SENIOR-LØKEN SYNDROME: A Case Series and Review of the Renoretinal Phenotype and Advances of Molecular Diagnosis

PURPOSE

To report genetic and clinical findings in a case series of 10 patients from eight unrelated families diagnosed with Senior-Løken syndrome.

METHODS

A retrospective study of patients with Senior-Løken syndrome. Data collected included clinical findings electroretinography and ocular imaging. Genetic analysis was based on molecular inversion probes, whole-exome sequencing (WES), and Sanger sequencing.

RESULTS

All patients who underwent electrophysiology (8/10) had widespread photoreceptor degeneration. Genetic analysis revealed two mutations in NPHP1, two mutations in NPHP4, and two mutations in IQCB1 (NPHP5). Five of the six mutations identified in the current study were found in a single family each in our cohort. The IQCB1-p.R461* mutation has been identified in 3 families. Patients harboring mutations in IQCB1 were diagnosed with Leber congenital amaurosis, while patients with NPHP4 and NPHP1 mutations showed early and sector retinitis pigmentosa, respectively. Full-field electroretinography was extinct for 6 of 10 patients, moderately decreased for two, and unavailable for another 2 subjects. Renal involvement was evident in 7/10 patients at the time of diagnosis. Kidney function was normal (based on serum creatinine) in patients younger than 10 years. Mutations in IQCB1 were associated with high hypermetropia, whereas mutations in NPHP4 were associated with high myopia.

CONCLUSION

Patients presenting with infantile inherited retinal degeneration are not universally screened for renal dysfunction. Modern genetic tests can provide molecular diagnosis at an early age and therefore facilitate early diagnosis of renal disease with recommended periodic screening beyond childhood and family planning.

Clinical assessment and FGFR2 mutation analysis in a Chinese family with Crouzon syndrome: A case report

RATIONALE

Crouzon syndrome is an autosomal dominant genetic disorder caused by mutations in fibroblast growth factor receptor 2 (FGFR2) and one of the most common types of craniosynostosis. Here we report the detection of FGFR2 mutation and its related clinical findings in 2 patients with Crouzon syndrome from a Chinese family.

PATIENT CONCERNS

We report a case of a 28-year-old male patient presented with the chief complaint of gradually blurring of his eyes over the last 6 months before visiting our clinics. History revealed low visual acuity in his right eye since childhood. Physical examination showed that both the patient and his mother have the appearance of craniofacial dysostosis, mandibular prognathism, ocular proptosis, short superior lip, scoliosis, and thoracic deformity.

DIAGNOSIS

Auxiliary examinations lead to the diagnosis of Crouzon syndrome with binocular optic atrophy, myelinated retina nerve fibers, and ametropia in both eyes, and amblyopia in the right eye of the male patient. The molecular genetic analysis confirmed the diagnosis by detecting a heterozygous pathogenic mutation c.1026C > G (C342W) in exon 10 of FGFR2 in both the patient and his mother, but not in any of the unaffected family members.

INTERVENTIONS AND OUTCOMES

None.

LESSONS

Our study confirms the presence of optic nerve atrophy in patients with Crouzon syndrome carrying FGFR2 C342W mutations and indicates that MRI and funduscopy should be performed to examine the optic nerve changes for patients with Crouzon syndrome.

From Transcriptomics to Treatment in Inherited Optic Neuropathies

Inherited optic neuropathies, including Leber Hereditary Optic Neuropathy (LHON) and Dominant Optic Atrophy (DOA), are monogenetic diseases with a final common pathway of mitochondrial dysfunction leading to retinal ganglion cell (RGC) death and ultimately loss of vision. They are, therefore, excellent models with which to investigate this ubiquitous disease process-implicated in both common polygenetic ocular diseases (e.g., Glaucoma) and late-onset central nervous system neurodegenerative diseases (e.g., Parkinson disease). In recent years, cellular and animal models of LHON and DOA have matured in parallel with techniques (such as RNA-seq) to determine and analyze the transcriptomes of affected cells. This confluence leaves us at a particularly exciting time with the potential for the identification of novel pathogenic players and therapeutic targets. Here, we present a discussion of the importance of inherited optic neuropathies and how transcriptomic techniques can be exploited in the development of novel mutation-independent, neuroprotective therapies.

Toxic-Metabolic and Hereditary Optic Neuropathies

PURPOSE OF REVIEW

The diagnosis of visual loss from toxic-metabolic and hereditary optic neuropathies may be delayed in some cases because of a failure to elicit important information in the clinical history or to recognize typical examination findings. An understanding of the features specific to each type of toxic-metabolic and hereditary optic neuropathy, and of the underlying mechanism of insult to the optic nerve, could lead to earlier recognition, diagnosis, and treatment (when available).

RECENT FINDINGS

Understanding of the role of mitochondria in toxic-metabolic and hereditary optic neuropathies is growing, particularly regarding the mechanism of insult of certain agents (medications and toxins) and of vitamin B12 deficiency. New developments in the quest for treatment for hereditary optic neuropathy, specifically Leber hereditary optic neuropathy, are being seen.

SUMMARY

Toxic-metabolic and hereditary optic neuropathies present in a similar fashion, with painless, progressive, bilateral visual loss with dyschromatopsia and cecocentral visual field defects. The associated retinal ganglion cell and axonal loss is typically due to mitochondrial dysfunction caused by an exogenous agent (toxic), by insufficient or deficient substrate (metabolic or nutritional), or by abnormal proteins or mitochondrial structure determined by a genetic mutation (hereditary).

