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Cone-rod dystrophy 2(CORD2)

MedGen UID:
483485
Concept ID:
C3489532
Disease or Syndrome
Synonyms: CONE-ROD RETINAL DYSTROPHY; Cone-rod retinal dystrophy 2; CORD2
 
Gene (location): CRX (19q13.33)
 
Monarch Initiative: MONDO:0007362
OMIM®: 120970

Definition

Cone-rod dystrophy (CORD) characteristically leads to early impairment of vision. An initial loss of color vision and of visual acuity is followed by nyctalopia (night blindness) and loss of peripheral visual fields. In extreme cases, these progressive symptoms are accompanied by widespread, advancing retinal pigmentation and chorioretinal atrophy of the central and peripheral retina (Moore, 1992). In many families, perhaps a majority, central and peripheral chorioretinal atrophy is not found (Tzekov, 1998). Genetic Heterogeneity of Autosomal Cone-Rod Dystrophy There are several other autosomal forms of CORD for which the molecular basis is known. CORD3 (604116) is caused by mutation in the ABCA4 gene (601691) on chromosome 1p22. CORD5 (600977) is caused by mutation in the PITPNM3 gene (608921) on chromosome 17p13. CORD6 (601777) is caused by mutation in the GUCY2D gene (600179) on chromosome 17p13.1. CORD9 (612775) is caused by mutation in the ADAM9 gene (602713) on chromosome 8p11. CORD10 (610283) is caused by mutation in the SEMA4A gene (607292) on chromosome 1q22. CORD11 (610381) is caused by mutation in the RAXL1 gene (610362) on chromosome 19p13. CORD12 (612657) is caused by mutation in the PROM1 gene (604365) on chromosome 4p15. CORD13 (608194) is caused by mutation in the RPGRIP1 gene (605446) on chromosome 14q11. CORD14 (see 602093) is caused by mutation in the GUCA1A gene (600364) on chromosome 6p21. CORD15 (613660) is caused by mutation in the CDHR1 gene (609502) on chromosome 10q23. CORD16 (614500) is caused by mutation in the C8ORF37 gene (614477) on chromosome 8q22. CORD18 (615374) is caused by mutation in the RAB28 gene (612994) on chromosome 4p15. CORD19 (615860) is caused by mutation in the TTLL5 gene (612268) on chromosome 14q24. CORD20 (615973) is caused by mutation in the POC1B gene (614784) on chromosome 12q21. CORD21 (616502) is caused by mutation in the DRAM2 gene (613360) on chromosome 1p13. CORD22 (619531) is caused by mutation in the TLCD3B gene (615175) on chromosome 16p11. CORD23 (see 613428) is caused by mutation in the C2ORF71 gene (PCARE; 613425) on chromosome 2p23. CORD24 (620342) is caused by mutation in the UNC119 gene (604011) on chromosome 17q11. A diagnosis of CORD was made in an individual with a mutation in the AIPL1 gene (604392.0004) on chromosome 17p13.1, as well as in an individual with a mutation in the UNC119 gene (604011.0001) on chromosome 17q11.2. Other mapped loci for autosomal CORD include CORD1 (600624) on chromosome 18q21.1-q21.3; CORD7 (603649) on chromosome 6q14; CORD8 (605549) on chromosome 1q12-q24; and CORD17 (615163) on chromosome 10q26. For a discussion of X-linked forms of cone-rod dystrophy, see CORDX1 (304020). [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.

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).

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.  https://medlineplus.gov/genetics/condition/cone-rod-dystrophy

