Mitochondrial DNA 13513G>A Mutation Causing Leber Hereditary Optic Neuropathy Associated With Adult-Onset Renal Failure.

BACKGROUND: Leber hereditary optic neuropathy (LHON) is one of the more common mitochondrial diseases and is rarely associated with mitochondrial renal disease. We report 3 unrelated patients with a background of adult-onset renal failure who presented to us with LHON and were shown to have a heteroplasmic mitochondrial DNA mutation (m.13513G>A). METHODS: Retrospective chart review. RESULTS: All 3 patients had a background of chronic renal failure and presented to us with bilateral optic neuropathy (sequential in 2) and were found to have heteroplasmic m.13513G>A mutations in the MT-ND5 gene. Two of the patients were females (aged 30 and 45 years) with chronic kidney disease from their 20s, attributed to pre-eclampsia, one of whom also had diabetes and sudden bilateral hearing loss. One patient was a male (aged 54 years) with chronic kidney disease from his 20s attributed to IgA nephropathy. His mother had diabetes and apparently sudden bilateral blindness in her 70s. Renal biopsy findings were variable and included interstitial fibrosis, acute tubular necrosis, focal segmental glomerulosclerosis, and IgA/C3 tubular casts on immunofluorescence. Mild improvements in vision followed treatment with either idebenone or a combination supplement including coenzyme Q10, alpha-lipoic acid, and B vitamins. CONCLUSIONS: Our cases expand the clinical syndromes associated with m.13513G>A to include bilateral optic neuropathy and adult-onset renal disease. This highlights that in patients with bilateral, especially sequential, optic neuropathy a broad approach to mitochondrial testing is more useful than a limited LHON panel. Mitochondrial diseases present a diagnostic challenge because of their clinical and genetic variability.

Fundoscopy use in neurology departments and the utility of smartphone photography: a prospective prevalence and crossover diagnostic accuracy study amongst neurology inpatients.

BACKGROUND AND PURPOSE: Although fundoscopy is a crucial part of the neurological examination, it is challenging, under-utilized and unreliably performed. The aim was to determine the prevalence of fundus pathology amongst neurology inpatients and the diagnostic accuracy of current fundoscopy practice compared with systematic screening with smartphone fundoscopy (SF) and portable non-mydriatic fundus photography (NMFP). METHODS: This was a prospective cross-sectional surveillance and diagnostic accuracy study on adult patients admitted under neurology in an Australian hospital. Inpatients were randomized to initial NMFP (RetinaVue 100, Welch Allyn) or SF (D-EYE) followed by a crossover to the alternative modality. Images were graded by neurology doctors, using telemedicine consensus neuro-ophthalmology NMFP grading as the reference standard. Feasibility parameters included ease, comfort and speed. RESULTS: Of 79 enrolled patients, 14.1% had neurologically relevant pathology (seven, disc pallor; one, hypertensive retinopathy; three, disc swelling). The neurology team performed direct ophthalmoscopy in 6.6% of cases and missed all abnormalities. SF had a sensitivity of 30%-40% compared with NMFP (45.5%); however, it had a lower rate of screening failure (1% vs. 13%, p < 0.001), a shorter examination time (1.10 vs. 2.25 min, p < 0.001) and a slightly higher patient comfort rating (9.2 vs. 8/10, p < 0.001). CONCLUSION: Our study demonstrates a clinically significant prevalence of fundus pathology amongst neurology inpatients which was missed by current fundoscopy practices. Portable NMFP screening appears more accurate than SF, whilst both are diagnostically superior to routine fundoscopic practice, feasible and well tolerated by patients.

Use of Whole-Genome Sequencing for Mitochondrial Disease Diagnosis.

BACKGROUND AND OBJECTIVES: Mitochondrial diseases (MDs) are the commonest group of heritable metabolic disorders. Phenotypic diversity can make molecular diagnosis challenging, and causative genetic variants may reside in either mitochondrial or nuclear DNA. A single comprehensive genetic diagnostic test would be highly useful and transform the field. We applied whole-genome sequencing (WGS) to evaluate the variant detection rate and diagnostic capacity of this technology with a view to simplifying and improving the MD diagnostic pathway. METHODS: Adult patients presenting to a specialist MD clinic in Sydney, Australia, were recruited to the study if they satisfied clinical MD (Nijmegen) criteria. WGS was performed on blood DNA, followed by clinical genetic analysis for known pathogenic MD-associated variants and MD mimics. RESULTS: Of the 242 consecutive patients recruited, 62 participants had "definite," 108 had "probable," and 72 had "possible" MD classification by the Nijmegen criteria. Disease-causing variants were identified for 130 participants, regardless of the location of the causative genetic variants, giving an overall diagnostic rate of 53.7% (130 of 242). Identification of causative genetic variants informed precise treatment, restored reproductive confidence, and optimized clinical management of MD. DISCUSSION: Comprehensive bigenomic sequencing accurately detects causative genetic variants in affected MD patients, simplifying diagnosis, enabling early treatment, and informing the risk of genetic transmission.