Molecular Study of Nephronophthisis in 7 Unrelated Pakistani Families

Nephronophthisis is an autosomal recessive cystic kidney disease characterized by tubular interstitial infiltration, periglomerular fibrosis, and cysts, and is the most frequent genetic cause of end-stage renal disease in children. Nephronophthisis is pleiotropic as almost all the causative genes are involved in primary cilium and centrosome function which are found in almost all human cells. Genetic heterogeneity in nephronophthisis makes the molecular and genetic diagnosis somewhat difficult. Homozygous deletions in the nephronophthisis 1 (NPHP1) gene are the major contributor of nephronophthisis cases, while other genes accounts for less than 3% each. Nephronophthisis-related ciliopathy is a term used for extrarenal symptoms in addition to nephronophthisis. Herein, we are reporting the molecular study of 7 children from independent families fulfilling the criteria of nephronophthisis. A deletion analysis of the NPHP1 gene was performed in each case, and NPHP5 mutation screening was performed in the absence of such deletion in patients with Senior Loken syndrome.

Leigh syndrome: Resolving the clinical and genetic heterogeneity paves the way for treatment options

Leigh syndrome is a progressive neurodegenerative disorder, affecting 1 in 40,000 live births. Most patients present with symptoms between the ages of three and twelve months, but adult onset Leigh syndrome has also been described. The disease course is characterized by a rapid deterioration of cognitive and motor functions, in most cases resulting in death due to respiratory failure. Despite the high genetic heterogeneity of Leigh syndrome, patients present with identical, symmetrical lesions in the basal ganglia or brainstem on MRI, while additional clinical manifestations and age of onset varies from case to case. To date, mutations in over 60 genes, both nuclear and mitochondrial DNA encoded, have been shown to cause Leigh syndrome, still explaining only half of all cases. In most patients, these mutations directly or indirectly affect the activity of the mitochondrial respiratory chain or pyruvate dehydrogenase complex. Exome sequencing has accelerated the discovery of new genes and pathways involved in Leigh syndrome, providing novel insights into the pathophysiological mechanisms. This is particularly important as no general curative treatment is available for this devastating disorder, although several recent studies imply that early treatment might be beneficial for some patients depending on the gene or process affected. Timely, gene-based personalized treatment may become an important strategy in rare, genetically heterogeneous disorders like Leigh syndrome, stressing the importance of early genetic diagnosis and identification of new genes/pathways. In this review, we provide a comprehensive overview of the most important clinical manifestations and genes/pathways involved in Leigh syndrome, and discuss the current state of therapeutic interventions in patients.

[Modern opportunities and prospects for studying pathogenesis, diagnosing and treating hereditary optic neuropathies]

OBJECTIVE

To evaluate modern opportunities and prospects for studying pathogenesis and improving diagnostics and treatment of hereditary optic neuropathies (HON).

MATERIAL AND METHODS

The article presents summarized data on the pathogenesis, diagnostics, and treatment of HON based on modern methods of assessment.

RESULTS

The results of long-term worldwide studies and those performed in the Research Institute of Eye Diseases in collaboration with several other institutions are presented. Genetic testing for mitochondrial and nucleus DNA mutations that have a known association with Leber's hereditary optic neuropathy (LHON) and autosomal dominant optic neuropathy (ADON) allow verification only in half of the cases. Particular features of hereditary diseases, such as incomplete penentrance, variable expression, clinical polymorphism, difficulties in detection of hereditary sings, and genetic heterogeneity, are shown to complicate the diagnosis of HON. Spectral retinal tomography revealed characteristic morphometric changes in the macular region and peripapillary nerve fiber layer in the acute stage of LHON. Hereditary optic neuropathies result from a genetically determined decrease in mitochondrial respiratory chain complexes activity, which is associated with a decrease in ATP production. From that standpoint, studying of mitochondrial oxidative phosphorylation biochemical defects in LHON and ADON is an option for detection of mitochondrial dysfunction. Results of a newly proposed method of mitochondrial membrane potential assessment in skin fibroblasts, which can be used for differential diagnosis of mitochondrial optic nerve diseases, are presented. Possible therapeutic measures for HON are discussed.

CONCLUSION

In the prevailing number of cases the described clinical, molecular genetic, and cytological methods ensure proper diagnosis of hereditary optic neuropathies. Prospects of HON treatment, rather ambiguous, are associated with further studying of pathogenesis, development of drugs and gene therapy.

[Hereditary optic neuropathies: clinical and molecular genetic characteristics]

The article presents a review of literature on hereditary optic neuropathies: Leber mitochondrial hereditary optic neuropathy, autosomal dominant and autosomal recessive optic neuropathies, X-linked optic atrophy. Clinical and molecular genetic characteristics are covered. Isolated optic neuropathies, as well as hereditary optic disorders, being a part of a complex syndromic disease are described.

