Birdshot chorioretinopathy

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Birdshot chorioretinopathy (HLA-A29 uveitis)
Other namesMultiple small, cream-colored lesions, symmetrically scattered mainly around the optic disk, Vitiliginous choroiditis
Characteristic hypo-pigmentation in birdshot chorioretinopathy
SpecialtyOphthalmology Edit this on Wikidata

Birdshot chorioretinopathy, now commonly named birdshot uveitis or HLA-A29 uveitis,

eyes. It causes severe, progressive inflammation of both the choroid and retina.[2][3][4]

Affected individuals are almost exclusively Caucasian and usually diagnosed in the fourth to sixth decade of their lives.[5]

Symptoms and signs

Symptoms of this disorder include

birdshot from a shotgun, but these spots might not be present in early stages.[citation needed
]

Pathophysiology

Birdshot chorioretinopathy is a rare form of posterior

T-lymphocytes in the pathogenesis. Birdshot chorioretinopathy is associated with IL-17, a hallmark cytokine of TH17 cells that play an important role in autoimmunity.[6][7] The disease affects typically middle-aged or elderly caucasians. HLA-A29 is less prevalent in Asia and no birdshot chorioretinopathy cases have been reported in Asia. When birdshot chorioretinopathy is suspected, a person is usually tested to determine if they are HLA-A29 positive. Although previously HLA-A29 testing was not considered necessary for definitive diagnosis, because HLA-A29 is also common in the general healthy population (7%). An increasing number of specialists consider the presence of HLA-A29 critical for diagnosis.[1]
Additional (genetic or environmental) or unknown factors may be associated with HLA-A29 in the pathogenesis.

In 2014, Kuiper et al. conducted a genome-wide association study in birdshot chorioretinopathy and studied the entire genome of Dutch, Spanish and English patients. This large genetic study ascertained HLA-A29:02 as the primary risk factor and identified the endoplasmic reticulum aminopeptidase (ERAP) 2 gene strongly associated with birdshot chorioretinopathy.[8] Genetic variants near ERAP2 on chromosome 5 resulted in high mRNA and protein expression of this aminopeptidase in BSCR patients. ERAP2 is an aminopeptidase that, together with the closely related ERAP1, trims peptides in the endoplasmic reticulum and loads these peptides on HLA molecules for presentation to T cells of the immune system. ERAP-HLA associations have also been reported in Ankylosing spondylitis and Behcet's disease, suggesting shared pathogenic pathways among these diseases. The combined Birdshot risk polymorphisms at 5q15 linked to ERAP1 and ERAP2 genes (T-rs10044354-C-rs2287987) are only observed in HLA-A29-positive individuals in populations in which BU is "endemic", explaining why BU is reported merely in populations of Western European Ancestry (Spain, France, The Netherlands, Great Britain, but also non-european countries such as Puerto Rico). [9] Functional analysis of patient-derived immune cells revealed that ERAP2 increases the abundance of peptides that specifically bind to HLA-A29 and further supports that the antigen presentation pathway drives the etiology of BSCR.[10]

Diagnosis

Treatment

Birdshot chorioretinopathy may show resistance to treatment.

Immunosuppressant therapy along with oral corticosteroid has been somewhat effective in slowing down the progressive inflammation associated with the disorder, preserving visual integrity as much as possible. Long-term use of such medications must be closely monitored, however, due to the discomforting and potentially debilitating and life-threatening side-effects.[11][12]

Immunosuppressive drugs such as the

vitreous inflammation and retinal vasculitis have been evident via electroretinography, during daclizumab (IL-2 receptor blocker) therapy. This is also supported by the observation of elevated levels of IL-2 in the eyes of patients.[6] Loss of visual acuity unrelated to the inflammation caused by the disorder, however, often remains unchanged despite usage of the drug. This is reflected by the lack of difference in visual acuity and the vision-related quality of life among various treatment categories in birdshot patients.[13] Contraindications and adverse side-effects are always a factor, as well.[14]

A corticosteroid implant surgically placed within the eye can be used for patients who are not able to achieve remission on or tolerate immunomodulatory therapy, or in cases where this option presents less of a burden on life than long-term medical therapy.

References

  1. ^
    PMID 28314830
    .
  2. ^ RESERVED, INSERM US14 -- ALL RIGHTS. "Orphanet: Birdshot chorioretinopathy". www.orpha.net. Retrieved 2017-07-02.{{cite web}}: CS1 maint: numeric names: authors list (link)
  3. ^ "Birdshot chorioretinopathy | Genetic and Rare Diseases Information Center (GARD) – an NCATS Program". rarediseases.info.nih.gov. Archived from the original on 2018-03-04. Retrieved 2017-07-02.
  4. ^ "Birdshot Retinopathy: Background, Pathophysiology, Epidemiology". 2017-05-02. {{cite journal}}: Cite journal requires |journal= (help)
  5. PMID 10896989
    .
  6. ^
    PMID 21570674
    .
  7. PMID 24379648
    .
  8. PMID 24957906
    .
  9. PMID 33262772
    .
  10. PMID 33717175
    .
  11. PMID 15936442
    .
  12. S2CID 1554209
    .
  13. S2CID 6475153
    .
  14. PMID 18268208
    .

External links

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