Dystonia Responsive to Dopamine: POLG Mutations Should Be Considered If Sensory Neuropathy Is Present.

The POLG gene encodes mitochondrial DNA polymerase, and mutations in this gene cause a spectrum of disorders related to mitochondrial DNA depletion or deletion. Dystonia has only rarely been reported as an early and prominent manifestation of POLG mutations. We report a case of a 30-year-old male presenting with lower limb dystonia with peripheral neuropathy and demonstrate that the dystonia was levodopa responsive (with video findings). Whole-genome sequencing revealed biallelic variants in the POLG gene: a known pathogenic variant [NM_001126131.2:c.2209G>C (p.Gly737Arg)] and a novel likely pathogenic variant [NM_001126131.2:c.3305A>C (p.Gln1102Pro)]. A genetic diagnosis was made before the appearance of more readily recognizable features of mitochondrial disease, allowing us to avoid invasive tissue biopsies or potentially deleterious treatments, such as sodium valproate. A POLG-related disorder should be suspected in cases of dystonia with peripheral neuropathy, and this diagnosis may have implications for further investigations and management.

Bruch's Membrane Opening Minimum Rim Width Provides Objective Differentiation between Glaucoma and Nonglaucomatous Optic Neuropathies.

PURPOSE: A challenging clinical scenario is distinguishing between normal tension glaucoma (NTG) and non-glaucomatous optic neuropathies (NGON). The key to the assessment remains identifying the presence of optic nerve head cupping. Recent optical coherence tomography (OCT) measurements now allow objective assessment of cupping by minimum rim width at Bruch's membrane opening (MRW-BMO). This study assessed the hypothesis that the MRW-BMO measurement quantifies cupping and therefore can differentiate between NTG and NGON. DESIGN: Diagnostic evaluation with area under the curve. METHODS: Setting: multicenter tertiary hospitals and outpatient clinics. PATIENT POPULATION: 81 eyes of 81 patients were enrolled, 27 with NTG and 54 with NGON, including ischemic optic neuropathy, previous optic neuritis, and compressive and inherited optic neuropathies. All NGON patients with intraocular pressure >21 mm Hg, narrow drainage angles, or a family history of glaucoma were excluded. Observational procedure: optic disc OCT images were obtained of both the retinal nerve fiber layer thickness and the MRW-BMO. MAIN OUTCOME MEASUREMENTS: the utility of the MRW-BMO in differentiating GON from NGON was assessed using the area under the curve (AUC) estimated from a logistic regression model. RESULTS: The 5-fold cross-validated AUC for glaucoma versus nonglaucoma from logistic regression models using MRW-BMO values from all sectors was 0.95 (95% confidence interval: 0.86-1.00). CONCLUSIONS: The measurement of MRW-BMO effectively differentiates between NTG and NGON with a high level of sensitivity and specificity. Incorporating this measurement into routine glaucoma assessment may provide a robust method of assisting clinicians to improve diagnosis and therefore treatment of optic nerve diseases.

Fundus Autofluorescence in Maternally Inherited Diabetes and Deafness: The Gold Standard for Monitoring Maculopathy?

Maternally inherited diabetes and deafness (MIDD) is a mitochondrial disease associated with dysfunction of the retinal pigment epithelium and photoreceptor outer segments in a peri-foveal arrangement. If chorioretinal atrophy develops, patients risk losing vision. We retrospectively analysed three patients with genetically proven MIDD, assessing atrophy size and progression using overlay in photoshop. Patients showed increase in chorioretinal atrophy of 205%, 46% and 34%, respectively. We also found location-specific progression, where hyper-autofluorescent deposits evolved into areas of atrophy. These results support the use of fundus autofluorescence as a valuable tool in monitoring disease progression and providing prognostic information for clinicians and patients.

A Case of Acute Myeloid Leukaemia Presenting as Subacute Intracranial Hypertension in a Young Adult.

We report a case of an 18-year-old woman presenting with headache, papilloedema, and cerebrospinal fluid (CSF) pleocytosis. She was subsequently diagnosed with acute myeloid leukaemia, which is to date the only reported case manifesting as central nervous system-localised disease in an adult. The intracranial hypertension was treated successfully with chemotherapy, acetazolamide, and CSF drainage, with no permanent visual impairment. The mechanism by which haematological malignancy causes intracranial hypertension is not fully elucidated, but we hypothesise that in our case, blast infiltration interfered with CSF reabsorption at the arachnoid granulations.

The neuro-ophthalmology of inherited myopathies.