GAPO syndrome associated with pyoderma vegetans: an unreported co-existence

GAPO syndrome is a rare autosomal recessive disease and an acronym composed of growth retardation, alopecia, pseudoanodontia, optic atrophy. Approximately 38 cases have been reported in literature until now. Pyoderma vegetans is a chronic inflammatory disease characterized with vesicopustular, exudative and vegetative lesions usually localized on face, scalp, axilla and genitalia. Pyoderma vegetans is attributed to a bacterial infection frequently occurring in individuals with an underlying immunosuppressive condition. A 30-year-old female patient was admitted to our clinic with complaint of a hemorrhagic, crusted, exudative vegetative two plaques on the scalp. On her physical examination, she had a prematurely aged face, predominant lower lips, total tooth loss, frontal bossing, enlarged anterior fontanelle, marked scalp veins, micrognatia, depressed nasal bridge, short stature, growth retardation. She was diagnosed as GAPO syndrome as the result of her physical examination. Result of the biopsy taken from scalp was evaluated as pyoderma vegetans. And the diagnosis of pyoderma vegetans was established based on the correlate of both clinical and histopathologic findings. Pyoderma vegetans coexisting with GAPO syndrome has not been reported previously. Thus we wished to report it.

[Electrophysiological tests in early and differential diagnosis of some hereditary retinal and optic nerve diseases]

PURPOSE

The goal of our study was to determine the value of electrophysiological tests in early and differential diagnosis of some hereditary retinal and optic nerve diseases.

MATERIAL AND METHODS

Review article on the basis of own experiences and results of another authors concerning to EOG, ERG, PERG, MfERG and VEP tests in evaluation of hereditary, stationary and progressive retinal diseases, as well as optic nerve diseases.

RESULTS

Electrophysiological tests can be abnormal even in patients without fundus changes seen in routine ophthalmological examination.

CONCLUSIONS

Electrophysiological tests are useful in early and differential diagnosis of some hereditary retinal and optic nerve diseases. General ophthalmologists should remember about its application, especially in difficult diagnostic cases.

Leber hereditary optic neuropathy, progressive visual loss, and multiple-sclerosis-like symptoms

PURPOSE

To report a case of Leber hereditary optic neuropathy with multiple-sclerosis-like symptoms.

METHODS

Observational case report. A 34-year-old man was found to have Leber hereditary optic neuropathy and a mutation at position 11778 of the mitochondrial genome. The progression of vision loss and onset of weakness in the right leg warranted neuroimaging.

RESULTS

Magnetic resonance imaging documented multiple lesions in the brain and spinal cord.

CONCLUSION

Although rarely reported, progression of optic neuropathy over months has been previously documented in Leber hereditary optic neuropathy. The emergence of multiple sclerosis-like symptoms and signs in our patient may be part of the spectrum of Leber hereditary optic neuropathy or a coincidental occurrence.

Disc excavation in dominant optic atrophy: differentiation from normal tension glaucoma

OBJECTIVE

In patients with dominant optic atrophy (DOA, Kjer type), excavation of the optic nerve develops, and these patients may be misdiagnosed as having normal tension glaucoma (NTG). This study examined disc morphologic features in patients with DOA and explored features that help distinguish this condition from NTG.

DESIGN

Noncomparative, observational case series.

PARTICIPANTS

Patients with DOA who were seen at the Duke University Eye Center between 1987 and 1996 and who had bilateral optic nerve photographs.

METHODS

Retrospective chart review of the results of visual acuity testing, visual field testing by Goldmann perimetry, color vision testing, intraocular pressure measurement, and observation of bilateral optic nerve photographs.

MAIN OUTCOME MEASURES

Appearance of the optic disc and peripapillary zone in patients with DOA.

RESULTS

Nine patients were identified. The mean age at the time of evaluation was 28 years (range, 11-62 years). Most patients had a mild to moderate reduction in visual acuity. Color vision as tested with Hardy-Rand-Rittler plates was reduced (4.0/10 +/- 4.2/10). A cup-to-disc ratio of more than 0.5 was observed in at least one eye of eight patients. A temporal wedge-shaped area of excavation was observed in 14 of the 18 eyes studied. Moderate to severe temporal pallor was observed in all of the eyes. Pallor of the remaining (noncupped) neuroretinal rim was also observed consistently, ranging from mild to moderate. A gray crescent and some degree of peripapillary atrophy were noted in all eyes.

CONCLUSIONS

Several clinical features, including early age of onset, preferential loss of central vision, sparing of the peripheral fields, pallor of the remaining neuroretinal rim, and a family history of unexplained visual loss or optic atrophy, help to distinguish patients with DOA from those with NTG.

Hereditary optic neuropathies

The hereditary optic neuropathies comprise a group of disorders in which the cause of optic nerve dysfunction seems to be heritable as demonstrated or suggested by familial expression or genetic analysis. Clinical variability, both within and among families with the same disease, often makes recognition and classification difficult. Genetic analysis now permits diagnosis of some of the hereditary optic neuropathies in the absence of family history or in the setting of unusual clinical presentations. The hereditary optic neuropathies are classified into three major groups: those that occur primarily without associated neurologic or systemic signs, those that frequently have associated neurologic or systemic signs, and those where the optic neuropathy is secondary in the overall disease process. This article reviewed the different hereditary optic neuropathies and emphasized the most common types.

