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Leber congenital amaurosis 6(LCA6)

MedGen UID:
344245
Concept ID:
C1854260
Congenital Abnormality; Disease or Syndrome
Synonyms: LCA6; RPGRIP1-Related Leber Congenital Amaurosis
 
Gene (location): RPGRIP1 (14q11.2)
 
Monarch Initiative: MONDO:0013446
OMIM®: 613826

Definition

Leber congenital amaurosis comprises a group of early-onset childhood retinal dystrophies characterized by vision loss, nystagmus, and severe retinal dysfunction. Patients usually present at birth with profound vision loss and pendular nystagmus. Electroretinogram (ERG) responses are usually nonrecordable. Other clinical findings may include high hypermetropia, photodysphoria, oculodigital sign, keratoconus, cataracts, and a variable appearance to the fundus (summary by Chung and Traboulsi, 2009). For a general description and a discussion of genetic heterogeneity of LCA, see 204000. [from OMIM]

Additional description

From MedlinePlus Genetics
In very rare cases, delayed development and intellectual disability have been reported in people with the features of Leber congenital amaurosis. Because of the visual loss, affected children may become isolated. Providing children with opportunities to play, hear, touch, understand and other early educational interventions may prevent developmental delays in children with Leber congenital amaurosis.

At least 20 genetic types of Leber congenital amaurosis have been described. The types are distinguished by their genetic cause, patterns of vision loss, and related eye abnormalities.

A specific behavior called Franceschetti's oculo-digital sign is characteristic of Leber congenital amaurosis. This sign consists of affected individuals poking, pressing, and rubbing their eyes with a knuckle or finger. Poking their eyes often results in the sensation of flashes of light called phosphenes. Researchers suspect that this behavior may contribute to deep-set eyes in affected children.

Leber congenital amaurosis is also associated with other vision problems, including an increased sensitivity to light (photophobia), involuntary movements of the eyes (nystagmus), and extreme farsightedness (hyperopia). The pupils, which usually expand and contract in response to the amount of light entering the eye, do not react normally to light. Instead, they expand and contract more slowly than normal, or they may not respond to light at all.

Leber congenital amaurosis, also known as LCA, is an eye disorder that is present from birth (congenital). This condition primarily affects the retina, which is the specialized tissue at the back of the eye that detects light and color. People with this disorder typically have severe visual impairment beginning at birth or shortly afterward. The visual impairment tends to be severe and may worsen over time.  https://medlineplus.gov/genetics/condition/leber-congenital-amaurosis

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.
Keratoconus
MedGen UID:
44015
Concept ID:
C0022578
Disease or Syndrome
A cone-shaped deformity of the cornea characterized by the presence of corneal distortion secondary to thinning of the apex.
Cataract
MedGen UID:
39462
Concept ID:
C0086543
Disease or Syndrome
A cataract is an opacity or clouding that develops in the crystalline lens of the eye or in its capsule.
Pendular nystagmus
MedGen UID:
78770
Concept ID:
C0271388
Disease or Syndrome
Rhythmic, involuntary sinusoidal oscillations of one or both eyes. The waveform of pendular nystagmus may occur in any direction.
Severely reduced visual acuity
MedGen UID:
226987
Concept ID:
C1301509
Disease or Syndrome
Severe reduction of the ability to see defined as visual acuity less than 6/60 (20/200 in US notation; 0.1 in decimal notation) but at least 3/60 (20/400 in US notation; 0.05 in decimal notation).
Undetectable electroretinogram
MedGen UID:
383742
Concept ID:
C1855685
Finding
Lack of any response to stimulation upon electroretinography.
Hyperopia, high
MedGen UID:
341009
Concept ID:
C1855925
Finding
A severe form of hypermetropia with over +5.00 diopters.
Attenuation of retinal blood vessels
MedGen UID:
480605
Concept ID:
C3278975
Finding

Recent clinical studies

Diagnosis

Sato S, Morimoto T, Tanaka S, Hotta K, Fujikado T, Tsujikawa M, Nishida K
BMC Ophthalmol 2020 Jul 31;20(1):313. doi: 10.1186/s12886-020-01577-9. PMID: 32736544Free PMC Article
Fakhratova M
Ophthalmic Genet 2013 Dec;34(4):234-7. Epub 2013 Jan 2 doi: 10.3109/13816810.2012.755552. PMID: 23278760

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