Drusen in hereditary angioedema patients, aged 50 years and older.

C1-inhibitor plays a crucial part in suppressing the activity of the classical
pathway of the complement cascade. Inhibition of C1 prevents activation of
complement components 2 and 4 (C2 and C4) and so has several downstream effects
on the complement cascade. Different single-nucleotide polymorphisms in the
C1-inhibitor gene are associated with hereditary angioedema. Genotypic
variation in the C1-inhibitor gene also showed significant genotypic
association with age-related macular degeneration (AMD). A follow-up study
showed the absence of any association with AMD in two case-control studies. To
test this further, we will test HEA patients, aged 50 years and older for
drusen, a precursor of the disease and/or AMD itself.

What is the contribution of the different variations in the C1-inhibitor gene
to the disease AMD?

This is a cohort study of 15 HEA patients. The duration of the whole study is
approximately 1,5 - 2 hours for each subject.
Before visiting the clinic the subjects receive a questionnaire about lifelong
smoking habits, dietary habits, medical history, use of medication and family
history of AMD. During their visit to the clinic they first undergo Snellen
visual acuity measurement, ophthalmic examination and pupils are dilated with
1.0% tropicamide and 2.5% phenylephrine.
20 Minutes after pupil dilatation we take a venous blood sample for genomic DNA
extraction, make digital nonstereoscopic 30° color fundus photographs (Topcon
TRC 50IX digital fundus camera), a Spectralis Domain OCT and a Fluorescein
angiograph (Heidelberg Engineering Spectralis HRA2+OCT).

Before visiting the clinic the subjects receive a questionnaire at home, what
they will return on their visit to the clinic. During their visit of 1,5-2
hours they get an ophthalmic examination, venapunction, fundus photograph,
SD-OCT and a fluorescein angiograph. There are no direct benefits or great
risks for the subjects.