Wolfram Syndrome presenting with optic atrophy and diabetes mellitus: two case reports

MCT1-dependent energetic failure and neuroinflammation underlie optic nerve degeneration in Wolfram syndrome mice

Wolfram syndrome 1 (WS1) is a rare genetic disorder caused by mutations in the WFS1 gene leading to a wide spectrum of clinical dysfunctions, among which blindness, diabetes, and neurological deficits are the most prominent. WFS1 encodes for the endoplasmic reticulum (ER) resident transmembrane protein wolframin with multiple functions in ER processes. However, the WFS1-dependent etiopathology in retinal cells is unknown. Herein, we showed that Wfs1 mutant mice developed early retinal electrophysiological impairments followed by marked visual loss. Interestingly, axons and myelin disruption in the optic nerve preceded the degeneration of the retinal ganglion cell bodies in the retina. Transcriptomics at pre-degenerative stage revealed the STAT3-dependent activation of proinflammatory glial markers with reduction of the homeostatic and pro-survival factors glutamine synthetase and BDNF. Furthermore, label-free comparative proteomics identified a significant reduction of the monocarboxylate transport isoform 1 (MCT1) and its partner basigin that are highly enriched on retinal glia and myelin-forming oligodendrocytes in optic nerve together with wolframin. Loss of MCT1 caused a failure in lactate transfer from glial to neuronal cell bodies and axons leading to a chronic hypometabolic state. Thus, this bioenergetic impairment is occurring concurrently both within the axonal regions and cell bodies of the retinal ganglion cells, selectively endangering their survival while impacting less on other retinal cells. This metabolic dysfunction occurs months before the frank RGC degeneration suggesting an extended time-window for intervening with new therapeutic strategies focused on boosting retinal and optic nerve bioenergetics in WS1.

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.

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.

[Familial Wolfram syndrome]

Wolfram syndrome (WS) is a rare autosomal recessive progressive neurodegenerative disorder, and it is mainly characterized by the presence of diabetes mellitus and optic atrophy. Other symptoms such as diabetes insipidus, deafness, and psychiatric disorders are less frequent. The WFS1 gene, responsible for the disease and encoding for a transmembrane protein called wolframin, was localized in 1998 on chromosome 4p16. In this report, we present a familial observation of Wolfram syndrome (parents and three children). The propositus was a 6-year-old girl with diabetes mellitus and progressive visual loss. Her family history showed a brother with diabetes mellitus, optic atrophy, and deafness since childhood and a sister with diabetes mellitus, optic atrophy, and bilateral hydronephrosis. Thus, association of these familial and personal symptoms is highly suggestive of Wolfram syndrome. The diagnosis was confirmed by molecular analysis (biology), which showed the presence of WFS1 homozygous mutations c.1113G>A (p.Trp371*) in the three siblings and a heterozygote mutation in the parents. Our observation has demonstrated that pediatricians should be aware of the possibility of Wolfram syndrome when diagnosing optic atrophy in diabetic children.

Identification of homozygous WFS1 mutations (p.Asp211Asn, p.Gln486*) causing severe Wolfram syndrome and first report of male fertility

Wolfram syndrome (WFS) is a neurodegenerative genetic condition characterized by juvenile-onset of diabetes mellitus and optic atrophy. We studied clinical features and the molecular basis of severe WFS (neurodegenerative complications) in two consanguineous families from Iran. A clinical and molecular genetic investigation was performed in the affected and healthy members of two families. The clinical diagnosis of WFS was confirmed by the existence of diabetes mellitus and optic atrophy in the affected patients, who in addition had severe neurodegenerative complications. Sequencing of WFS1 was undertaken in one affected member from each family. Targeted mutations were tested in all members of relevant families. Patients had most of the reported features of WFS. Two affected males in the first family had fathered unaffected children. We identified two homozygous mutations previously reported with apparently milder phenotypes: family 1: c.631G>A (p.Asp211Asn) in exon 5, and family 2: c.1456C>T (p.Gln486*) in exon 8. Heterozygous carriers were unaffected. This is the first report of male Wolfram patients who have successfully fathered children. Surprisingly, they also had almost all the complications associated with WFS. Our report has implications for genetic counseling and family planning advice for other affected families.

Wolfram Syndrome: a rare optic neuropathy in youth with type 1 diabetes

Wolfram Syndrome (WS) is a rare, autosomal recessive disorder that causes non-autoimmune type 1 diabetes. The etiology involves a single gene mutation of the wolframin protein inducing endoplasmic reticulum stress and apoptosis in selected cell types with resultant diabetes insipidus, diabetes mellitus, optic atrophy, and sensory-neural deafness. Symptoms are initially absent and signs within the posterior segment of the eye are usually the earliest indicator of WS.These cases characterize unusual and poorly described findings of pigmentary maculopathy in WS and illustrate the importance of collaboration between diabetes and eye care providers; especially in cases of non-autoimmune type 1 diabetes exhibiting atypical human leukocyte-associated antigen haplotypes.

Hypergonadotropic hypogonadism, progressive early-onset spinocerebellar ataxia, and late-onset sensorineural hearing loss: case report and literature review

The association of ataxia, hypergonadotropic hypogonadism and hearing loss is extremely rare. Considerable heterogeneity exists in the literature of the neurological manifestations, age of onset, clinical severity and associated abnormalities. We describe a 24-year-old woman with secondary hypergonadotropic amenorrhea, early-onset progressive spinocerebellar ataxia (SCA), late-onset sensorineural hearing loss and normal intelligence and compare it with reported cases.

Presentation and clinical course of Wolfram (DIDMOAD) syndrome from North India

AIMS

Wolfram syndrome, also known as DIDMOAD, is a relatively rare inherited neurodegenerative disorder, first evident in childhood as an association of juvenile-onset diabetes mellitus and optic atrophy, followed by diabetes insipidus and deafness. The aim of the study was to examine the clinical profile of patients with DIDMOAD syndrome presenting to a tertiary care hospital in north India.

METHODS

Clinical presentation of juvenile-onset diabetes mellitus fulfilling the diagnosis of Wolfram syndrome was studied using a prepared standardized form.

RESULTS

Subjects with juvenile-onset non-autoimmune diabetes mellitus attending the diabetic clinic at a tertiary care centre in north India were followed for 10 years and a diagnosis of fully developed Wolfram syndrome was confirmed in seven individuals. The series consisted of five male and two female patients with a mean age of 17.5 ±7.34 years. Two subjects had consanguinity and none had any other family member affected. Optic atrophy was present in all, sensorineural hearing loss in 4/7, central diabetes insipidus in 4/7 and nephrogenic diabetes insipidus in 2/7 subjects. The new associations found were: spastic myoclonus, short stature with pancreatic malabsorption, nephrogenic diabetes insipidus, cyanotic heart disease and choledocholithiasis with cholangitis. Genetic analysis revealed mutation in exon 8 of the WFS1 gene in all the cases studied.

CONCLUSIONS

The present clinical series of Wolfram syndrome reveals a varied clinical presentation of the syndrome and some new associations.