Gena Heidary

Identification and characterization of the Drosophila tau homolog.

A pathological hallmark of neurodegenerative tauopathies, including Alzheimers disease and a group of clinically heterogeneous frontotemporal dementias, is the presence of intracellular neurofibrillary protein lesions (reviewed in Spillantini and Goedert, TINS 10 (1998) 428). The principal component of these structures is the microtubule-associated protein tau. Although tau is normally a highly soluble protein enriched in axons, in these deposits, it is abnormally hyperphosphorylated, insoluble, and redistributed to the somatodendritic compartments of neurons. Through ultrastructual analyses, it has been determined that the tau protein in these lesions is filamentous and organized into paired-helical filaments, straight filaments, or ribbon-like filaments (Goedert et al., The Molecular and Genetic Basis of Neurological Disease (1997) 613). By the dynamic binding of microtubules, tau is thought to promote the structural stability of axons, but whether tau aggregates contribute to neurodegeneration through a direct toxicity on normal cellular functions such as organelle transport or an indirect effect on microtubule stability, is currently unknown. The identification of mutations in the tau locus in patients with familial frontotemporal dementia and Parkinsonism linked to chromosome 17 has demonstrated that mutations in tau are sufficient to cause neurodegenerative disease (Poorkaj et al., Ann. Neurol. 43 (1998) 815; Hutton et al., Nature 393 (1998) 702). To elucidate the mechanisms by which tau dysfunction contributes to neuronal loss, we have sought to model human tauopathies in a genetically tractable organism. Here we describe the isolation of a Drosophila tau cDNA (GenBank accession number AY032977), the production of antibodies that recognize the encoded protein, and their use in determining the expression and subcellular localization of the fly tau protein.

Retinopathy of Prematurity: Current Concepts in Molecular Pathogenesis

Retinopathy of prematurity is marked by the proliferative vascularization of the retina in preterm babies. An understanding of the molecular pathogenesis of ROP provides the basis for identifying novel therapeutic targets for treatment. Using the mouse model of oxygen-induced retinopathy, the roles of the hypoxia induced factors vascular endothelial growth factor and erythropoietin as well as the maternally derived factors insulin-like growth factor-1 and omega-3 polyunsaturated fatty acids have begun to be elucidated. Understanding the phase specific effects of these factors will serve to guide the development of non destructive treatments for ROP and for other ischemic retinopathies including diabetic retinopathy and neovascular age-related macular degeneration.

Congenital Fibrosis of the Extraocular Muscles

Congenital fibrosis of the extraocular muscles (CFEOM) is a strabismus syndrome characterized by non-progressive, restrictive ophthalmoplegia of the extraocular muscles and congenital blepharoptosis. Three clinical phenotypes for familial CFEOM (CFEOM1, 2, and 3) have been delineated, for which two genes have been identified to date: KIF21A for CFEOM1 and 3 and PHOX2A/ARIX for CFEOM2. Insights gained from molecular genetics have strengthened the hypothesis that CFEOM results from the dysinnervation of the extraocular muscles supplied by the oculomotor and/or trochlear nerves. Continued study of this syndrome should help to further elucidate the pathogenesis of eye movement disorders.

Use of Optical Coherence Tomography to Evaluate Papilledema and Pseudopapilledema

Idiopathic intracranial hypertension (IIH), or pseudotumor cerebri, describes a condition of elevated intracranial pressure (ICP) that typically presents in obese women of childbearing age with symptoms and signs of posture-dependent headaches, pulsatile tinnitus, visual changes, and papilledema. Optical coherence tomography (OCT) has begun to be utilized as an adjunctive, quantitative tool in the evaluation of patients with IIH to help distinguish between true optic nerve head edema and pseudopapilledema, and to contribute to our understanding of the consequences of prolonged optic nerve edema. Although few longitudinal studies of patients with IIH have been published to date, it appears that there may be a correlation between retinal nerve fiber layer (RNFL) thickness and visual function. With the new spectral domain OCT, additional parameters of the optic nerve imaging, including volume and height measurements, might provide greater sensitivity of the response to treatment and the long-term visual outcome in patients with IIH.

