinic annually from 2010 to 2019. Medical history, physical examinations, blood sampling, and questionnaires were used to collect data about diabetes mellitus and other components of Wolfram syndrome. Beta-cell function was assessed by determination of C-peptide during a mixed meal tolerance test. Random coefficients models evaluated the rate of progression of C-peptide over time, and power analyses were used to estimate the number of subjects needed to detect a change in C-peptide decline during an intervention trial.

RESULTS

93.2% of patients had diabetes mellitus. Mean HbA1c across all study visits was 7.9%. C-peptide significantly decreased with increasing duration of diabetes mellitus (p < 0.0001); an optimal break point in C-peptide decline was identified to occur between 0.1 and 2.3 years after diabetes mellitus diagnosis. Twenty patients per group (active vs. control) were estimated to be needed to detect a 60% slowing of C-peptide decline during the first 2.3 years following diabetes diagnosis.

CONCLUSION

C-peptide declines over time in Wolfram syndrome and could potentially be used as a marker of diabetes progression in interventional studies for Wolfram syndrome, especially within the first 2 years after diabetes diagnosis.

Urinary Tract Involvement in Wolfram Syndrome: A Narrative Review

Wolfram Syndrome (WS) is a rare neurodegenerative disease with autosomal recessive inheritance and characterized by juvenile onset, non-autoimmune diabetes mellitus and later followed by optic atrophy leading to blindness, diabetes insipidus, hearing loss, and other neurological and endocrine dysfunctions. A wide spectrum of neurodegenerative abnormalities affecting the central nervous system has been described. Among these complications, neurogenic bladder and urodynamic abnormalities also deserve attention. Urinary tract dysfunctions (UTD) up to end stage renal disease are a life-threatening complication of WS patients. Notably, end stage renal disease is reported as one of the most common causes of death among WS patients. UTD have been also reported in affected adolescents. Involvement of the urinary tract occurs in about 90% of affected patients, at a median age of 20 years and with peaks at 13, 21 and 33 years. The aim of our narrative review was to provide an overview of the most important papers regarding urological impairment in Wolfram Syndrome. A comprehensive search on PubMed including Wolfram Syndrome and one or more of the following terms: chronic renal failure, bladder dysfunction, urological aspects, and urinary tract dysfunction, was done. The exclusion criteria were studies not written in English and not including urinary tract dysfunction deep evaluation and description. Studies mentioning general urologic abnormalities without deep description and/or follow-up were not considered. Due to the rarity of the condition, we considered not only papers including pediatric patients, but also papers with pediatric and adult case reports

Content Validation of Clinician-Reported Items for a Severity Measure for CDKL5 Deficiency Disorder

CDKL5 deficiency disorder (CDD) results in early-onset seizures and severe developmental impairments. A CDD clinical severity assessment (CCSA) was previously developed with clinician and parent-report items to capture information on a range of domains. Consistent with US Food and Drug Administration (FDA) guidelines, content validation is the first step in evaluating the psychometric properties of an outcome measure. The aim of this study was to validate the content of the clinician-reported items in the CCSA (CCSA-Clinician). Eight neurologists leading the USA CDD Center of Excellence clinics were interviewed using the "think aloud" technique to critique 26 clinician-reported items. Common themes were aggregated, and a literature search of related assessments informed item modifications. The clinicians then participated in 2 consensus meetings to review themes and finalize the items. A consensus was achieved for the content of the CCSA-Clinician. Eight of the original items were omitted, 11 items were added, and the remaining 18 items were revised. The final 29 items were classified into 2 domains: functioning and neurologic impairments. This study enabled refinement of the CCSA-Clinician and provided evidence for its content validity. This preliminary validation is essential before field testing and further validation, in order to advance the instrument toward clinical trial readiness.

Sleep disturbances in Wolfram syndrome

Background

Wolfram syndrome is a rare disorder associated with diabetes mellitus, diabetes insipidus, optic nerve atrophy, hearing and vision loss, and neurodegeneration. Sleep complaints are common but have not been studied with objective measures. Our goal was to assess rates of sleep apnea and objective and self-reported measures of sleep quality, and to determine the relationship of sleep pathology to other clinical variables in Wolfram syndrome patients.

