chapter_4 - Hereditary cancer syndromes family history as a...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
family history as a risk factor for cancer For certain types of cancer, a positive family history is a well-established risk factor for other relatives to develop the same disease. Important determinants of this risk are the age at diagnosis and the number of affected relatives: the more relatives and the younger they are at diagnosis, the higher the risk for other relatives is. Based on the estimated magnitude of this risk, screening guidelines can be provided to relatives in order to assure timely detection of malignancies. The more important types of cancer in which a family history is a risk factor are: s breast cancer s colorectal cancer s prostate cancer sporadic, familial and hereditary forms of cancer The contribution of the family history to the risk of healthy relatives to develop a particular cancer forms a continuum. The more relatives are affected and the younger their age at diagnosis, the higher the risk for unaffected relatives is and the higher the probability that there is a genetic predisposition to cancer in a family. Hereditary cancer syndromes are characterised by a Mendelian pedigree pattern. The annotation familial cancer is conserved for families in which cancer occurs more frequently than expected on the frequency in the general population but which lack a Mendelian pedigree pattern. Familial and hereditary forms of cancer are determined by different genetic factors. In familial cancer these are polymorphisms which influence the risk more moderately (e.g. in familial breast cancer: cumulative risk 15% to 30%). In these families, there probably also is a more important role for environmental factors. Hereditary tumours are caused by highly penetrant genetic defects - mutations (e.g. in hereditary breast cancer: cumulative risk >30%). In families in which these types of genetic aberrations segregate, environmental factors clearly play a less important role. hereditary cancer syndromes Hereditary cancer syndromes are characterized by the preferential occurrence of certain tumours in a family. The clinical spectrum of tumours to which relatives are predisposed is usually well-defined. All hereditary cancer syndromes are inherited autosomally, most of them are dominant. Genetic heterogeneity is a frequently encountered feature. The identification of genes involved in hereditary forms of cancer offers unprecedented possibilities in the genetic clinic and enables assessing whether relatives have inherited the pathogenic mutation which causes cancer to occur frequently in their family. Hereditary cancer syndromes
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
tumour suppressors & oncogenes Most of the genes involved in hereditary cancer syndromes are tumour suppressor genes. Both mutations in caretakers and gatekeepers have been identified. Caretakers encode genes that are involved in maintaining genome integrity, whereas gatekeepers directly interfere with fundamental processes such as cell cycle progression and apoptosis. MEN2 is one of the rare hereditary cancer syndromes that is caused by mutations in an oncogene.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 05/28/2010 for the course WE BIBI000000 taught by Professor Johangrooten during the Spring '10 term at Ghent University.

Page1 / 10

chapter_4 - Hereditary cancer syndromes family history as a...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online