Exclusion of the gastrin-releasing peptide receptor (GRPR) locus as a candidate gene for Rett syndrome.

The gene for the gastrin-releasing peptide receptor (GRPR) has been mapped to a candidate region for Rett syndrome (RTT) on the short arm of the X chromosome. The recent report of a translocation that disrupted the gene in an individual with mental retardation and autistic behavior prompted us to examine GRPR as a possible locus for RTT. Genomic polymerase chain reaction amplification of exons followed by single-strand conformation analysis screening in 25 unrelated RTT-affected individuals and by direct sequencing in 12 others has failed to detect any mutation. No gross structural rearrangements were found by Southern analysis of DNA from six unrelated RTT-affected individuals. A high-frequency biallelic polymorphism caused by two single nucleotide substitutions in exon 2 was discovered. The allele frequencies were identical in the RTT population as compared to 100 normal control X chromosomes. This polymorphism will enable future evaluation of the GRPR locus as a candidate for other X-linked mental retardation or neurobehavioral syndromes.

Optic atrophy and a Leigh-like syndrome due to mutations in the c12orf65 gene: report of a novel mutation and review of the literature.

Combined oxidative phosphorylation deficiency type 7 (COXPD7) is a rare disorder of mitochondrial metabolism that results in optic atrophy and Leigh syndrome-like disease. We describe 2 siblings with compound heterozygous mutations in the recently identified C12orf65 gene who presented with optic atrophy and mild developmental delays and subsequently developed bilateral, symmetric lesions in the brainstem reminiscent of Leigh syndrome. Repeat neuroimaging demonstrated reversibility of the findings in 1 sibling and persistent metabolic stroke in the other. This article highlights the phenotypic manifestations from a novel mutation in the C12orf65 gene and reviews the clinical presentation of the 5 other individuals reported to date who carry mutations in this gene.

Visual Outcomes in Pediatric Optic Neuritis

PURPOSE To describe the visual outcomes of a large cohort of pediatric patients presenting to a tertiary care pediatric hospital with first-episode optic neuritis. DESIGN Retrospective, observational cohort study. METHODS In a tertiary care pediatric hospital, patients with first-episode optic neuritis and at least 3 months of follow-up over a 10-year period were assessed and followed-up in the ophthalmology department. The main outcome measures were visual acuity at 3 months and 1 year of follow-up, with analysis of risk factors for poor visual outcomes and the time course of visual recovery. RESULTS Of the 59 pediatric patients with first-episode optic neuritis, 46 had at least 3 months of follow-up and 36 had at least 1 year of follow-up. The mean age was 12.6 years old; 72% were female, 41% had bilateral involvement, 52% had or developed an underlying diagnosis (39% multiple sclerosis, 7% acute disseminated encephalomyelitis, 7% neuromyelitis optica), and 91% received treatment (85% steroids, 7% multimodal). At 1 year, 81% were at least 20/20 and 89% were at least 20/40. A poor visual outcome at 1 year (<20/40) was associated with vision of <20/20 at 3 months (P = 0.041). Other clinical characteristics, including visual acuity at presentation, sex, bilateral involvement, optic nerve edema, and underlying diagnoses were not significantly associated with poor visual outcomes. CONCLUSIONS In this cohort of pediatric patients with optic neuritis, the majority of patients regained normal visual acuity at 1 year, regardless of baseline clinical characteristics.

