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Multiplicity in polyp count and extracolonic manifestations in 40 Dutch patients with MYH associated polyposis coli (MAP)
  1. M Nielsen1,
  2. P F Franken2,
  3. T H C M Reinards1,
  4. M M Weiss1,
  5. A Wagner3,
  6. H van der Klift1,
  7. S Kloosterman1,
  8. J J Houwing-Duistermaat4,
  9. C M Aalfs5,
  10. M G E M Ausems6,
  11. A H J T Bröcker-Vriends,
  12. E B Gomez Garcia7,
  13. N Hoogerbrugge8,
  14. F H Menko9,
  15. R H Sijmons10,
  16. S Verhoef11,
  17. E J Kuipers12,
  18. H Morreau13,
  19. M H Breuning1,
  20. C M J Tops1,
  21. J T Wijnen1,
  22. H F A Vasen14,
  23. R Fodde2,
  24. F J Hes1
  1. 1Centre of Human and Clinical Genetics, Leiden University Medical Centre, Leiden, Netherlands
  2. 2Department of Pathology, Josephine Nefkens Institute, Erasmus University Medical Centre, Rotterdam, Netherlands
  3. 3Department of Clinical Genetics, Erasmus University Medical Centre, Rotterdam
  4. 4Department of Medical Statistics and Bioinformatics, Leiden University Medical Centre
  5. 5Department of Clinical Genetics, Academic Medical Centre, Amsterdam, Netherlands
  6. 6Department of Medical Genetics, University Medical Centre, Utrecht, Netherlands
  7. 7Department of Clinical Genetics, University Hospital, Maastricht, Netherlands
  8. 8Department of Human Genetics and Hereditary Cancer Clinic, University Medical Centre, Nijmegen, Netherlands
  9. 9Department of Clinical Genetics and Human Genetics, VU University Medical Centre, Amsterdam
  10. 10Department of Clinical Genetics, University Medical Centre, Groningen, Netherlands
  11. 11Family Cancer Clinic, Netherlands Cancer Institute, Amsterdam
  12. 12Department of Gastroenterology and Hepatology, Erasmus University Medical Centre, Rotterdam
  13. 13Department of Pathology, Leiden University Medical Centre, Leiden
  14. 14The Netherlands Foundation for the Detection of Hereditary Tumours, Leiden
  1. Correspondence to:
 Dr F J Hes
 Centre for Human and Clinical Genetics, LUMC, PO Box 9600, 2300 RC Leiden, Netherlands;


Objective: To investigate the contribution of MYH associated polyposis coli (MAP) among polyposis families in the Netherlands, and the prevalence of colonic and extracolonic manifestations in MAP patients.

Methods: 170 patients with polyposis coli, who previously tested negative for APC mutations, were screened by denaturing gradient gel electrophoresis and direct sequencing to identify MYH germline mutations.

Results: Homozygous and compound heterozygous MYH mutations were identified in 40 patients (24%). No difference was found in the percentage of biallelic mutation carriers between patients with 10–99 polyps or 100–1000 polyps (29% in both groups). Colorectal cancer was found in 26 of the 40 patients with MAP (65%) within the age range 21 to 67 years (median 45). Complete endoscopic reports were available for 16 MAP patients and revealed five cases with gastro-duodenal polyps (31%), one of whom also presented with a duodenal carcinoma. Breast cancer occurred in 18% of female MAP patients, significantly more than expected from national statistics (standardised morbidity ratio = 3.75).

Conclusions: Polyp numbers in MAP patients were equally associated with the attenuated and classical polyposis coli phenotypes. Two thirds of the MAP patients had colorectal cancer, 95% of whom were older than 35 years, and one third of a subset of patients had upper gastrointestinal lesions. Endoscopic screening of the whole intestine should be carried out every two years for all MAP patients, starting from age 25–30 years. The frequent occurrence of additional extraintestinal manifestations, such as breast cancer among female MAP patients, should be thoroughly investigated.

  • AFAP, attenuated familial adenomatous polyposis
  • APC, adenomatous polyposis coli
  • BER, base excision repair
  • CHRPE, congenital hypertrophy of the retinal pigment epithelium
  • CRC, colorectal cancer
  • DGGE, denaturing gradient gel electrophoresis
  • FAP, familial adenomatous polyposis coli
  • MAP, MYH associated polyposis
  • MSI, microsatellite instability
  • SMR, standardised morbidity ratio
  • MYH
  • MYH associated polyposis
  • polyposis
  • colorectal cancer

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  • Competing interests: none declared