Methods

Genetically confirmed Wolfram syndrome patients were evaluated at the 2015 and 2016 Washington University Wolfram Syndrome Research Clinics. Patients wore an actigraphy device and a type III ambulatory sleep study device and completed the Epworth Sleepiness Scale (ESS), the Pittsburgh Sleep Quality Index (PSQI) and/or the Pediatric Sleep Questionnaire (PSQ). PSQI and PSQ questionnaire data were compared to a previously collected group of controls. Patients were characterized clinically with the Wolfram Unified Rating Scale (WURS) and a subset underwent magnetic resonance imaging (MRI) for brain volume measurements.

Results

Twenty-one patients were evaluated ranging from age 8.9–29.7 years. Five of 17 (29%) adult patients fit the criteria for obstructive sleep apnea (OSA; apnea-hypopnea index [AHI] ≥ 5) and all 4 of 4 (100%) children aged 12 years or younger fit the criteria for obstructive sleep apnea (AHI’s ≥ 1). Higher AHI was related to greater disease severity (higher WURS Physical scores). Higher mixed apnea scores were related to lower brainstem and cerebellar volumes. Patients’ scores on the PSQ were higher than those of controls, indicating greater severity of childhood obstructive sleep-related breathing disorders.

Conclusions

Wolfram syndrome patients had a high rate of OSA. Further study would be needed to assess how these symptoms change over time. Addressing sleep disorders in Wolfram syndrome patients would likely improve their overall health and quality of life.

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.

Pancreatic stone protein/regenerating protein is a potential biomarker for endoplasmic reticulum stress in beta cells

Endoplasmic reticulum (ER) stress in beta cells is an important pathogenic component of both type 1 and type 2 diabetes mellitus, as well as genetic forms of diabetes, especially Wolfram syndrome. However, there are currently no convenient ways to assess ER stress in beta cells, raising the need for circulating ER stress markers indicative of beta cell health. Here we show that pancreatic stone protein/regenerating protein (PSP/reg) is a potential biomarker for ER stressed beta cells. PSP/reg levels are elevated in cell culture and mouse models of Wolfram syndrome, a prototype of ER stress-induced diabetes. Moreover, PSP/reg expression is induced by the canonical chemical inducers of ER stress, tunicamycin and thapsigargin. Circulating PSP/reg levels are also increased in some patients with Wolfram syndrome. Our results therefore reveal PSP/reg as a potential biomarker for beta cells under chronic ER stress, as is the case in Wolfram syndrome.

Understanding activity participation among individuals with Wolfram Syndrome

INTRODUCTION

Wolfram Syndrome (WFS) is a rare genetic disease associated with a variety of progressive metabolic and neurologic impairments. Previous research has focused on WFS-related impairments and biomarkers for disease progression; however, information about how WFS impacts participation in daily activities is lacking.

METHODS

WFS (n=45; 20 children, 25 adults) participants completed an online questionnaire about activity participation. Thirty-six non-WFS comparison participants (11 children; 25 adults) completed a portion of the questionnaire. Symptom data from a subset of WFS participants (n=20) were also examined in relation to participation data.

RESULTS

WFS children and adults had lower participation than non-WFS children and adults in almost all activity domains, and social and exercise-related activities were the most problematic. In the subset of WFS adults with symptom data, poorer vision, balance, gait, hearing, and overall symptom severity related to lower participation.

CONCLUSIONS

WFS appears to negatively impact participation in a variety of activities, and this effect may increase as people age and/or WFS progresses. The most functionally-pertinent WFS symptoms are those associated with neurodegeneration especially vision loss and walking and balance problems. This study revealed symptoms and activity domains that are most relevant for people with WFS and, thus, can inform current practice and treatment development research.