Magnetization transfer and diffusion tensor MR imaging of the optic radiations and calcarine cortex from patients with Leber's hereditary optic neuropathy

Optic nerve abnormalities are easily detectable in patients with Leber's hereditary optic neuropathy (LHON), using magnetic resonance imaging (MRI). However, the presence of structural changes in the optic radiations and calcarine cortex of these patients is still an unresolved issue. In this study, we obtained magnetization transfer (MT) and diffusion tensor (DT) MRI to investigate the integrity of these structures in patients with LHON. Dual echo, MT- and DT-MRI scans of the brain were obtained from 10 men with LHON and 10 healthy sex- and age-matched controls. After image co-registration, we obtained MT ratio (MTR), average diffusivity (D) and fractional anisotropy (FA) maps. MTR, D and FA values for the white matter of the optic radiations and MTR and D values for the calcarine cortex were obtained using a region of interest (ROI) analysis. No macroscopic abnormalities were detected in any of the scans from LHON patients and controls. No statistically significant differences of MTR, D or FA values were found for any of the regions studied in LHON patients and healthy controls. Our results suggest that, in patients with LHON, the optic radiations and the calcarine cortex are spared from structural damage, both at a macroscopic and a microscopic level.

Four siblings with Hallervorden-Spatz disease

We reported four cases of Hallervorden-Spatz disease. All four siblings (three males and one female) in the family are affected. The first symptoms of the disease were spastic paraparesis and optic atrophy followed by trunkal dystonia and lower motor neurone involvement. The average age of the onset was 4.25 years. The diagnosis was made at the ages of 17, 14, 11 and 10 years. The diagnosis was confirmed clinically, electrophysiologically and by MRI. On MRI scans all patients demonstrated hypointense areas in globus pallidus. There is neither specific treatment nor prenatal diagnosis.

Spectrum, frequency and penetrance of OPA1 mutations in dominant optic atrophy

Dominant optic atrophy (DOA) is the commonest form of inherited optic neuropathy. Although heterogeneous, a major locus has been mapped to chromosome 3q28 and the gene responsible, OPA1, was recently identified. We therefore screened a panel of 35 DOA patients for mutations in OPA1. This revealed 14 novel mutations and a further three known mutations, which together accounted for 20 of the 35 families (57%) included in this study. This more than doubles the number of OPA1 mutations reported in the literature, bringing the total to 25. These are predominantly null mutations generating truncated proteins, strongly suggesting that the mechanism underlying DOA is haploinsufficiency. The mutations are largely family-specific, although a common 4 bp deletion in exon 27 (eight different families) and missense mutations in exons 8 (two families) and 9 (two families) have been identified. Haplotype analysis of individuals with the exon 27 2708del(TTAG) mutation suggests that this is a mutation hotspot and not an ancient mutation, thus excluding a major founder effect at the OPA1 locus. The mutation screening in this study also identified a number of asymptomatic individuals with OPA1 mutations. A re-calculation of the penetrance of this disorder within two of our families indicates figures as low as 43 and 62% associated with the 2708del(TTAG) mutation. If haploinsufficiency is the mechanism underlying DOA it is unlikely that this figure will be mutation-specific, indicating that the penetrance in DOA is much lower than the 98% reported previously. To investigate whether Leber's hereditary optic neuropathy (LHON) could be caused by mutations in OPA1 we also screened a panel of 28 LHON patients who tested negatively for the three major LHON mutations. No mutations were identified in any LHON patients, indicating that DOA and LHON are genetically distinct.

[Genetic diseases of the mitochondrial DNA in humans]

Mitochondrial diseases are a group of disorders produced by defects in the oxidative phosphorylation system (Oxphos system), the final pathway of the mitochondrial energetic metabolism, resulting in a deficiency of the biosynthesis of ATP. Part of the polypeptide subunits involved in the Oxphos system are codified by the mitochondrial DNA. In the last years, mutations in this genetic system have been described and associated to well defined clinical syndromes. The clinical features of these disorders are very heterogeneous affecting, in most cases, to different organs and tissues and their correct diagnosis require precise clinical, morphological, biochemical and genetic data. The peculiar genetic characteristics of the mitochondrial DNA (maternal inheritance, polyplasmia and mitotic segregation) give to these disorders very distinctive properties. The English version of this paper is available at: http://www.insp.mx/salud/index.html.

Acute manifestation of LHON and coincidental finding of a pituitary adenoma: a case report

A patient with Leber Hereditary Opticus Neuropathy (LHON) and a pituitary adenoma is presented. The different ophthalmological signs of LHON are described and illustrated. A definite diagnosis is made by detecting a mitochondrial mutation. A radiological examination revealed a pituitary adenoma. The pituitary adenoma may be a trigger factor in the penetrance of LHON.

The mitochondrial ND6 gene is a hot spot for mutations that cause Leber's hereditary optic neuropathy

Leber's hereditary optic neuropathy (LHON) is a common cause of bilateral optic nerve disease. The majority of LHON patients harbour one of three point mutations of the mitochondrial DNA (mtDNA) complex I, or NADH:ubiquinone oxidoreductase (ND) genes (G11778A in ND4, G3460A in ND1, T14484C in ND6). As a consequence, screening for these mutations has become part of the routine clinical investigation of young adults who present with bilateral optic neuropathy, and the absence of these mutations is interpreted as indicating there is a low likelihood that an optic neuropathy is LHON. However, there are many individuals who develop the clinical features of LHON but who do not harbour one of these primary LHON mutations. We describe two LHON pedigrees that harbour the same novel point mutation within the mtDNA ND6 gene (A14495G). This mutation was heteroplasmic in both families, and sequencing of the mitochondrial genome confirmed that the mutation arose on two independent occasions. This is the seventh mutation in the ND6 gene that causes optic neuropathy, indicating that this gene is a hot spot for LHON mutations. Protein modelling studies indicate that all of these pathogenic mutations lie within close proximity to one another in a hydrophobic cleft or pocket. This is the first evidence for a relationship between a specific disease phenotype and a specific structural domain within a mitochondrial respiratory chain subunit. These findings suggest that the mtDNA ND6 gene should be sequenced in all patients with LHON who do not harbour one of the three common LHON mutations.

