Does Complement Factor H Gene Polymorphism Play a Role in the Regulation of Vascular Tone in the Choroid?

Study Overview
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Brief Summary
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Age related macular degeneration (AMD) is a multifactorial disease with a strong genetic component. Most importantly a genetic polymorphism in the gene encoding for the complement factor H (CFH) has been recently identified which is highly associated with an increased risk of developing AMD. This Tyr402His polymorphism located on chromosome 1q31 has been implicated to play a role in the development of the disease. Given that it is known that impaired regulation of choroidal vascular tone is present in patients with AMD, the current study seeks to investigate whether the Tyr402His polymorphism is associated with altered choroidal autoregulation in healthy subjects. For this purpose a total of 100 healthy volunteers will be included in order to test the hypothesis that an impaired regulation of choroidal blood flow is present in subjects with homozygous Tyr402His variant.

Official Title
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Does Complement Factor H Gene Polymorphism Play a Role in the Regulation of Vascular Tone in the Choroid?

Conditions
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Genetic Polymorphism, Macular Degeneration, Regional Blood Flow, Ocular Physiology

Intervention / Treatment
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* Procedure: Squatting


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Men and women aged between 18 and 35 years Nonsmokers Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant Normal ophthalmic findings, ametropy less than 3 diopters Exclusion Criteria: Regular use of medication, abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study Treatment in the previous 3 weeks with any drug Symptoms of a clinically relevant illness in the 3 weeks before the first study day Blood donation during the previous 3 weeks

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 45 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: 1<br>14 subjects homozygous HH for the Tyr402His single nucleotide polymorphism | Procedure: Squatting<br>* Squatting for 6 minutes<br>|
| Other: 2<br>14 subjects homozygous TT for the Tyr402His single nucleotide polymorphism | Procedure: Squatting<br>* Squatting for 6 minutes<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Choroidal blood flow during isometric exercise |  | 10 minutes | 
| Tyr402His genotyping |  | screening | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mean arterial pressure |  | 20 minutes | 
| Intraocular pressure |  | before and after blood flow measurements | 
| Systolic/diastolic blood pressure |  | 20 minutes | 
| Pulse rate |  | 20 minutes | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Age-related macular degeneration, Complement factor H, Choroidal blood flow