Visual pathway function and structure in Wolfram syndrome: patient age, variation and progression

Background/aims

To report alterations in visual acuity and visual pathway structure over an interval of 1–3 years in a cohort of children, adolescents and young adults who have Wolfram syndrome (WFS) and to describe the range of disease severity evident in patients with WFS whose ages differed by as much as 20 years at first examination.

Methods

Annual, prospective ophthalmological examinations were performed in conjunction with retinal nerve fibre layer (RNFL) analysis. Diffusion tensor MRI-derived fractional anisotropy was used to assess the microstructural integrity of the optic radiations (OR FA).

Results

Mean age of the 23 patients with WFS in the study was 13.8 years (range 5–25 years). Mean log minimum angle resolution visual acuity was 0.66 (20/91). RNFL thickness was subnormal in even the youngest patients with WFS. Average RNFL thickness in patients with WFS was 57±8 µ or ~40% thinner than that measured in normal (94±10 µ) children and adolescents (P<0.01). Lower OR FA correlated with worse visual acuity (P=0.006). Subsequent examinations showed declines (P<0.05) in visual acuity, RNFL thickness and OR FA at follow-up intervals of 12–36 months. However, a wide range of disease severity was evident across ages: some of the youngest patients at their first examination had deficits more severe than the oldest patients.

Conclusion

The genetic mutation of WFS causes damage to both pregeniculate and postgeniculate regions of the visual pathway. The damage is progressive. The decline in visual pathway structure is accompanied by declines of visual function. Disease severity differs widely in individual patients and cannot be predicted from their age.

The effects of disease-related symptoms on daily function in Wolfram Syndrome

OBJECTIVE:

To investigate daily function among individuals with Wolfram Syndrome (WFS) and examine whether any limitations are related to disease-related symptoms.

METHODS:

WFS (n = 31), Type 1 diabetic (T1DM; n = 25), and healthy control (HC; n = 29) participants completed the Pediatric Quality of Life Questionnaire (PEDSQL) Self and Parent Report. PEDSQL domain scores were compared among these groups and between WFS patients with and without specific disease-related symptoms. Relationships between PEDSQL scores and symptom severity as assessed by the Wolfram Unified Rating Scale (WURS) Physical Scale were also examined.

RESULTS:

Across most domains, the WFS group had lower PEDSQL Self and Parent Report scores than the T1DM and HC groups. WFS participants with urinary, sleep, and temperature regulation problems had lower PEDSQL scores than those without. The WURS Physical Scale correlated with Self and Parent Report PEDSQL domains. WFS group Self and Parent Reports correlated with each other.

CONCLUSIONS:

The WFS group reported lower daily function compared to T1DM and HC groups. Within WFS, worse symptom severity and the specific symptoms of sleep, temperature regulation, and urinary problems were associated with poorer daily function. These findings provide rationale for an increased emphasis on identifying, treating and understanding these less well-known symptoms of WFS.

Developing a patient satisfaction questionnaire for services provided in Iranian community pharmacies

Objective:

To develop a valid and reliable instrument in the Persian language for evaluating patient satisfaction with services provided in community pharmacies.

Methods:

We selected a valid and reliable instrument from the literature and translated it to the Persian language. Some new items were added to the first draft based on the special characteristics of the Iranian health system. Then, the feasibility of utilizing the new instrument was assessed. In the third step, we conducted a formal content validity study to calculate content validity indices. Having completed the content validity study, the factorial structure of new instruments was determined by implementing a factorial analysis. Finally, the reliability of the instrument was assessed by assessment of Cronbach's alpha coefficient and test-retest reliability.

Findings:

The developed instrument demonstrated suitable validity and reliability. The final instrument showed desirable content validity, with inter-rater agreement of 94% and 97% for relevance and clarity, respectively. Scale content validity indices for relevance and clarity were calculated as 96% and 92%, respectively, and comprehensiveness was calculated as 100%. Factor analysis resulted in seven factors with a cumulative variance of 62.14%. In internal consistency reliability, Cronbach's alpha for the whole instrument was 0.912. About test-retest reliability, six items showed almost perfect agreement, 18 items showed substantial agreement, and three items showed moderate agreement. Therefore, test-retest reliability assessment too demonstrated appropriate results.