Neuro-ophthalmology of mitochondrial diseases

Polymorphism in mitochondrial DNA necessitates careful scrutiny of potentially pathogenic mutations to establish their true pathogenic significance. Research on Leber hereditary optic neuropathy continues to provide insights into the pathogenesis of mitochondrial disease. Interest in the retinal manifestations of mitochondrial disease has highlighted the macular dystrophy of the 3243 mutation, particularly in association with the syndrome of maternally inherited diabetes and deafness. Mitochondrial encephalopathies present in a number of ways, but imaging predominantly shows abnormalities of myelin and grey-matter nuclei. The mitochondrial myopathies provide insights into interactions between nuclear and mitochondrial DNA mutations and parallels between mitochondrial diseases and aging.

False positive molecular diagnosis of Leber's hereditary optic neuropathy

BACKGROUND

The most common pathogenic mitochondrial DNA (mtDNA) mutation associated with Leber's hereditary optic neuropathy (LHON) is at the 11,778 nucleotide (nt) position and is usually detected by loss of an Sfa NI restriction site. However, Sfa NI restriction site includes five nucleotides. Substitution of any of the five nucleotides leads to loss of the cutting site and causes a false-positive result. We investigated the false-positive diagnosis of LHON by loss of the Sfa NI restriction site using Sfa NI restriction site analysis and single-strand conformation polymorphism (SSCP) analysis.

METHODS

Mae III restriction analysis for double confirmation of the Sfa NI restriction site and direct sequencing for final confirmation of SSCP analysis were performed.

RESULTS

The sensitivity of Sfa NI test was 100% and the specificity of the Sfa NI test was 97%. The false-positive rate of Sfa NI test was 3%. SSCP analysis showed 100% sensitivity. Direct sequencing showed 32 patients had a mutation at nt 11,778 of mtDNA and one patient had a silent mutation at nt 11,782 of mtDNA.

CONCLUSIONS

These results suggest that restriction enzyme digestion analysis requires double confirmation to avoid a false-positive diagnosis and that DNA sequencing is needed for the confirmation of the mutation detected by SSCP.

Oval-shaped cornea, lens duplication, and optic nerve hypoplasia associated with myelomeningocele

Oval-shaped cornea associated with true lens duplication and separate capsules is a rare anomaly. It can occur as an isolated finding(1,2) or be associated with other ocular and facial maldevelopments.(3-5) We report a novel association of an hourglass cornea, lens duplication, and optic nerve hypoplasia with myelomeningocele in a male infant.

[Leber optic neuropathy with clinical improvement]

BACKGROUND

Spontaneous recovery in Leber's hereditary optic neuropathy is rare. Does the clinical course of Leber's hereditary optic neuropathy (LHON) differ between patients with and without spontaneous recovery?

MATERIALS AND METHODS

We compared the clinical and molecular genetic characteristics of 12 visually symptomatic patients having the classical clinical course of LHON who recovered spontaneously with those of 60 who did not.

RESULTS

Classical fundus findings and typical visual field defects were comparable in the two groups; vision improved within 18 months in all cases. The worst visual acuity during the acute stage of LHON was 0.03 in the recovery group. Patients with the 3460 and especially the 14484 mutation had a better chance of recovery. No patient with the 11778 mutation who recovered had secondary mutations. Among patients who recovered women were underrepresented and heteroplasmy was more common. Some families showed a raised rate of clinically affected members with recovery.

CONCLUSIONS

The clinical picture of LHON remains the same regardless of whether the patient recovers spontaneously. A higher rate of spontaneous recovery characterizes some families. Spontaneous recovery is rare in women. Heteroplasmy is frequent in patients with recovery. Our results show a better clinical course of LHON in patients with the 11778 mutation without secondary mutations. Prognosis is better if the peripapillary microangiopathy is seen for a relatively long period, and there is only partial optic atrophy.

[A case of Leber's neuroretinitis]

BACKGROUND

Described in 1916 by Theodore Leber, this rare syndrome characterized by low visual acuity, papillary edema, and a macular star (dry exsudates) occurs classically in the 30 to 40 year age range but also as frequently in children. The visual prognosis is excellent. An infectious cause is found in almost all cases. Case report A 34-year-old man consulted for declining visual acuity of the right eye which began suddenly without pain and was preceded by a flu-like syndrome lasting two weeks. Visual acuity on the right side was 2/10 P6, there was optic disk edema associated with dry macular exsudate (macular star) and a paleness of the posterior pole progressing to the periphery and readily visualized on the angiography, and a central scotome, but no dyschromatopsy. The left eye was strictly normal. Laboratory tests showed an erythrocyte sedimentation rate at 45, C reactive protein at 61, normal red cell count and minimal transaminase elevation. Spinal tap showed: 3 elements/mm(3), protein 0.28g/l, 18% gammaglobulins. Serology tests were negative. Brain imaging was normal.

