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| Microphthalmia |
| Classification and external resources |
Unilateral Microphthalmia |
| ICD-10 |
Q11.2 |
| ICD-9 |
743.1 |
| DiseasesDB |
29618 |
| eMedicine |
oph/572 |
| GeneReviews |
- Anophthalmia / Microphthalmia Overview
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Microphthalmia also referred to as microphthalmos, nanophthalmia or nanophthalmos, is a developmental disorder of the eye that literally means small eye (micros = small; ophthalmos = eye). One (Unilateral Microphthalmia) or both (Bilateral Microphthalmia) eyes may be involved [1]
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Contents
- 1 Presentation
- 2 Causes
- 3 See also
- 4 References
- 5 External links
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Presentation
The presence of a small eye within the orbit can be a normal incidental finding but in most cases it is abnormal and results in blindness. The incidence is 14 per 100,000 and the condition affects 3-11% of blind children.
Causes
Microphthalmia in newborns is sometimes associated with fetal alcohol syndrome[1] or infections during pregnancy, particularly herpes simplex virus, rubella and cytomegalovirus (CMV), but the evidence is inconclusive. Genetic causes of microphthalmia include chromosomal abnormalities (trisomy 13 (Patau syndrome), Triploid Syndrome, and Wolf-Hirschhorn Syndrome) or monogenetic Mendelian disorders. The latter maybe autosomal dominant, autosomal recessive or X linked. Genes that have been implicated in microphthamia include many transcription and regulatory factors. Those identified from family studies include the following:
| HGNC symbol |
Description |
OMIM |
Type |
| BCOR |
BCL6 corepressor |
300166 |
MCOPS2 |
| CRYBA4 |
crystallin, beta A4 |
| FOXE3 |
forkhead box E3 |
| GDF6 |
growth differentiation factor 6 |
| MITF |
microphthalmia-associated transcription factor |
| OTX2 |
orthodenticle homeobox 2 |
| PAX6 |
paired box 6 |
| PITX3 |
Paired-like homeodomain transcription factor 3 |
| RAX |
retina and anterior neural fold homeobox |
| SHH |
sonic hedgehog homolog |
| SIX6 |
SIX homeobox 6 |
| SOX2 |
SRY (sex determining region Y)-box 2 |
206900 |
MCOPS3 |
| VSX1 |
visual system homeobox 1 VSX1 |
visual system homeobox 1 |
| RAB18 |
Ras-related protein 18 |
| VSX2 (CHX10) |
visual system homeobox 2 |
How these genes result in the eye disorder is unknown but it has been postulated that interference with the process of eye growth after birth may be involved in contrast to anophthalmia (absence of eye ball) which originates much earlier during foetal development. SOX2 has been implicated in a substantial number (10-15%) of cases and in many other cases failure to develop the ocular lens often results in microphthamia. Microphthalmia-associated transcription factor (MITF) located on chromosome 14q32 is associated with one form of isolated microphthalmia (MCOP1. In mammals the failure of expression of the transcription factor, MITF (microphthalmia-associated transcription factor), in the pigmented retina prevents this structure from fully differentiating. This in turn causes a malformation of the choroid fissure of the eye, resulting in the drainage of vitreous humor fluid. Without this fluid, the eye fails to enlarge, thus the name microphthalmia.The gene encoding the microphthalmia-associated transcription factor (MITF) is a member of the basic helix-loop-helix-leucine zipper (bHLH-ZIP) family. Waardenburg syndrome type 2 (WS type 2) in humans is also a type of microphthalmia syndrome. Mutations in MITF gene are thought to be responsible for this syndrome. The human MITF gene is homologous to the mouse MITF gene (aka mouse mi or microphthalmia gene); mouse with mutations in this gene are hypopigmented in their fur. The identification of the genetics of WS type 2 owes a lot to observations of phenotypes of MITF mutant mice.
See also
- Abdominal Musculature Absent With Microphthalmia And Joint Laxity
References
- ^ a b "Definition of Micropthalmia". MedicineNet. http://www.medterms.com/script/main/art.asp?articlekey=16198. Retrieved 2009-01-01.