PURPOSE OF REVIEW: Inherited myopathies, and in particular mitochondrial myopathies, are heterogeneous disorders, and ocular manifestations may be the presenting feature or offer important diagnostic clues. The ophthalmologist may be key to diagnosis, facilitating recognition of associated potentially life-threatening organ manifestations and an integral part of multidisciplinary care. This review, focusing especially on mitochondrial myopathies, provides updates on clinical features, diagnosis and recent therapeutic developments. RECENT FINDINGS: Ptosis and/or ophthalmoplegia is present in over half of patients with mitochondrial disease, and associated clinical features imply specific genetic associations. Advances in next-generation sequencing have led to rapid evolution in the field, improving diagnosis rates, facilitating identification of novel genes, mutations and phenotypes, and providing important insights into disease mechanisms and therapeutic possibilities. Improved understanding of molecular mechanisms in inherited myopathies is enabling the development of experimental molecular therapies with clinical potential. SUMMARY: Genetic advances are driving progress in the field of inherited myopathies, influencing diagnosis, understanding of disease and development of therapies. Recognition of key features can impact diagnosis and management of these important conditions.

Long-term Ergotamine Derivative Therapy for Migraine Associated with Pachymeningitis and Sixth Cranial Nerve Palsy.

Chronic use of ergotamine derivatives has been well described in the literature to cause retroperitoneal, pleural, pericardial and valvular fibrosis. While acute migraine treatment advances have resulted in a reduction of ergotamine derivatives prescribing, they are still considered appropriate for some patients. We report a case of diffuse pachymeningitis with symptomatic right sixth cranial nerve palsy who had a history of long-term Cafergot© suppository use. To the best of our knowledge, this is the first case to temporally associate ergotamine derivatives with pachymeningitis.

High Degree of Genetic Heterogeneity for Hereditary Cerebellar Ataxias in Australia.

Genetic testing strategies such as next-generation sequencing (NGS) panels and whole genome sequencing (WGS) can be applied to the hereditary cerebellar ataxias (HCAs), but their exact role in the diagnostic pathway is unclear. We aim to determine the yield from genetic testing strategies and the genetic and phenotypic spectrum of HCA in Australia by analysing real-world data. We performed a retrospective review on 87 HCA cases referred to the Neurogenetics Clinic at the Royal North Shore Hospital, Sydney, Australia. Probands underwent triplet repeat expansion testing; those that tested negative had NGS-targeted panels and WGS testing when available. In our sample, 58.6% were male (51/87), with an average age at onset of 37.1 years. Individuals with sequencing variants had a prolonged duration of illness compared to those with a triplet repeat expansion. The detection rate in probands for routine repeat expansion panels was 13.8% (11/80). NGS-targeted panels yielded a further 11 individuals (11/32, 34.4%), with WGS yielding 1 more diagnosis (1/3, 33.3%). NGS panels and WGS improved the overall diagnostic rate to 28.8% (23/80) in 14 known HCA loci. The genetic findings included novel variants in ANO10, CACNA1A, PRKCG and SPG7. Our findings highlight the genetic heterogeneity of HCAs and support the use of NGS approaches for individuals who were negative on repeat expansion testing. In comparison to repeat disorders, individuals with sequencing variants may have a prolonged duration of illness, consistent with slower progression of disease.

Surgical Technique for Pulled in Two Syndrome: Three Cases With Chronic Progressive External Ophthalmoplegia.

The authors describe three examples of "pulled in two syndrome" (PITS) from a series of 13 patients undergoing strabismus surgery with underlying chronic progressive external ophthalmoplegia (CPEO) and illustrate techniques for recovery of the "pulled in two" extraocular muscle should the complication arise. In all cases, a rectus muscle snapped under minimal tension while held on a strabismus hook during strabismus surgery. Two patients suffered from CPEO as a result of genetic mitochondrial disease, whereas one resulted from presumed mitochondrial toxicity induced by HAART. In cases 1 and 3, the proximal medial rectus segment was retrieved and reattached. In case 2, the fragmented superior rectus muscle was too friable to be reattached. All three patients were satisfied with the outcome, having reduced their angles of misalignment postoperatively. All three had improved cosmesis, and the two who had complained of diplopia preoperatively found their diplopia to be eliminated or improved. With anticipation of muscle friability in patients with previous extraocular surgery or degenerative muscle changes such as CPEO, the likelihood of the complication arising may be reduced. Should it occur, the loss of a snapped rectus muscle may be avoided through careful manipulation of the globe. [J Pediatr Ophthalmol Strabismus. 2017;54:e83-e87.].

Beyond what the eye can see.

