Data collection

In the GeoLynch study, the researchers collect information about diet and lifestyle and information on any tissue changes that may occur. This information will be collected through questionnaires, a blood sample and the results of the regular colonoscopy.

This research complies to the General Data Protection Regulation (GDPR).

What kind of data is collected?


For the GeoLynch study we are interested in the dietary habits and lifestyle of persons with Lynch syndrome. We collect this information through questionnaires, which are filled out by the participants at home. Participants are asked to fill out three questionnaires:

  1. a general questionnaire about health, family and lifestyle habits,
  2. a questionnaire about dietary habits,
  3. a questionnaire about any use of dietary supplements.

We also would like to determine the waist and hip circumference to get an indication of abdominal fat. In the general questionnaire participants are asked to write down their waist and hip circumference. The waist and hip circumference are measured by the participant with a tape measure, which has been included with the questionnaire.

Blood sample


After the GeoLynch participants have filled out the questionnaires we ask them to donate a blood sample. Blood sampling is carried out in cooperation with SHO Centres for Medical Diagnostics. Date and time for blood sampling is scheduled in consultation with the participant. We aim to use local polyclinics so that participants will not have to travel far. If the policlinic is too far away from a participants home, the SHO can plan an appointment for blood sampling at home. Participants do not have to fast before the blood sampling. For the blood sampling five small tubes of blood are collected, which will only take 5 to 10 minutes.

The blood samples will be analysed to determine concentrations of nutrients that may affect the development of tumours. Besides, the researchers will investigate the natural variation in DNA and the risk of developing tumours. For example, they will look at the effect of natural variation in DNA on the metabolism of nutrients in the body.

In order to store the blood for these analyses it has to be processed immediately. The blood samples are stored in a -80 ⁰C freezer until all the blood samples from all participants in the GeoLynch study have been collected. In this way all blood samples can be analysed at the laboratory at the same time.

The storage of blood for scientific research such as the GeoLynch study, is called a biobank. The definition of a biobank is: "a collection of biological samples and sometimes information about patients and/or healthy volunteers, which can be used for biomedical research." You can find general information about biobanking in the Netherlands at

Regular colonoscopy

Persons from Lynch syndrome families regularly undergo an intestinal examination, a colonoscopy. In this colonoscopy the mucous membrane of the colon is examined thoroughly for the presence of tumours. When a tumour is detected during a colonoscopy, the tissue of that tumour will be further examined by the medical specialist. 

In order to examine tissue alterations that precede the development of the tumour, DNA from tumour tissue will be analysed. The researchers will use the results from the regular colonoscopy for the GeoLynch study. Therefore, participants will not have to undergo an additional intestinal examination for this study.

If a participant does not undergo a colonoscopy any longer, that person can still participate in the GeoLynch study.