Relationship between the timing of cataract surgery and development of nystagmus in patients with bilateral infantile cataracts

PURPOSE To study the relationship between timing of surgery as a risk factor for the development of manifest nystagmus in patients with bilateral infantile cataracts and to determine the effect of nystagmus on visual outcomes. METHODS The medical records of patients with bilateral infantile cataracts operated on before 12 months of age between January 1991 and December 2009 were retrospectively reviewed. Patients were stratified into two groups: early (age <8 weeks) or late (age >8 weeks) surgery. RESULTS A total of 56 patients (29 males) were studied. Early surgery was performed in 26 patients. Of these, 10 (38%) had manifest nystagmus at the most recent follow-up. Of 30 patients who underwent late surgery, 15 (50%) had manifest nystagmus at the most recent follow-up. There was not a statistically significant impact on the timing of cataract surgery and the development of postoperative nystagmus (P = 0.43). In total, 25 of 56 (45%) patients had postoperative manifest nystagmus; in these patients, there was a statistically significant decrement in final logMAR visual outcomes compared with those patients without postoperative nystagmus (0.26 vs 0.16; P = 0.04); however, preoperative nystagmus did not appear to be a risk factor for a worse visual outcome. CONCLUSIONS Manifest nystagmus is a common feature in children with bilateral infantile cataracts, regardless of the timing of surgery. Early surgery as defined in this study does not necessarily prevent its development. Postoperative nystagmus is more common when surgery is performed later but can improve as the child matures.

Morning Glory Disc Anomaly: Characteristic MR Imaging Findings

SUMMARY: Establishing the diagnosis of morning glory disc anomaly is crucial to appropriate patient treatment. Although typically made clinically, the diagnosis is not always straightforward, especially in circumstances where physical examination is limited. The goal of this study was to define the spectrum and frequency of orbital findings in a series of patients with funduscopically-confirmed morning glory disc anomaly by using MR imaging. MR imaging demonstrated 3 findings in all patients: 1) funnel-shaped morphologic pattern of the posterior optic disc with elevation of the adjacent retinal surface; 2) abnormal tissue associated with the distal intraorbital segment of the ipsilateral optic nerve, with effacement of the regional subarachnoid spaces; and 3) discontinuity of the uveoscleral coat. These findings were not observed in any of the unaffected globes of the study patients. In summary, these consistent and characteristic findings of morning glory disc anomaly should allow for accurate differentiation from other ocular anomalies and have the potential to guide appropriate management of this patient population.

Using spectral-domain optical coherence tomography to detect optic neuropathy in patients with craniosynostosis

BACKGROUND Detecting and monitoring optic neuropathy in patients with craniosynostosis is a clinical challenge due to limited cooperation, and subjective measures of visual function. The purpose of this study was to appraise the correlation of peripapillary retinal nerve fiber layer (RNFL) thickness measured by spectral-domain ocular coherence tomography (SD-OCT) with indication of optic neuropathy based on fundus examination. METHODS The medical records of all patients with craniosynostosis presenting for ophthalmic evaluation during 2013 were retrospectively reviewed. The following data were abstracted from the record: diagnosis, historical evidence of elevated intracranial pressure, current ophthalmic evaluation and visual field results, and current peripapillary RNFL thickness. RESULTS A total of 54 patients were included (mean age, 10.6 years [range, 2.4-33.8 years]). Thirteen (24%) had evidence of optic neuropathy based on current fundus examination. Of these, 10 (77%) demonstrated either peripapillary RNFL elevation and papilledema or depression with optic atrophy. Sensitivity for detecting optic atrophy was 88%; for papilledema, 60%; and for either form of optic neuropathy, 77%. Specificity was 94%, 90%, and 83%, respectively. Kappa agreement was substantial for optic atrophy (κ = 0.73) and moderate for papilledema (κ = 0.39) and for either form of optic neuropathy (κ = 0.54). Logistic regression indicated that peripapillary RNFL thickness was predictive of optic neuropathy (P < 0.001). Multivariable analysis demonstrated that RNFL thickness measurements were more sensitive at detecting optic neuropathy than visual field testing (likelihood ratio = 10.02; P = 0.002). Sensitivity and specificity of logMAR visual acuity in detecting optic neuropathy were 15% and 95%, respectively. CONCLUSIONS Peripapillary RNFL thickness measured by SD-OCT provides adjunctive evidence for identifying optic neuropathy in patients with craniosynostosis and appears more sensitive at detecting optic atrophy than papilledema.