A 45-year-old woman presented with acute sequential optic neuropathy resulting in bilateral complete blindness. No significant visual recovery occurred. Past medical history was relevant for severe preeclampsia with resultant renal failure, diabetes mellitus, and sudden bilateral hearing loss when she was 38 years old. There was a family history of diabetes mellitus in her mother. Testing for common causes of bilateral optic neuropathy did not reveal a diagnosis for her illness. The maternal and personal history of diabetes and deafness prompted testing for mitochondrial disease. The 3 primary mitochondrial DNA mutations responsible for Leber hereditary optic neuropathy were absent, but the patient was subsequently found to have a disease causing mitochondrial DNA mutation, m.13513G>A. The case illustrates the importance of early testing for mitochondrial disease and demonstrates that Leber hereditary optic neuropathy-like presentations may be missed if testing is limited to the 3 primary mutations.

Functional neurological disorders in outpatient practice: An Australian cohort.

Functional disorders are defined as neurological symptoms without causative organic pathology identified. They are a diverse and often neglected group of disorders. The aim of this was to determine the incidence and outcome of functional neurological disorders in an Australian neurology practice. Over a 17month period, all patients presenting to a single outpatient neurology service were evaluated to determine the incidence and outcome of these disorders. A total of 884 patients were assessed and of these, 137 had a final diagnosis of functional neurological illness, equating to an incidence of 15% of all patients seen. Functional disorders were the third most common presentation overall. Patients with functional disorders were younger, more likely to be female and had a higher rate of current psychiatric comorbidity compared to other neurology patients. Sensory symptoms were the most common manifestation (48%) followed by limb weakness (37%) and psychogenic non-epileptic seizures (14%). Outcome information was available for 49% of patients at an average of 3months follow-up. 45% had some improvement in their symptoms, 43% had static symptoms and 12% had worsening of symptoms. This study confirms the high incidence of functional disorders in outpatient neurology practice. Early improvement was seen in a substantial proportion of patients and is influenced by duration of symptoms.

C9orf72 expansion presenting as an eating disorder.

This report describes a 64-year-old woman with a strong family history of motor neuron disease, whose diagnosis of behavioural variant frontotemporal dementia was delayed due to her initial presentation with atypical manifestations, including restriction of oral intake resulting in low weight, disordered eating and anxiety. Upon investigation, she was found to be a carrier of the C9orf72 hexanucleotide repeat expansion. Our case supports previous publications asserting that C9orf72 mutation carriers manifest with diverse clinical syndromes, and expands the phenotype to include anorexia and food refusal as potential features of the condition.

The broadening spectrum of mitochondrial disease: shifts in the diagnostic paradigm.

BACKGROUND: The diagnosis of mitochondrial disease requires a complex synthesis of clinical, biochemical, histological, and genetic investigations. An expanding number of mitochondrial diseases are being recognized, despite their phenotypic diversity, largely due to improvements in methods to detect mutations in affected individuals and the discovery of genes contributing to mitochondrial function. Improved understanding of the investigational pitfalls and the development of new laboratory methodologies that lead to a molecular diagnosis have necessitated the field to rapidly adopt changes to its diagnostic approach. SCOPE OF REVIEW: We review the clinical, investigational and genetic challenges that have resulted in shifts to the way we define and diagnose mitochondrial disease. Incorporation of changes, including the use of fibroblast growth factor 21 (FGF-21) and next generation sequencing techniques, may allow affected patients access to earlier molecular diagnosis and management. MAJOR CONCLUSIONS: There have been important shifts in the diagnostic paradigm for mitochondrial disease. Diagnosis of mitochondrial disease is no longer reliant on muscle biopsy alone, but should include clinical assessment accompanied by the use of serological biomarkers and genetic analysis. Because affected patients will be defined on a molecular basis, oligosymptomatic mutation carriers should be included in the spectrum of mitochondrial disease. Use of new techniques such as the measurement of serum FGF-21 levels and next-generation-sequencing protocols should simplify the diagnosis of mitochondrial disease. GENERAL SIGNIFICANCE: Improvements in the diagnostic pathway for mitochondrial disease will result in earlier, cheaper and more accurate methods to identify patients with mitochondrial disease. This article is part of a Special Issue entitled Frontiers of Mitochondrial Research.

"Peering at the Tip of the Nose" as a Sign of Thalamic Haemorrhage.

A 76-year-old female presented with sudden onset of left hemiplegia and hemianaesthesia. Examination revealed tonic downward deviation of both eyes and esodeviation of the left eye, with no upgaze beyond midline and mild abduction deficits bilaterally. Bilateral ptosis was seen, reflecting partial levator dehiscence compounded by pseudoptosis due to the depressed position of the eyes. "Peering at the tip of the nose" sign, reflecting acute downward and esodeviation of the eyes, is highly suggestive of thalamic haemorrhage. It is thought to reflect damage to the mesodiencephalic junction, which contains structures important for vertical gaze and vergence. Awareness of this sign may assist clinicians with the correct anatomical localisation of stroke in patients who present with thalamic haemorrhage.