The Wolfram-like variant WFS1E864K destabilizes MAM and compromises autophagy and mitophagy in human and mice.

Dominant variants in WFS1 (wolframin ER transmembrane glycoprotein), the gene coding for a mitochondria-associated endoplasmic reticulum (ER) membrane (MAM) resident protein, have been associated with Wolfram-like syndrome (WLS). In vitro and in vivo, WFS1 loss results in reduced ER to mitochondria calcium (Ca2+) transfer, mitochondrial dysfunction, and enhanced macroautophagy/autophagy and mitophagy. However, in the WLS pathological context, whether the mutant protein triggers the same cellular processes is unknown. Here, we show that in human fibroblasts and murine neuronal cultures the WLS protein WFS1E864K leads to decreases in mitochondria bioenergetics and Ca2+ uptake, deregulation of the mitochondrial quality system mechanisms, and alteration of the autophagic flux. Moreover, in the Wfs1E864K mouse, these alterations are concomitant with a decrease of MAM number. These findings reveal pathophysiological similarities between WS and WLS, highlighting the importance of WFS1 for MAM's integrity and functionality. It may open new treatment perspectives for patients with WLS.Abbreviations: BafA1: bafilomycin A1; ER: endoplasmic reticulum; HSPA9/GRP75: heat shock protein family A (Hsp70) member 9; ITPR/IP3R: inositol 1,4,5-trisphosphate receptor; MAM: mitochondria-associated endoplasmic reticulum membrane; MCU: mitochondrial calcium uniporter; MFN2: mitofusin 2; OCR: oxygen consumption rate; ROS: reactive oxygen species; ROT/AA: rotenone+antimycin A; VDAC1: voltage dependent anion channel 1; WLS: Wolfram-like syndrome; WS: Wolfram syndrome; WT: wild-type.

A Wolfram-like syndrome family: Case report.

BACKGROUND: Wolfram-like syndrome (WFLS) is an autosomal dominant inherited disease characterized by a single heterozygous pathogenic variant in the WFS1 gene. Its clinical presentation is similar to autosomal recessive Wolfram syndrome. CASE PRESENTATION: We reported a case of a 10-year-old boy and his family members who initially experienced hearing impairment (HI), followed by optic atrophy. Genetic testing revealed the presence of a WFS1 variant (chr4-6302385 exon8 NM_006005.3: c.2590G > A, p. Glu864Lys). CONCLUSION: Wolfram-like syndrome, a rare neurodegenerative genetic disorder, manifested as deafness, optic atrophy, and diabetes mellitus. There hasn't been a definite treatment yet. Early identification of the variant in the WFS1 gene is beneficial for genetic counseling.

WFS1 autosomal dominant variants linked with hearing loss: update on structural analysis and cochlear implant outcome.

BACKGROUND: Wolfram syndrome type 1 gene (WFS1), which encodes a transmembrane structural protein (wolframin), is essential for several biological processes, including proper inner ear function. Unlike the recessively inherited Wolfram syndrome, WFS1 heterozygous variants cause DFNA6/14/38 and wolfram-like syndrome, characterized by autosomal dominant nonsyndromic hearing loss, optic atrophy, and diabetes mellitus. Here, we identified two WFS1 heterozygous variants in three DFNA6/14/38 families using exome sequencing. We reveal the pathogenicity of the WFS1 variants based on three-dimensional (3D) modeling and structural analysis. Furthermore, we present cochlear implantation (CI) outcomes in WFS1-associated DFNA6/14/38 and suggest a genotype-phenotype correlation based on our results and a systematic review. METHODS: We performed molecular genetic test and evaluated clinical phenotypes of three WFS1-associated DFNA6/14/38 families. A putative WFS1-NCS1 interaction model was generated, and the impacts of WFS1 variants on stability were predicted by comparing intramolecular interactions. A total of 62 WFS1 variants associated with DFNA6/14/38 were included in a systematic review. RESULTS: One variant is a known mutational hotspot variant in the endoplasmic reticulum (ER)-luminal domain WFS1(NM_006005.3) (c.2051 C > T:p.Ala684Val), and the other is a novel frameshift variant in transmembrane domain 6 (c.1544_1545insA:p.Phe515LeufsTer28). The two variants were pathogenic, based on the ACMG/AMP guidelines. Three-dimensional modeling and structural analysis show that non-polar, hydrophobic substitution of Ala684 (p.Ala684Val) destabilizes the alpha helix and contributes to the loss of WFS1-NCS1 interaction. Also, the p.Phe515LeufsTer28 variant truncates transmembrane domain 7-9 and the ER-luminal domain, possibly impairing membrane localization and C-terminal signal transduction. The systematic review demonstrates favorable outcomes of CI. Remarkably, p.Ala684Val in WFS1 is associated with early-onset severe-to-profound deafness, revealing a strong candidate variant for CI. CONCLUSIONS: We expanded the genotypic spectrum of WFS1 heterozygous variants underlying DFNA6/14/38 and revealed the pathogenicity of mutant WFS1, providing a theoretical basis for WFS1-NCS1 interactions. We presented a range of phenotypic traits for WFS1 heterozygous variants and demonstrated favorable functional CI outcomes, proposing p.Ala684Val a strong potential marker for CI candidates.