RESULTS

Corticosteroid flashes for three days were initiated and the patient was seen again two weeks later with clear clinical improvement. Visual acuity was 6/10 P2 with considerable resorption of the edema.

DISCUSSION

This case is a typical illustration of acute Leber's neuroretinititis, probably caused by viral infection. The cerebrospinal fluid tests and brain imaging ruled out multiple sclerosis, and serology tests for syphilis, tuberculosis, Lyme disease and possible parasite infection were negative.

CONCLUSION

Acute lever's neuroretinitis is an uncommon condition which must be distinguished from inflammatory optic neuropathy, particularly in multiple sclerosis which has a very different prognosis and clinical course.

Mutational analysis and clinical correlation in Leber congenital amaurosis

Leber congenital amaurosis (LCA, MIM 204001) is a clinically and genetically heterogeneous retinal disorder characterized by severe visual loss from birth, nystagmus, poor pupillary reflexes, retinal pigmentary or atrophic changes, and a markedly diminished electroretinogram (ERG).

PURPOSE

To examine 100 consecutive patients with LCA in order to assess the relative burden of the three known genes involved in LCA, namely retinal guanylyl cyclase (GUCY2D), retinal pigment epithelium protein ( RPE65), and the cone-rod homeobox (CRX), and to define their clinical correlates.

METHODS

Mutational analysis and detailed clinical examinations were performed in patients diagnosed with LCA at the Johns Hopkins Center for Hereditary Eye Diseases and the Montreal Children's Hospital.

RESULTS

Mutations were identified in 11% of our patients: GUCY2D mutations accounted for 6%, while RPE65 and CRX gene mutations accounted for 3% and 2%, respectively. The clinical presentation was variable; however, the visual evolution in patients with mutations in GUCY2D and CRX remained stable, while individuals with mutations in the RPE65 gene showed progressive visual loss.

CONCLUSIONS

This study suggests that molecular diagnosis of Leber congenital amaurosis could provide important information concerning prognosis and course of treatment.

Mutation analysis of 3 genes in patients with Leber congenital amaurosis

OBJECTIVE

To assess the frequency of mutations in the CRX, GUCY2D, and RPE65 genes in patients with Leber congenital amaurosis (LCA).

PATIENTS

One hundred seventy-six probands with a clinical diagnosis of LCA were from 9 countries, with the largest subgroup being 39 probands from India.

METHODS

Samples were screened with single-strand conformation polymorphism analysis followed by DNA sequencing of 3 genes (CRX, GUCY2D, and RPE65) known to be associated with LCA.

RESULTS

Of the 176 probands, 28 (15.9%) harbored possible disease-causing mutations. The relative contribution of each gene to the total number of mutations was as follows: CRX, 2.8%; GUCY2D, 6.3%; and RPE65, 6.8%. No patients who harbored mutations in these genes had associated systemic abnormalities. Molecular diagnosis allowed definitive genetic counseling in a family affected with Best disease and LCA.

CONCLUSIONS

Molecular diagnosis may be of benefit to patients affected with LCA. The relative paucity of mutations found in this study suggests that more LCA-associated genes remain to be discovered.

CLINICAL RELEVANCE

Molecular diagnosis can confirm and clarify the diagnosis of LCA. As genotype data accumulate, clinical phenotypes associated with specific mutations will be established. This will facilitate the counseling of patients on their visual prognosis and the likelihood of associated systemic anomalies.

[A case of Leber optic neuropathy with a new point mutation in the cytochrome b gene]

BACKGROUND

Leber's hereditary optic neuropathy (LHON) is associated with mutations in the mitochondrial DNA (mtDNA). We report the clinical and molecular genetic findings of a patient who does not carry any of the common LHON mutations.

METHODS

Clinical data were collected for the affected patient and two unaffected maternal family members. Complete sequence analysis of the mtDNA protein coding region was performed in the affected patient.

RESULTS

Clinical examination of the affected patient showed typical features of LHON. A nucleotide exchange was detected at np14894 replacing an evolutionarily conserved phenylalanine by a leucine in the cytochrome b gene. The mutation was also present in two unaffected maternal family members, but absent in 60 other LHON lineages and 175 unrelated controls.

CONCLUSIONS

Cytochrome b plays an important role in the electron transport chain of mitochondrial oxidative phosphorylation, and some mutations in the gene encoding cytochrome b have been associated with LHON. Our results may imply that the novel mutation at np14894 is responsible for LHON in this family.

Optic nerve enhancement on magnetic resonance imaging in arteritic ischemic optic neuropathy

Although optic nerve enhancement may be seen in magnetic resonance imaging of radiation-induced ischemic optic neuropathy, similar enhancement in ischemic optic neuropathy has not been previously reported in the English-language neuroophthalmologic literature. We report three cases of optic nerve enhancement in biopsy-proven arteritic ischemic optic neuropathy. Clinicians should consider giant cell arteritis in the differential diagnosis of an optic neuropathy with optic nerve enhancement on magnetic resonance imaging.

Optic nerve enhancement on orbital magnetic resonance imaging in Leber's hereditary optic neuropathy

An 18-year-old man with Leber's hereditary optic neuropathy and bilateral visual loss had optic nerve enhancement on T1-weighted orbital fat-suppressed magnetic resonance imaging. To our knowledge, this is the first reported case of optic nerve enhancement on orbital magnetic resonance imaging in Leber's hereditary optic neuropathy.

