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The eye
Published in Angus Clarke, Alex Murray, Julian Sampson, Harper's Practical Genetic Counselling, 2019
Numerous types of corneal dystrophy exist. The slit-lamp appearance is often very characteristic (to the expert), and unless a clear pedigree pattern is seen, it is wise to be guided by ophthalmological opinion. Most types are Mendelian. Corneal clouding and opacification may be a helpful diagnostic feature in various generalised diseases, notably the mucopolysaccharidoses (including Fabry disease in females) and mucolipidoses, but also in some lipoprotein disorders, Zellweger syndrome and cystinosis.
Cornea
Published in Mostafa Khalil, Omar Kouli, The Duke Elder Exam of Ophthalmology, 2019
Mostafa Khalil, Omar Kouli, Rizwan Malik
The most common corneal dystrophy. Inheritance is sporadic or AD. It is more common in elderly females. It is due to a failure of the Na+K+ pump leading to accumulation of fluid in the cornea which leads to endothelial cell loss.
Special Senses
Published in Pritam S. Sahota, James A. Popp, Jerry F. Hardisty, Chirukandath Gopinath, Page R. Bouchard, Toxicologic Pathology, 2018
Kenneth A. Schafer, Oliver C. Turner, Richard A. Altschuler
Corneal deposits often consist of mineral. Some deposits are a feature of corneal dystrophy, but others may be due to other causes (Peiffer et al. 1994; Taradach et al. 1981). Corneal dystrophy is a spontaneous, noninflammatory, bilateral corneal change that occurs in several laboratory animals (Moore et al. 1987; Port and Dodd 1983; Shibuya et al. 2001). Microscopically, the finding consists of mineralized deposits along the corneal epithelial basement membrane (Bruner et al. 1992; Carlton and Render 1991a; Hoffman et al. 1983; Losco and Troup 1988). A high spontaneous incidence of corneal mineralization has been reported in Wistar Hannover rats, being greater in males compared to females, with a hypothesis proposed that in response to mineralization, keratocytes become active to play an important role in responding to the mineralized substance (Hashimoto et al. 2013). Mineralized deposits in the cornea adjacent to the palpebral fissure are referred to clinically as band keratopathy.
Unilateral posterior polymorphous corneal dystrophy due to a novel ZEB1 gene mutation in a Korean girl
Published in Ophthalmic Genetics, 2022
Chae Yeon Lee, Ja-Hyun Jang, Gyule Han, Tae-Young Chung, Dong Hui Lim
The child in this case report revealed a likely pathogenic variant in the ZEB1 gene and her clinical manifestation was consistent with PPCD3. In 2010, Nguyen et al. reported a novel change in exon 5 of ZEB1 (c.672delA) that resulted in clinical phenotype in a family with PPCD (6,7). Since then, many studies on ZEB1 have been conducted. ZEB1 is thought to be responsible for up to 50% of PPCD cases (7,8). Although the exact mechanism which induces corneal dystrophy is not fully elucidated, ZEB1 binds to a promoter of the COL4A3 gene and, when ZEB1 is mutated, the expression of the COL4A3 protein is altered, which may provoke the endothelial cells to manifest a different phenotype. Furthermore, the ZEB1 protein has been implicated in many other metabolic pathways, including epithelial–mesenchymal transition (9). There has been retrocorneal membrane growth observed when interventions like surgery or trauma were performed in patients with this gene mutation and the frequency of guttata expression was higher. In addition to corneal disease, an association with metabolic diseases such as obesity or inguinal hernia has also been reported (10).
Assessment of incorporation of the International Committee for Classification of Corneal Dystrophies (IC3D) in literature
Published in Ophthalmic Genetics, 2020
Saif Aldeen AlRyalat, Bahaa Al-Din Jaber
The present study sheds a light on the adoption of the recently issued nomenclature for corneal dystrophy, which has important clinical and practical implications. Most dystrophies have multiple names and eponyms that are used in the literature, some of which may be misleading, and naming Schnyder corneal dystrophy as a “crystalline” dystrophy is an example. The adoption of this change was well implemented in the literature, as 80.95% of publications used the new name “Schnyder corneal dystrophy”. This change in nomenclature emphasized on the possibility of diagnosing this dystrophy without the presence of crystals (5). On the other hand, granular corneal dystrophy type 2 was the least used among the approved nomenclature, as Avellino dystrophy alone was used in almost half of the publications. The main limitation of the current study is that cases of corneal dystrophy may be published in languages other than English, which were not covered in the current study.
Phototherapeutic Keratectomy in Macular and Granular Dystrophy: Two-year Results
Published in Seminars in Ophthalmology, 2020
Burcu Kemer Atik, Yusuf Yildirim, Orcun Sonmez, Gulsah Gumus, Burcin Kepez Yildiz, Alper Agca
Corneal dystrophies are a group of diseases with bilateral, progressive, non-inflammatory, and genetic transmission.1–3 Granular and macular corneal dystrophies are in the group of stromal corneal dystrophies and are characterized by corneal opacification.1,2 Granular corneal dystrophy is characterized by amorphous hyaline deposits in the stromal layer of the cornea, and shows autosomal dominant inheritance.1,4 Macular corneal dystrophy shows autosomal recessive genetic transition, and abnormal proteoglycan synthesis is the main mechanism in its pathogenesis.1,2,4 In both granular and macular dystrophy, abnormal corneal deposits diminish corneal transparency and this leads to decreased visual acuity. Penetrating keratoplasty, deep anterior lamellar keratoplasty, or phototherapeutic keratectomy (PTK) may be preferred in the treatment of corneal opacifications.1–4