External links
- GeneReviews/NCBI/NIH/UW entry on Anophthalmia / Microphthalmia Overview
- Parent Support group for parents with Anophthalmic and Microphthalmic children MAPS
- Anophthalmia and Microphthalmia Resource Guide from the National Eye Institute (NEI).
- GeneReviews/NCBI/NIH/UW entry on Microphthalmia with Linear Skin Defects Syndrome
- MACS The Micro and Anophthalmic Childrens Society - Offers support and Information to families in the UK and around the world
- Ensembl
- HUGO Gene Nomenclature Committee
- OMIM-Online Mendelian Inheritance in Man
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Congenital malformations and deformations of eyes (Q10–Q15, 743)
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| Adnexa |
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Eyelid
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- Ptosis
- Ectropion
- Entropion
- Distichia
- Blepharophimosis
- Ablepharon
- Marcus Gunn phenomenon
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Lacrimal apparatus
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- Congenital lacrimal duct obstruction
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| Globe |
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Entire eye
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- Anophthalmia (Cystic eyeball, Cryptophthalmos)
- Microphthalmia
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Lens
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Iris
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Anterior segment
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Cornea
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- Keratoglobus
- Megalocornea
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Other
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- Buphthalmos
- Coloboma (Coloboma of optic nerve)
- Hydrophthalmos
- Norrie disease
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anat (g/a/p)/phys/devp/prot
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proc, drug (S1A/1E/1F/1L)
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UpToDate Contents
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English Journal
- Pro-Survival Role of MITF in Melanoma.
- Hartman ML1, Czyz M1.
- The Journal of investigative dermatology.J Invest Dermatol.2015 Feb;135(2):352-358. doi: 10.1038/jid.2014.319. Epub 2014 Aug 21.
- Melanoma is a therapy-resistant skin cancer due to numerous mechanisms supporting cell survival. Although components of melanoma cytoprotective mechanisms are overexpressed in many types of tumors, some of their regulators are characteristic for melanoma. Several genes mediating pro-survival functio
- PMID 25142731
- Melanogenesis and antioxidant defense system in normal human melanocytes cultured in the presence of chlorpromazine.
- Otreba M1, Wrześniok D, Beberok A, Rok J, Buszman E.
- Toxicology in vitro : an international journal published in association with BIBRA.Toxicol In Vitro.2015 Feb;29(1):221-7.
- Chlorpromazine is used in the treatment of schizophrenia and psychotic disorders and belongs to phenothiazine class of neuroleptic drugs. It shows severe side effects such as extrapyramidal symptoms as well as ocular and skin disorders, but the mechanism is still not fully established. The aim of th
- PMID 25449126
- Epigenetic regulation in human melanoma: Past and future.
- Sarkar D1, Leung EY, Baguley BC, Finlay GJ, Askarian-Amiri ME.
- Epigenetics : official journal of the DNA Methylation Society.Epigenetics.2015 Jan 14:0. [Epub ahead of print]
- Abstract The development and progression of melanoma have been attributed to independent or combined genetic and epigenetic events. There has been remarkable progress in understanding melanoma pathogenesis in terms of genetic alterations. However, recent studies have revealed a complex involvement o
- PMID 25587943
Japanese Journal
- The newt (Cynops pyrrhogaster ) RPE65 promoter: molecular cloning, characterization and functional analysis
- Identification of Polymorphisms in Plumage Color Related Genes in Korean Native Ducks
- Journal of the Faculty of Agriculture, Kyushu University 60(1), 119-126, 2015-02-27
- NAID 120005661337
- α-MSH stimulation contributes to TGF-β1 production via MC1R-MITF signaling pathway in melanoma cell
Related Links
- Microphthalmia is an eye abnormality that arises before birth. In this condition, one or both eyeballs are abnormally small. In some affected individuals, the eyeball may appear to be completely missing; however, even in ...
- microphthalmos [mi″krof-thal´mus] a developmental defect causing moderate or severe reduction in size of the eye. mi·croph·thal·mos (mī'krof-thal'mos), Abnormal smallness of the eye. Synonym(s): microphthalmia, nanophthalmia, nanophthalmos
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小眼球症関連転写因子
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