Information concerning comprehensive analysis for hereditary cancer

Introduction

You have been referred to genetic counselling as hereditary cancer is suspected in yourself and/or in your family. For this reason, you have been offered comprehensive genetic analysis where your genetic material (genes) will be examined based on DNA isolated from a blood sample. This is a short description of the genetic analysis and how the result can affect you and your family if a pathogenic variant (mutation) is detected. If you have any further questions, you are always welcome to contact your genetic counsellor or the physician responsible for your course of treatment at the Department of Clinical Genetics.

Genetic analysis

We will examine and analyze a part of your genetic material (genes) from a blood sample. Humans have approximately 20,000 genes, and the genetic analysis that you are offered includes approximately 400 genes. All these genes are associated with an increased risk of cancer if one or more pathogenic variants (mutations) are detected. Not all the genes that will be analyzed, are related to the specific type(s) of cancer that you and/or your family have experienced. In general, no other genes, besides the approximately 400 genes related to cancer, are being examined. Consequently, the risk of finding pathogenic variants, that are associated with other diseases than cancer, is very small.

If a pathogenic variant is detected, a relevant surveillance program is offered depending on your age and sex.

It is importing to know that a comprehensive genetic analysis does not examine all genes but only the genes relevant to the type(s) of cancer that you/and or your family have experienced. If deemed relevant to examine more genes, you will be informed of this during the genetic counselling.

NGC consent to genetic analysis

When comprehensive genetic analysis has been agreed, a NGC (National Genome Center) consent form must be signed and data will be stored at the NGC national database. In the NGC consentform, you must decide whether you wish to receive feedback regarding potential incidental findings (also named secondary findings) meaning possible findings of pathogenic variants in genes related to other diseases than cancer. It could be regarding risk of hereditary cardiac diseases for example. However, the risk of detecting such findings at the analysis is very small, as the analysis focus on the 400 genes related to cancer. You must also decide if you want your genetic data to be included in future health research. If not, you must register with the National Database of Non-Consent to the Use of Tissue Samples for Scientific Purposes (Vævsanvendelsesregister).

You will be informed of the NGC consent form during your consultation at the Department Of Clinical Genetics. You are also able to watch a video ”Samtykke til omfattende genetisk analyse” at our webpage: Genetisk rådgivning (in Danish)

If a pathogenic variant is detected

In most cases, the result of the genetic analysis will be normal. However, if one or more pathogenic variants are detected, you will be informed by your physician/genetic counsellor as agreed and most often offered a follow-up consultation with a physician. At this consultation you will be informed in more detail about the pathogenic variant that has been detected, how it is inherited and whether you will be offered a surveillance program. In some cases, it will be possible to test your family members, and a plan will be made at the consultation regarding how to inform them.

Variants of unknown significance

In some cases, when performing a genetic analysis, one or more “variants of unknown significance” are detected. It can be difficult to determine if such a variant has a health-related impact or if it simply is a rare normal variant. In most cases, there is no reason for concern or need for further analysis. In some cases, additional laboratory analysis and blood samples may be necessary to evaluate whether the variant has an impact on your health. If such analysis is relevant, you will be informed by your physician/genetic counsellor.