[Leber optic neuropathy in women and children]

BACKGROUND

Leber's hereditary optic neuropathy is associated with point mutations in the mitochondrial DNA (mtDNA) that appear to be pathogenetic for this disease. These mutations affect nucleotide positions 3460, 11778 and 14484. Does the clinical course of LHON differ between men, women and children?

MATERIALS AND METHODS

We reviewed the clinical and molecular genetic characteristics of 15 visually symptomatic patients with the clinical diagnosis of LHON (11 women and 4 male children) and compared them with 66 men with LHON.

RESULTS

LHON was confirmed clinically and with molecular genetic methods in all cases. Men, women and children showed no differences: Classic fundus findings and typical visual field defects were equally found in both sexes. However, age at the beginning of the disease, severity of LHON and rate of spontaneous recovery differed between groups. Women were older (19-55 years, average 31.3 years) than men (15-53 years, average 24.3 years) at the beginning of the disease. Women suffered more severely from LHON. Spontaneous recovery of vision in women was extremely rare. Many more women had a LHON-affected mother than men. All the affected children (9-14, average 11.7 years at the beginning of the disease) did not have a good visual outcome.

CONCLUSIONS

There are some differences in the course of LHON between men and women, concerning age, severity of LHON and rate of spontaneous recovery. Children may also have an unfavorable prognosis.

[Leber's hereditary optic nerve neuropathy]

The authors present a case report of 26 years old man with bilateral optic nerve neuropathy. Detection of heteroplasmic mutation of mitochondrial DNA at G3460A site confirmed the suspicion on Lebers hereditary optic nerve neuropathy (LHON). Genetic and environmental factors of the disease and various accompanying neurologic and other symptoms, which can together with the optic nerve defect participate in the development of of the LOHN clinical pattern are discussed. (Ref. 12.)

Leber's hereditary optic neuropathy

A case of Leber's hereditary optic neuropathy (LHON) in a healthy young man who presented with a slow progressive visual loss in one eye and later developed a visual loss in the other eye. There was no pre-existing symptom and no history of visual loss in other family members. Mitochondrial DNA mutation at 11,778 was found in the patient and his uneffected mother and brother. Currently the availability of reliable molecular genetic testing has revolutionized the diagnosis of LHON. LHON is a maternal inherited disorder that causes bilateral visual loss, predominantly in young men. This disorder has been associated with point mutations in the mitochondrial genome which constitute the different clinical phenotypes and prognosis. Genetic counseling in families at risk is recommended.

Ocular and oculomotor signs in Joubert syndrome

A number of oculomotor defects have been described in Joubert syndrome. This study systematically examined the oculomotor systems of 13 individuals previously diagnosed with Joubert syndrome. Twelve had the characteristic "molar tooth sign" seen on magnetic resonance imaging scan. In all individuals, smooth pursuit gain and vestibulo-ocular reflex cancellation were decreased in the horizontal and vertical directions and volitional saccades, when generated, were hypometric. We believe that these defects arise from a disorder in the posterior cerebellar vermis. All individuals also had partial to complete oculomotor apraxia in which initiation of saccades was prolonged or impaired. The oculomotor apraxia in Joubert syndrome differs from congenital idiopathic oculomotor apraxia in that both volitional saccades and quick phases of nystagmus were impaired both in the horizontal and vertical directions, and the defects did not resolve with time. We believe that the oculomotor apraxia arises from a disorder involving the projections from the superior colliculus to the parapontine reticular formation and rostral interstitial nucleus of the medial longitudinal fasciculus. A subset of individuals also had severe visual loss, pendular nystagmus, pigmentary changes in the fundus, and decreased vestibulo-ocular reflexes. We believe that this is a form of Leber's amaurosis occasionally associated with Joubert syndrome. In summary, key oculomotor features of Joubert syndrome are decreased smooth pursuit and vestibulo-ocular reflex cancellation, partial to complete oculomotor apraxia both in the horizontal and vertical directions, and hypometric saccades if oculomotor apraxia is not complete.

[Clinical manifestation and molecular identification of patients with Leber's hereditary optic neuropathy in a national reference center for neuro-ophthalmology in Cuba]

INTRODUCTION

Leber's hereditary optic neuropathy (LHON) is a mitochondrial disorder, confirmed at a molecular level 10 years ago. This had permitted better understanding of the condition. Since 1998, the Instituto de Neurología y Neurocirugía has used these techniques for the study of mutations which are considered to be the origin of the disorder.

PATIENTS AND METHODS

We describe the characteristics of 14 cases from 10 families with LHON and the molecular confirmation found between 1994 and 1998 in the Instituto de Neurología Neurocirugía de Cuba. We also review the few cases seen in the previous 18 years. These were from only two families. They were diagnosed on clinical grounds and in view of maternal inheritance.

RESULTS AND CONCLUSIONS

In 80% of the families in which the presence of primary mutations was investigated there was A117789, and in 20% A3460G. The average age of appearance was 28 years. The ages of onset were within the limits of 11 years and 48 years. There were 43% women. Two cases were considered to be sporadic. The clinical features corresponded to those described in such cases, with severe visual defects, central scotomas, very reduced colour vision and severely altered visual evoked potentials, with normal diffuse light and pattern electroretinograms. An improvement in visual acuity of 0.2 was seen in two cases. Microangiopathy, described as characteristic of the early stages of this disorder was detected in five cases, in at least one eye. The others had different degrees of optic atrophy. Two generations of one complete family, all with mutation 3460, were studied. In several families with this mutation alterations were found in the colour vision test of Farnsworth Munsell Hue 100 and also microangiospathy of the retina.

