© 2009 NHS National Genetics Education and Development Centre

Genetics and Genomics for Healthcarewww.geneticseducation.nhs.uk

Inherited Pre-disposition to Bowel CancerFamilial Adenomatous

Polyposis (FAP)

This PowerPoint file contains a number of slides that may be useful for teaching of genetics concepts.

You may use these slides and their contents for non-commercial educational purposes.

© 2009 NHS National Genetics Education and Development Centre

Genetics and Genomics for Healthcarewww.geneticseducation.nhs.uk

Familial Adenomatous Polyposis

This presentation includes:

The genetic development of familial cancer (2 hit hypothesis)• A pedigree showing FAP in a family• A clinical photograph of a piece of resected bowel with multiple

polyps• Two pedigrees used to assess risk and highlight which relatives are

‘at risk’ and need bowel screening• Surveillance/Screening for FAP

© 2009 NHS National Genetics Education and Development Centre

Genetics and Genomics for Healthcarewww.geneticseducation.nhs.uk

The genetic basis of the dominantly inherited familial cancer syndromes

An altered allele is inherited and is found in all body cells that contain genetic material. When the second (previously normal) allele of the gene pair becomes inactivated in a particular somatic cell, this can lead to loss of control of cell growth and unchecked cell proliferation.

Clone of cancer cells from this one cell

Inherited altered allele

Second allele of the pair becomes inactivated (somatic mutation)

© 2009 NHS National Genetics Education and Development Centre

Genetics and Genomics for Healthcarewww.geneticseducation.nhs.uk

Fig. 12.2 ©Scion Publishing LtdPhoto. courtesy of Medical Illustration, Manchester Royal Infirmary

Familial adenomatous polyposis coli

(a) Pedigree of the Xenakis family.

(b) Part of a surgically resected colon with polyps.

© 2009 NHS National Genetics Education and Development Centre

Genetics and Genomics for Healthcarewww.geneticseducation.nhs.uk

Martin’s family

d. 34yrs

Martin Suzanne

Jamie12

Sophie9

Alex5

36(colectomy @ 25) Who is at

risk?

© 2009 NHS National Genetics Education and Development Centre

Genetics and Genomics for Healthcarewww.geneticseducation.nhs.uk

Martin’s family

d. 34yrs

Martin Suzanne

Jamie Sophie Alex12 9 5

36(colectomy @ 25) Who is at

risk?

© 2009 NHS National Genetics Education and Development Centre

Genetics and Genomics for Healthcarewww.geneticseducation.nhs.uk

Surveillance for FAP

• Annual sigmoidoscopies from age 10 to 12.

• Colonoscopies once polyps detected.

• Surveillance of remaining gut following colectomy.

• http://www.nice.org.uk/nicemedia/pdf/CSGCCfullguidance.pdf

Is there an alternative? Genetic testing