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.

Case report: De novo pathogenic variant in WFS1 causes Wolfram-like syndrome debuting with congenital bilateral deafness.

Background: Congenital deafness could be the first manifestation of a syndrome such as in Usher, Pendred, and Wolfram syndromes. Therefore, a genetic study is crucial in this deficiency to significantly improve its diagnostic efficiency, to predict the prognosis, to select the most adequate treatment required, and to anticipate the development of other associated clinical manifestations. Case presentation: We describe a young girl with bilateral congenital profound deafness, who initially received a single cochlear implant. The genetic study of her DNA using a custom-designed next-generation sequencing (NGS) panel detected a de novo pathogenic heterozygous variant in the WFS1 gene related to Wolfram-like syndrome, which is characterized by the presence of other symptoms such as optic atrophy. Due to this diagnosis, a second implant was placed after the optic atrophy onset. The speech audiometric results obtained with both implants indicate that this work successfully allows the patient to develop normal speech. Deterioration of the auditory nerves has not been observed. Conclusion: The next-generation sequencing technique allows a precise molecular diagnosis of diseases with high genetic heterogeneity, such as hereditary deafness, while this was the only symptom presented by the patient at the time of analysis. The NGS panel, in which genes responsible for both syndromic and non-syndromic hereditary deafness were included, was essential to reach the diagnosis in such a young patient. Early detection of the pathogenic variant in the WFS1 gene allowed us to anticipate the natural evolution of the disease and offer the most appropriate management to the patient.

Novel missense WFS1 variant causing autosomal dominant atypical Wolfram syndrome.

BACKGROUND: In contrast to the classic autosomal recessive Wolfram syndrome, Wolfram-like syndrome (WLS) is an autosomal dominant disease caused by heterozygous variants in the WFS1 gene. Here, we present deep phenotyping of a mother and son with a WFS1 variant NM_006005.3:c.2508 G > T, p. (Lys836Asn) detected with next-generation sequencing, which is novel at the nucleotide level. In this Greek family, the proband and mother had sensorineural hearing loss and mild non-progressive vision loss with optic nerve atrophy. An initial optic atrophy panel that did not test for WFS1 was unremarkable, but a broader inherited retinal dystrophy panel found the WFS1 variant. CONCLUSION: This study highlights the importance of including WFS1 sequencing in the evaluation of optic nerve atrophy to discover syndromic conditions.

[Hereditary optic neuropathies in pediatric ophthalmology]. / Neuropathies optiques héréditaires en ophtalmo-pédiatrie.

INTRODUCTION: Hereditary optic neuropathies (HON) often begin in adulthood. However, some of them can have an early onset. These may have specific clinical features and natural histories. PATIENTS AND METHODS: Retrospective study of HON patients with onset before the age of 14 years seen in a referral center. In addition to the age of onset, we evaluated the genetic etiology, visual acuity at 15 years, last best corrected visual acuity, optic disc appearance, visual field and extra-ophthalmological manifestations. RESULTS: Forty-four patients (16 women) were included; i.e. 27.8% of all patients followed for HON. The mean age of onset was 8.5±3.3 years, with an onset earlier than 3 years in 5 patients. An etiology was not found in 8 patients. Of the remaining 36 patients, 12 had Leber's hereditary optic neuropathy (LHON), 11 had dominant optic atrophy, 12 had WS/WS-like syndrome, 2 had recessive optic atrophy and 1 had spastic paraplegia type 7. For 78 eyes of 40 patients (mean age 26.9±14.5 years), the mean last visual acuity was 0.80±0.33 LogMAR, with differences according to genetic forms. Visual acuity was less than or equal to counting fingers for 7 eyes (29.1%) of 4 WS/WS-like patients and one LHON patient. CONCLUSION: Early onset NOH are not unusual. Their visual prognosis is as severe as adult onset NOH, with variations depending on the underlying genetic causes.