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X-linked cone-rod dystrophy 1(CORDX1)

MedGen UID:
336777
Concept ID:
C1844776
Disease or Syndrome
Synonym: CORDX1
 
Gene (location): RPGR (Xp11.4)
 
Monarch Initiative: MONDO:0010566
OMIM®: 304020

Definition

X-linked cone-rod dystrophy is a rare, progressive visual disorder primarily affecting cone photoreceptors (Demirci et al., 2002). Affected individuals, essentially all of whom are males, present with decreased visual acuity, myopia, photophobia, abnormal color vision, full peripheral visual fields, decreased photopic electroretinographic responses, and granularity of the macular retinal pigment epithelium. The degree of rod photoreceptor involvement is variable, with increasing degeneration. Although penetrance appears to be nearly 100%, there is variable expressivity with respect to age at onset, severity of symptoms, and findings (Hong et al., 1994). Genetic Heterogeneity of X-linked Cone-Rod Dystrophy Additional forms of X-linked cone-rod dystrophy include CORDX2 (300085), mapped to chromosome Xq27, and CORDX3 (300476), caused by mutation in the CACNA1F gene (300110) on chromosome Xp11.23. For a discussion of autosomal forms of cone-rod dystrophy, see CORD2 (120970). [from OMIM]

Additional description

From MedlinePlus Genetics
Cone-rod dystrophy is a group of related eye disorders that causes vision loss, which becomes more severe over time. These disorders affect the retina, which is the layer of light-sensitive tissue at the back of the eye. In people with cone-rod dystrophy, vision loss occurs as the light-sensing cells of the retina gradually deteriorate.

There are more than 30 types of cone-rod dystrophy, which are distinguished by their genetic cause and their pattern of inheritance: autosomal recessive, autosomal dominant, and X-linked. Additionally, cone-rod dystrophy can occur alone without any other signs and symptoms or it can occur as part of a syndrome that affects multiple parts of the body.

The first signs and symptoms of cone-rod dystrophy, which often occur in childhood, are usually decreased sharpness of vision (visual acuity) and increased sensitivity to light (photophobia). These features are typically followed by impaired color vision (dyschromatopsia), blind spots (scotomas) in the center of the visual field, and partial side (peripheral) vision loss. Over time, affected individuals develop night blindness and a worsening of their peripheral vision, which can limit independent mobility. Decreasing visual acuity makes reading increasingly difficult and most affected individuals are legally blind by mid-adulthood. As the condition progresses, individuals may develop involuntary eye movements (nystagmus).  https://medlineplus.gov/genetics/condition/cone-rod-dystrophy

Clinical features

From HPO
Photophobia
MedGen UID:
43220
Concept ID:
C0085636
Sign or Symptom
Excessive sensitivity to light with the sensation of discomfort or pain in the eyes due to exposure to bright light.
Myopia
MedGen UID:
44558
Concept ID:
C0027092
Disease or Syndrome
Nearsightedness, also known as myopia, is an eye condition that causes blurry distance vision. People who are nearsighted have more trouble seeing things that are far away (such as when driving) than things that are close up (such as when reading or using a computer). If it is not treated with corrective lenses or surgery, nearsightedness can lead to squinting, eyestrain, headaches, and significant visual impairment.\n\nNearsightedness usually begins in childhood or adolescence. It tends to worsen with age until adulthood, when it may stop getting worse (stabilize). In some people, nearsightedness improves in later adulthood.\n\nFor normal vision, light passes through the clear cornea at the front of the eye and is focused by the lens onto the surface of the retina, which is the lining of the back of the eye that contains light-sensing cells. People who are nearsighted typically have eyeballs that are too long from front to back. As a result, light entering the eye is focused too far forward, in front of the retina instead of on its surface. It is this change that causes distant objects to appear blurry. The longer the eyeball is, the farther forward light rays will be focused and the more severely nearsighted a person will be.\n\nNearsightedness is measured by how powerful a lens must be to correct it. The standard unit of lens power is called a diopter. Negative (minus) powered lenses are used to correct nearsightedness. The more severe a person's nearsightedness, the larger the number of diopters required for correction. In an individual with nearsightedness, one eye may be more nearsighted than the other.\n\nEye doctors often refer to nearsightedness less than -5 or -6 diopters as "common myopia." Nearsightedness of -6 diopters or more is commonly called "high myopia." This distinction is important because high myopia increases a person's risk of developing other eye problems that can lead to permanent vision loss or blindness. These problems include tearing and detachment of the retina, clouding of the lens (cataract), and an eye disease called glaucoma that is usually related to increased pressure within the eye. The risk of these other eye problems increases with the severity of the nearsightedness. The term "pathological myopia" is used to describe cases in which high myopia leads to tissue damage within the eye.
Night blindness
MedGen UID:
10349
Concept ID:
C0028077
Disease or Syndrome
Inability to see well at night or in poor light.
Nystagmus
MedGen UID:
45166
Concept ID:
C0028738
Disease or Syndrome
Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms.
Color vision defect
MedGen UID:
115964
Concept ID:
C0234629
Finding
An anomaly in the ability to discriminate between or recognize colors.
Reduced visual acuity
MedGen UID:
65889
Concept ID:
C0234632
Finding
Diminished clarity of vision.
Retinal pigment epithelial atrophy
MedGen UID:
333564
Concept ID:
C1840457
Finding
Atrophy (loss or wasting) of the retinal pigment epithelium observed on fundoscopy or fundus imaging.
Retinal pigment epithelial mottling
MedGen UID:
347513
Concept ID:
C1857644
Finding
Mottling (spots or blotches with different shades) of the retinal pigment epithelium, i.e., localized or generalized fundal pigment granularity associated with processes at the level of the retinal pigment epithelium.
Visual impairment
MedGen UID:
777085
Concept ID:
C3665347
Finding
Visual impairment (or vision impairment) is vision loss (of a person) to such a degree as to qualify as an additional support need through a significant limitation of visual capability resulting from either disease, trauma, or congenital or degenerative conditions that cannot be corrected by conventional means, such as refractive correction, medication, or surgery.
Hypoautofluorescent macular lesion
MedGen UID:
893087
Concept ID:
C4073102
Finding
Decreased amount of autofluorescence in the macula as ascertained by fundus autofluorescence imaging.

