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Bardet−Biedl Syndrome
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Among the primary (cardinal) features of BBS, retinal degeneration includes rod-cone dystrophy, choroidal dystrophy, and global severe retinal dystrophy, of which rod-cone dystrophy (also referred to as retinitis pigmentosa due to defects in the transport of phototransduction proteins from the inner to the outer segments of photoreceptors causing rod and cone cell death) is most common, affecting 90%–100% of patients. Rod-cone dystrophy is a progressive retinal degeneration that usually manifests as night blindness by age 7 or 8, loss of color discrimination, and progressive tunnel vision (lose of peripheral vision) by the first decade of life, then loss of central vision and legal blindness by the second or third decade of life (Figure 25.1) [21–23]. Additional ophthalmologic features consist of nystagmus (rapid, involuntary eye movements), strabismus (lazy eye), high myopia, cataract (clouding of the lens), and glaucoma (damage to the optic nerve conducting signals to the brain).
Genetics
Published in Stephan Strobel, Lewis Spitz, Stephen D. Marks, Great Ormond Street Handbook of Paediatrics, 2019
Jane A. Hurst, Richard H. Scott
Initial presentation is with pre- or early postnatal detection of structural physical abnormalities such as postaxial polydactyly (Fig. 15.45) or cystic kidney disease. Truncal obesity is present in approximately 70% and usually develops during the first year (Fig. 15.46). Progressive rod–cone dystrophy causes night blindness by 8 years. The mean age of registered visual loss is 15–16 years. Renal disease is also progressive and end-stage kidney disease is present in 10% of patients. Diabetes mellitus and abnormal lipid profiles are also features.
Clinical Manifestation of Mitochondrial Disorders in Childhood
Published in Shamim I. Ahmad, Handbook of Mitochondrial Dysfunction, 2019
PEO has traditionally featured with ptosis and paralysis of the extraocular muscles (ophthalmoplegia). Some patients with PEO may have particular manifestations of KSS but do not fulfil all the clinical criteria for the diagnosis. Such a situation is termed “KSS minus” or “PEO plus.” Kearns-Sayre syndrome (Kearns and Sayre, 1958) manifests with PEO, typical onset before age 20 years, pigmentary retinopathy, and cardiac conduction block or hyperproteinorhachia or ataxia. Other frequently present clinical features include cerebellar ataxia, cardiac conduction defects with conduction block, raised cerebrospinal fluid protein content, and proximal myopathy. Proximal or distal tubular acidosis may occur. If the patient survives into the fourth decade of life, bilateral sensorineural hearing loss is typical. Patients may more rarely manifest also with deafness, limb-girdle myopathy, multiple endocrinopathies and diabetes mellitus (about 13% of patients) (Harvey and Barnett, 1992), and dementia. Hypoparathyroidism and Addison disease may also be present (Berio and Piazzi, 2013). Funduscopy reveals an atypical “salt and pepper” retinopathy caused by rod-cone dystrophy. Retinal dystrophy is present in ERG, with normal visual fields. More than half of KSS patients have cardiac involvement, including recurrent syncope, bundle branch blocks, fascicular blocks and non-specific intraventricular conduction disturbance. Cardiac causes contribute to about 20% of deaths of KSS patients (Charles et al., 1981). The histopathological diagnosis of KSS is usually based on the presence of ragged red fibres with positive succinate dehydrogenase staining.
Expanding the clinical phenotype in patients with disease causing variants associated with atypical Usher syndrome
Published in Ophthalmic Genetics, 2021
Austin D. Igelman, Cristy Ku, Mariana Matioli da Palma, Michalis Georgiou, Elena R. Schiff, Byron L. Lam, Eeva-Marja Sankila, Jeeyun Ahn, Lindsey Pyers, Ajoy Vincent, Juliana Maria Ferraz Sallum, Wadih M. Zein, Jin Kyun Oh, Ramiro S. Maldonado, Joseph Ryu, Stephen H. Tsang, Michael B. Gorin, Andrew R. Webster, Michel Michaelides, Paul Yang, Mark E. Pennesi
The age of onset of the six patients with ABHD12 disease ranged from 16 years to early the 30s . Four presented with central blurring. None reported vestibular dysfunction and three had progressive SNHL with an age of onset ranging from 20 to 44 years. Of the four patients with longitudinal BCVA data, all but one (ABHD12-2) had progressive worsening. Four patients had BCVA of 20/200 or worse in both eyes. While these patients had severely decreased BCVA at an early age, ABHD12-1 showed 20/25 BCVA at age 48 years. ffERG was obtained on four patients; three (ABHD12-2, ABHD12-3, ABHD12-4) were suggestive of rod-cone dystrophy and one (ABHD12-1) was undetectable for both rods and cones. All three patients with a rod-cone dystrophy had mild cone dysfunction but rod dysfunction included mild (ABHD12-3), moderate (ABHD12-4), and severe (ABHD12-2). KVF was obtained only on ABHD12-1 and showed constricted visual fields to 50 degrees with a central scotoma of 10 degrees along the horizontal meridian to a V 4e target.
Resolution of cystoid macular edema with topical carbonic anhydrase inhibitor in a patient with retinal dystrophy associated with Cohen syndrome
Published in Ophthalmic Genetics, 2021
Mehmet Orkun Sevik, Aslan Aykut, Özlem Şahin
Clinical correlation with genotype in CS is still not established (2). Our patient is the second CS patient in the literature with homozygous c.62 T > G, p.(Leu21*) mutation in the VPS13B gene, and like our case, the previously reported patient by Koehler et al. also had macular cystoid changes in OCT (12). Although retinal pigmentary changes in CS patients as early as nine-months-old with other mutations have been reported (2,6–8), our patient’s dilated fundus examination revealed only barely visible macular pigmentation, slightly attenuated retinal vessels, and mild optic disc pallor without any peripheral pigmentary changes. Still, ERG showed rod-cone dystrophy, emphasizing its importance in diagnosing retinal dystrophy in a CS patient without noticeable retinal changes. Similarly, Koehler et al. reported mild optic atrophy without retinal pigmentary changes but a progressive narrowing of arteries in the retrospective analysis of fundus photographs of their 19-year-old patient with the same mutation as our case (12). Therefore, we believe that there might be a clinical correlation with genotype yet to be determined in terms of retinal involvement in CS. Koehler et al. (12) did not report FA findings of their case in their report, and we could not perform a FA because of a lack of informed consent. So, based on our experience and published literature, whether CME associated with CS resulted from homozygous c.62 T > G, p.(Leu21*) mutation leaks on FA or not can not be determined.
Novel mutation in SLC4A7 gene causing autosomal recessive progressive rod-cone dystrophy
Published in Ophthalmic Genetics, 2020
Jeeyun Ahn, John Chiang, Michael B. Gorin
Most of the genes identified encode proteins that have essential roles in the phototransduction cascade, visual cycle, ciliary structure and transport, and the maintenance of retinal homeostasis (2). Identifying the genes and the affected pathways in rod-cone dystrophy have not only allowed clinicians to understand the underlying pathogenesis behind this subtype of IRD but also given insight into the complex molecular pathways involved in the various interactions between photoreceptors and the RPE and the maintenance of these cells within the retina. Recent advances in genetic analysis techniques have enabled the applications of panel-based targeted sequencing and exome sequencing in identifying novel genetic causes resulting in overall improvement diagnostic yield (3,4). In this case report, we present a rod-cone dystrophy patient with a mutation in SLC4A7, adding to the list of previous solute carrier genes implicated in retinal disorders (SLC24A1, SLC7A14, SLC25A46) (5).