Clinical features

From HPO
Night blindness
MedGen UID:
10349
Concept ID:
C0028077
Disease or Syndrome
Inability to see well at night or in poor light.
Central scotoma
MedGen UID:
57750
Concept ID:
C0152191
Finding
An area of depressed vision located at the point of fixation and that interferes with central vision.
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.
Constriction of peripheral visual field
MedGen UID:
68613
Concept ID:
C0235095
Finding
An absolute or relative decrease in retinal sensitivity extending from edge (periphery) of the visual field in a concentric pattern. The visual field is the area that is perceived simultaneously by a fixating eye.
Peripheral visual field loss
MedGen UID:
116124
Concept ID:
C0241688
Finding
Loss of peripheral vision with retention of central vision, resulting in a constricted circular tunnel-like field of vision.
Metamorphopsia
MedGen UID:
75739
Concept ID:
C0271185
Sign or Symptom
A visual anomaly in which images appear distorted. A grid of straight lines appears wavy and parts of the grid may appear blank.
Blindness
MedGen UID:
99138
Concept ID:
C0456909
Disease or Syndrome
Blindness is the condition of lacking visual perception defined as a profound reduction in visual perception. On the 6m visual acuity scale, blindness is defined as less than 3/60. On the 20ft visual acuity scale, blindness is defined as less than 20/400. On the decimal visual acuity scale, blindness is defined as less than 0.05. Blindness is typically characterized by a visual field of no greater than 10 degrees in radius around central fixation.
Abnormal electroretinogram
MedGen UID:
96908
Concept ID:
C0476397
Finding
Any abnormality of the electrical responses of various cell types in the retina as measured by electroretinography.
Macular hyperpigmentation
MedGen UID:
488933
Concept ID:
C0745109
Finding
Increased amount of pigmentation in the macula lutea.
Bone spicule pigmentation of the retina
MedGen UID:
323029
Concept ID:
C1836926
Finding
Pigment migration into the retina in a bone-spicule configuration (resembling the nucleated cells within the lacuna of bone).
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.
Chorioretinal atrophy
MedGen UID:
884881
Concept ID:
C4048273
Disease or Syndrome
Atrophy of the choroid and retinal layers of the fundus.
Cone-rod dystrophy
MedGen UID:
896366
Concept ID:
C4085590
Disease or Syndrome
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.\n\nThe 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).\n\nCone-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.

Term Hierarchy

Professional guidelines

PubMed

Wang WC, Huang CH, Chung HH, Chen PL, Hu FR, Yang CH, Yang CM, Lin CW, Hsu CC, Chen TC
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Genes (Basel) 2020 Nov 27;11(12) doi: 10.3390/genes11121421. PMID: 33261146Free PMC Article

Recent clinical studies

Diagnosis

Nguyen XT, Talib M, van Schooneveld MJ, Wijnholds J, van Genderen MM, Schalij-Delfos NE, Klaver CCW, Talsma HE, Fiocco M, Florijn RJ, Ten Brink JB, Cremers FPM, Meester-Smoor MA, van den Born LI, Hoyng CB, Thiadens AAHJ, Bergen AA, Boon CJF
Am J Ophthalmol 2022 Feb;234:37-48. Epub 2021 Jul 25 doi: 10.1016/j.ajo.2021.07.021. PMID: 34320374
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Acta Ophthalmol 2012 May;90(3):277-86. Epub 2011 Aug 4 doi: 10.1111/j.1755-3768.2011.02205.x. PMID: 21812942

Prognosis

Nguyen XT, Talib M, van Schooneveld MJ, Wijnholds J, van Genderen MM, Schalij-Delfos NE, Klaver CCW, Talsma HE, Fiocco M, Florijn RJ, Ten Brink JB, Cremers FPM, Meester-Smoor MA, van den Born LI, Hoyng CB, Thiadens AAHJ, Bergen AA, Boon CJF
Am J Ophthalmol 2022 Feb;234:37-48. Epub 2021 Jul 25 doi: 10.1016/j.ajo.2021.07.021. PMID: 34320374
Ma DJ, Lee HS, Kim K, Choi S, Jang I, Cho SH, Yoon CK, Lee EK, Yu HG
BMC Med Genomics 2021 Mar 10;14(1):74. doi: 10.1186/s12920-021-00874-6. PMID: 33691693Free PMC Article

Clinical prediction guides

Ma DJ, Lee HS, Kim K, Choi S, Jang I, Cho SH, Yoon CK, Lee EK, Yu HG
BMC Med Genomics 2021 Mar 10;14(1):74. doi: 10.1186/s12920-021-00874-6. PMID: 33691693Free PMC Article

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