Professional guidelines

PubMed

Stingl K, Kempf M, Bartz-Schmidt KU, Dimopoulos S, Reichel F, Jung R, Kelbsch C, Kohl S, Kortüm FC, Nasser F, Peters T, Wilhelm B, Wissinger B, Wozar F, Zrenner E, Fischer MD, Stingl K
Br J Ophthalmol 2022 Jun;106(6):831-838. Epub 2021 Jan 20 doi: 10.1136/bjophthalmol-2020-318286. PMID: 33472769Free PMC Article
Yang L, Yin X, Feng L, You D, Wu L, Chen N, Li A, Li G, Ma Z
PLoS One 2014;9(1):e85752. Epub 2014 Jan 15 doi: 10.1371/journal.pone.0085752. PMID: 24454928Free PMC Article

Recent clinical studies

Etiology

Daich Varela M, Conti GM, Malka S, Vaclavik V, Mahroo OA, Webster AR, Tran V, Michaelides M
Ophthalmology 2023 Dec;130(12):1327-1335. Epub 2023 Aug 5 doi: 10.1016/j.ophtha.2023.07.027. PMID: 37544434Free PMC Article
Georgiou M, Robson AG, Jovanovic K, Guimarães TAC, Ali N, Pontikos N, Uwaydat SH, Mahroo OA, Cheetham ME, Webster AR, Hardcastle AJ, Michaelides M
Ophthalmology 2023 Apr;130(4):413-422. Epub 2022 Nov 22 doi: 10.1016/j.ophtha.2022.11.015. PMID: 36423731Free PMC Article
Tsang SH, Sharma T
Adv Exp Med Biol 2018;1085:53-60. doi: 10.1007/978-3-319-95046-4_12. PMID: 30578485
Sahel JA, Marazova K, Audo I
Cold Spring Harb Perspect Med 2014 Oct 16;5(2):a017111. doi: 10.1101/cshperspect.a017111. PMID: 25324231Free PMC Article
Hamel CP
Orphanet J Rare Dis 2007 Feb 1;2:7. doi: 10.1186/1750-1172-2-7. PMID: 17270046Free PMC Article