Update on hereditary optic neuropathy

Although no treatment is available for hereditary optic neuropathies, recent localization and identification of some of the genetic loci have helped the evaluation and management of patients with these disorders. This article discusses the clinical features and known genetic information regarding Leber's hereditary optic neuropathy, dominant optic atrophy, recessive optic atrophy, and Wolfram syndrome.

Leber's hereditary optic neuropathy mitochondrial DNA mutations in familial multiple sclerosis

Leber's hereditary optic neuropathy (LHON) can be difficult to distinguish from optic neuritis due to multiple sclerosis (MS). For several decades an association of LHON and MS has been suspected, and within the past 7 years the LHON nucleotide (nt)-3460 and nt-11778 mtDNA mutations have been identified in several patients with MS-like phenotypes. To further study this association, we tested 42 index patients with clinically definite, familial MS for the LHON mtDNA mutations at nt-3460, nt-11778, and nt-14484. No patients had a pathogenic LHON mtDNA mutation; however, two MS patients with unilateral optic neuritis harbored the nt-15257 mtDNA polymorphism that was reported originally as a pathogenic LHON mutation. Several investigators have shown evidence that the nt-15257 mtDNA mutation is not primarily pathogenic. Therefore, we conclude that pathogenic LHON mtDNA mutations are absent or rare in unselected patients with familial, clinically definite MS (95% confidence intervals for each of the negative mutations 0-7.0%).

[An analysis of 6 Leber mutations in 31 individuals with optic atrophy. A study of its transmission in 5 families]

BACKGROUND

Leber's hereditary optic neuropathy (LHON) is a mitochondrial disorder that represents the most frequent cause of visual loss among otherwise healthy young men.

PATIENTS AND METHODS

We have screened for the most important LHON mutations (primary mutations) and several other previously described mutations (secondary mutations) in 31 Spanish patients suffering from optic atrophy. These individuals fulfilled the clinical criteria for LHON. We have compared the mutation frequencies obtained with those reported in several other countries. We have also followed the segregation of the disease and its associated LHON mutations in five families. The screening has been performed by PCR followed by restriction enzyme digestions and electrophoretic separation.

RESULTS

67.75% of the patients did not harbour any of the studied mutations, whereas 16.13% showed one mutation and the remaining 16.13% carried two Leber mutations in their mitochondrial DNA. The three primary mutations as well as G15257A were the changes most frequently detected (30% each of them). There were no significant differences among the compared populations in terms of frequencies of the primary mutations. In contrast, our patients showed a significantly higher rate of 15257 mutation.

CONCLUSIONS

The incidence of primary LHON mutations among the Spanish patients is not statistically different from those observed in other Caucasian populations. Transmission of the mutation to the progeny is not necessarily linked to the transmission of the disease. This fact complicates genetic counselling and makes prenatal diagnosis almost impossible for this disease.

A multiple sclerosis-like illness in a man harboring the mtDNA 14484 mutation

In most cases of Leber's hereditary optic neuropathy (LHON) the only clinical manifestation is visual loss. A multiple sclerosis-like illness has been infrequently reported in association with LHON. Most patients are women harboring the mtDNA 11778 mutation. We present a young man with clinical and paraclinical evidence of a demyelinating process with profound bilateral visual loss who harbored the mtDNA 14484 mutation associated with LHON.

Dominant optic atrophy. Refining the clinical diagnostic criteria in light of genetic linkage studies

OBJECTIVE

To describe the clinical findings and refine the clinical diagnostic criteria for dominant optic atrophy based on eight British families in which the diagnosis was confirmed by linkage analysis.

DESIGN AND PARTICIPANTS

Case series; 92 subjects in 8 pedigrees had both eyes examined.

INTERVENTION

Family members received a domiciliary examination based on best-corrected visual acuity, color vision using Ishihara and Hardy Richter Rand (HRR) plates, confrontation field testing using a red target, and optic disc evaluation using a direct ophthalmoscope. Genomic DNA was extracted from leukocytes or buccal mucosal cells and genotyped using 12 fluorescently labeled microsatellite markers from the region 3q27-q29.

MAIN OUTCOME MEASURES

Subjects were classified clinically as definitely or possibly affected on the basis of the domiciliary examination before genetic analysis, and these results were compared with the haplotype analysis.

RESULTS

Clinically, 43 subjects were identified as definitely affected, 4 as possibly affected, and 45 as unaffected. Visual acuity in affected subjects ranged from 6/6 to count fingers and declined with age. On genetic analysis, a haplotype was identified in each family, which was found in all definitely affected members but not in those regarded as unaffected. The four possibly affected individuals also bore the haplotype that segregated with the disease.

CONCLUSIONS

Simple clinical tests are highly efficacious in diagnosing dominant optic atrophy. Contrary to accepted criteria, symptoms begin before the age of 10 years in only 58% of affected individuals. Visual acuity in affected subjects is highly variable. A mild degree of temporal or diffuse pallor of the optic disc and minimal color vision defects, in the context of a family with dominant optic atrophy, are highly suggestive of an individual being affected, even if the visual acuity is normal. This widens the generally accepted diagnostic criteria for this disease.