Conclusion:

The instrument demonstrated excellent validity and reliability for application in Iran. This instrument is useful for evaluating patient satisfaction with services provided in community pharmacies in the Persian-speaking communities.

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.

Selective cognitive and psychiatric manifestations in Wolfram Syndrome

BACKGROUND

Wolfram Syndrome (WFS) is known to involve diabetes mellitus, diabetes insipidus, optic nerve atrophy, vision loss, hearing impairment, motor abnormalities, and neurodegeneration, but has been less clearly linked to cognitive, sleep, and psychiatric abnormalities. We sought to determine whether these abnormalities are present in children, adolescents, and young adults with WFS compared to age- and gender-matched individuals with and without type 1 diabetes using standardized measures.

METHODS

Individuals with genetically-confirmed WFS (n = 19, ages 7-27) were compared to age- and gender- equivalent groups of individuals with type 1 diabetes (T1DM; n = 25), and non-diabetic healthy controls (HC: n = 25). Cognitive performance across multiple domains (verbal intelligence, spatial reasoning, memory, attention, smell identification) was assessed using standardized tests. Standardized self- and parent-report questionnaires on psychiatric symptoms and sleep disturbances were acquired from all groups and an unstructured psychiatric interview was performed within only the WFS group.

RESULTS

The three groups were similar demographically (age, gender, ethnicity, parental IQ). WFS and T1DM had similar duration of diabetes but T1DM had higher HbA1C levels than WFS and as expected both groups had higher levels than HC. The WFS group was impaired on smell identification and reported sleep quality, but was not impaired in any other cognitive or self-reported psychiatric domain. In fact, the WFS group performed better than the other two groups on selected memory and attention tasks. However, based upon a clinical evaluation of only WFS patients, we found that psychiatric and behavioral problems were present and consisted primarily of anxiety and hypersomnolence.

CONCLUSIONS

This study found that cognitive performance and psychological health were relatively preserved WFS patients, while smell and sleep abnormalities manifested in many of the WFS patients. These findings contradict past case and retrospective reports indicating significant cognitive and psychiatric impairment in WFS. While many of these patients were diagnosed with anxiety and hypersomnolence, self-reported measures of psychiatric symptoms indicated that the symptoms were not of grave concern to the patients. It may be that cognitive and psychiatric issues become more prominent later in life and/or in later stages of the disease, but this requires standardized assessment and larger samples to determine. In the relatively early stages of WFS, smell and sleep-related symptoms may be useful biomarkers of disease and should be monitored longitudinally to determine if they are good markers of progression as well.

TRIAL REGISTRATION

Current Clinicaltrials.gov Trial NCT02455414 .

Developing a conceptual framework and a tool for measuring access to, and use of, medicines at household level (HH-ATM tool)

OBJECTIVE

To develop a valid and reliable tool to evaluate access to, and use of, medicines at household level (HH-ATM tool).

STUDY DESIGN

The Behavioral Model of Health Services Use was adapted and used as the conceptual framework for developing the HH-ATM tool. Questionnaires were designed (individual and household) based on the conceptual framework and existing tools, including items that captured the characteristics of predisposing, enabling and need factors; health care behaviours; outcomes and impacts.

METHODS

Face validity, content validity and test-retest reliability were assessed using inter-rater agreement, item and scale content validity indices, comprehensiveness indices, and intra-class correlation, kappa and weighted-kappa coefficients.

RESULTS

The household and individual questionnaires demonstrated appropriate validity and reliability. The content validity of household questionnaire was favourable, with inter-rater agreement of 86% and 91% for relevance and clarity, respectively. Scale content validity indices for relevance and clarity were 89% and 91%, respectively, and comprehensiveness was scored at 100%. These indices were also favourable for the individual questionnaire, all scoring 94% or higher.

CONCLUSION

The questionnaires showed excellent validity and reliability for use in Iran. The HH-ATM tool can be implemented to evaluate access to, and use of, medicines in Farsi-speaking communities, and may be useful in other communities if adapted appropriately.

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.

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.