Diagnosis

Daich Varela M, Conti GM, Malka S, Vaclavik V, Mahroo OA, Webster AR, Tran V, Michaelides M
Ophthalmology 2023 Dec;130(12):1327-1335. Epub 2023 Aug 5 doi: 10.1016/j.ophtha.2023.07.027. PMID: 37544434Free PMC Article
Georgiou M, Robson AG, Jovanovic K, Guimarães TAC, Ali N, Pontikos N, Uwaydat SH, Mahroo OA, Cheetham ME, Webster AR, Hardcastle AJ, Michaelides M
Ophthalmology 2023 Apr;130(4):413-422. Epub 2022 Nov 22 doi: 10.1016/j.ophtha.2022.11.015. PMID: 36423731Free PMC Article
Falsini B, Placidi G, De Siena E, Chiurazzi P, Minnella AM, Savastano MC, Ziccardi L, Parisi V, Iarossi G, Percio M, Piteková B, Marceddu G, Maltese PE, Bertelli M
Sci Rep 2022 Mar 8;12(1):3774. doi: 10.1038/s41598-022-07618-1. PMID: 35260635Free PMC Article
Hamel CP
Orphanet J Rare Dis 2007 Feb 1;2:7. doi: 10.1186/1750-1172-2-7. PMID: 17270046Free PMC Article
Hamel C
Orphanet J Rare Dis 2006 Oct 11;1:40. doi: 10.1186/1750-1172-1-40. PMID: 17032466Free PMC Article

Therapy

Wood LJ, Jolly JK, Andrews CD, Wilson IR, Hickey D, Cehajic-Kapetanovic J, Maclaren RE
Clin Exp Optom 2021 Jan;104(1):90-94. doi: 10.1111/cxo.13087. PMID: 32372497
Sahel JA, Marazova K, Audo I
Cold Spring Harb Perspect Med 2014 Oct 16;5(2):a017111. doi: 10.1101/cshperspect.a017111. PMID: 25324231Free PMC Article

Prognosis

Daich Varela M, Conti GM, Malka S, Vaclavik V, Mahroo OA, Webster AR, Tran V, Michaelides M
Ophthalmology 2023 Dec;130(12):1327-1335. Epub 2023 Aug 5 doi: 10.1016/j.ophtha.2023.07.027. PMID: 37544434Free PMC Article
Georgiou M, Robson AG, Jovanovic K, Guimarães TAC, Ali N, Pontikos N, Uwaydat SH, Mahroo OA, Cheetham ME, Webster AR, Hardcastle AJ, Michaelides M
Ophthalmology 2023 Apr;130(4):413-422. Epub 2022 Nov 22 doi: 10.1016/j.ophtha.2022.11.015. PMID: 36423731Free PMC Article
Alsalamah AK, Khan AO
Middle East Afr J Ophthalmol 2020 Apr-Jun;27(2):86-90. Epub 2020 Jul 20 doi: 10.4103/meajo.MEAJO_106_20. PMID: 32874040Free PMC Article
Hamel CP
Orphanet J Rare Dis 2007 Feb 1;2:7. doi: 10.1186/1750-1172-2-7. PMID: 17270046Free PMC Article
Hamel C
Orphanet J Rare Dis 2006 Oct 11;1:40. doi: 10.1186/1750-1172-1-40. PMID: 17032466Free PMC Article

Clinical prediction guides

Daich Varela M, Conti GM, Malka S, Vaclavik V, Mahroo OA, Webster AR, Tran V, Michaelides M
Ophthalmology 2023 Dec;130(12):1327-1335. Epub 2023 Aug 5 doi: 10.1016/j.ophtha.2023.07.027. PMID: 37544434Free PMC Article
Georgiou M, Robson AG, Jovanovic K, Guimarães TAC, Ali N, Pontikos N, Uwaydat SH, Mahroo OA, Cheetham ME, Webster AR, Hardcastle AJ, Michaelides M
Ophthalmology 2023 Apr;130(4):413-422. Epub 2022 Nov 22 doi: 10.1016/j.ophtha.2022.11.015. PMID: 36423731Free PMC Article
Williams KM, Georgiou M, Kalitzeos A, Chow I, Hysi PG, Robson AG, Lingham G, Chen FK, Mackey DA, Webster AR, Hammond CJ, Prokhoda P, Carroll J, Michaelides M, Mahroo OA
Invest Ophthalmol Vis Sci 2022 Jun 1;63(6):15. doi: 10.1167/iovs.63.6.15. PMID: 35704304Free PMC Article
Gardner JC, Webb TR, Kanuga N, Robson AG, Holder GE, Stockman A, Ripamonti C, Ebenezer ND, Ogun O, Devery S, Wright GA, Maher ER, Cheetham ME, Moore AT, Michaelides M, Hardcastle AJ
Am J Hum Genet 2010 Jul 9;87(1):26-39. Epub 2010 Jun 24 doi: 10.1016/j.ajhg.2010.05.019. PMID: 20579627Free PMC Article
Vervoort R, Wright AF
Hum Mutat 2002 May;19(5):486-500. doi: 10.1002/humu.10057. PMID: 11968081

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