Macular Dystrophy, Corneal (MCD)

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OMIM 57 217800 Disease Ontology 12 DOID:2565 ICD10 33 H18.55 ICD9CM 35 371.55 MeSH 44 D003317 NCIt 50 C34793 SNOMED-CT 68 60258001

Orphanet 59 ORPHA98969 UMLS via Orphanet 74 C1636149 C0024439 ICD10 via Orphanet 34 H18.5 MedGen 42 C1636149 C1691013 KEGG 37 H00954 SNOMED-CT via HPO 69 258211005 2055003 91514001 246622003 409668002 5587004 more UMLS 73 C0024439 C1636149 C1691013

NIH Rare Diseases : ⁵³ The following summary is from Orphanet, a European reference portal for information on rare diseases and orphan drugs.Orpha Number: 98969Disease definitionMacular corneal dystrophy (MCD) is a rare, severe form of stromal corneal dystrophy (see this term) characterized by bilateral ill-defined cloudy regions within a hazy stroma, and eventually severe visual impairment.EpidemiologyPrevalence of this form of corneal dystrophy is not known. Cases of MCD have been identified worldwide. The condition is most prevalent in India, Saudi Arabia, Iceland and parts of the USA.Clinical descriptionWhitish opacities in the cornea usually appear during adolescence but may develop in early infancy, or as late as the 6th decade of life. The non-transparent areas progressively merge as the entire corneal stroma becomes cloudy, causing severe visual impairment usually before the 5th decade. The bilateral corneal opacities progressively extend through the entire thickness of the central and peripheral corneal stroma. The corneal stroma is thinner than normal.EtiologyMost cases of MCD are caused by mutations in the CHST6 gene (16q22) encoding a protein involved in the production of keratan sulfate, which plays a role in the maintenance of corneal transparency. More than 125 mutations in this gene have been identified to date.Diagnostic methodsMCD is characterized histopathologically by intracytoplasmic accumulations of non-sulfated keratan sulfate within the keratocytes and corneal endothelium, sparing the corneal epithelium. MCD is classified as a corneal stromal dystrophy but also involves the Descemet membrane and the corneal endothelium.Differential diagnosisThe clinical features of MCD are similar to the corneal involvement found in the systemic mucopolysaccharidoses, such as mucopolysaccharidosis type IH and IS and the mucolipidoses (see these terms).Genetic counselingAn autosomal recessive mode of inheritance has been shown in most cases, but some cases are of unknown etiology.Management and treatmentSince the condition affects the entire corneal stroma, Descemet membrane and corneal endothelium, lamellar keratoplasty does not excise all damaged tissue. Corneal transplantation may therefore be needed. Vision can be restored by corneal grafting but opacities may recur in the graft after many years.Visit the Orphanet disease page for more resources.

MalaCards based summary : Macular Dystrophy, Corneal, also known as macular corneal dystrophy, is related to corneal dystrophy, meesmann and corneal dystrophy. An important gene associated with Macular Dystrophy, Corneal is CHST6 (Carbohydrate Sulfotransferase 6), and among its related pathways/superpathways is Glycosaminoglycan biosynthesis - keratan sulfate. The drugs Fomepizole and Antidotes have been mentioned in the context of this disorder. Affiliated tissues include endothelial, eye and skin, and related phenotypes are photophobia and abnormality of metabolism/homeostasis

Disease Ontology : ¹² A corneal dystrophy that is characterized by corneal haze, bilateral loss of vision, eventually necessitating corneal transplantation resulting from progressive punctate opacities in the cornea.

OMIM : ⁵⁷ Macular corneal dystrophy (MCD) is an autosomal recessive disorder in which progressive punctate opacities in the cornea result in bilateral loss of vision, eventually necessitating corneal transplantation. MCD is classified into 2 subtypes, type I and type II, defined by the respective absence and presence of sulfated keratan sulfate in the patient serum, although both types have clinically indistinguishable phenotypes (summary by Akama et al., 2000). (217800)

UniProtKB/Swiss-Prot : ⁷⁵ Macular dystrophy, corneal: An ocular disease characterized by bilateral, progressive corneal opacification, and reduced corneal sensitivity. Onset occurs in the first decade, usually between ages 5 and 9. Painful attacks with photophobia, foreign body sensations, and recurrent erosions occur in most patients. The disease is due to deposition of an unsulfated keratan sulfate both within the intracellular space (within the keratocytes and endothelial cells) and in the extracellular corneal stroma. Macular corneal dystrophy is divided into the clinically indistinguishable types I, IA, and II based on analysis of the normally sulfated, or antigenic, keratan sulfate levels in serum and immunohistochemical evaluation of the cornea. Patients with types I and IA macular corneal dystrophy have undetectable serum levels of antigenic keratan sulfate, whereas those with type II macular corneal dystrophy have normal or low levels, depending on the population examined.

Wikipedia : ⁷⁶ Macular corneal dystrophy, also known as Fehr corneal dystrophy named for German ophthalmologist Oskar... more...

Clinical features from OMIM:

217800

#	Description	GenomeRNAi Source Accession	Score	Top Affiliating Genes
1	Increased shRNA abundance (Z-score > 2)	GR00366-A-100	9.4	KRT12
2	Increased shRNA abundance (Z-score > 2)	GR00366-A-12	9.4	KRT12
3	Increased shRNA abundance (Z-score > 2)	GR00366-A-137	9.4	SULT1C2
4	Increased shRNA abundance (Z-score > 2)	GR00366-A-147	9.4	KRT12 SULT1C2
5	Increased shRNA abundance (Z-score > 2)	GR00366-A-177	9.4	KRT12
6	Increased shRNA abundance (Z-score > 2)	GR00366-A-195	9.4	SULT1C2
7	Increased shRNA abundance (Z-score > 2)	GR00366-A-215	9.4	KRT12
8	Increased shRNA abundance (Z-score > 2)	GR00366-A-43	9.4	SULT1C2
9	Increased shRNA abundance (Z-score > 2)	GR00366-A-78	9.4	SULT1C2
10	Increased shRNA abundance (Z-score > 2)	GR00366-A-93	9.4	KRT12
11	Increased shRNA abundance (Z-score > 2)	GR00366-A-99	9.4	SULT1C2

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