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Genomic landscape of colorectal carcinoma in sub-Saharan Africa
  1. Alessandro Pietro Aldera1,
  2. Komala Pillay1,2,
  3. Barbara Robertson3,
  4. Adam Boutall4,
  5. Rajkumar Ramesar5
  1. 1Division of Anatomical Pathology, University of Cape Town, Cape Town, South Africa
  2. 2Anatomical Pathology, National Health Laboratory Service, Groote Schuur Hospital, Cape Town, South Africa
  3. 3Division of Radiation Oncology, Groote Schuur Hospital and University of Cape Town, Cape Town, South Africa
  4. 4Division of Surgical Gastroenterology, Groote Schuur Hospital and University of Cape Town, Cape Town, South Africa
  5. 5UCT MRC Genomic and Precision Medicine Research Unit, Division of Human Genetics, Institute of Infectious Diseases and Molecular Medicine and University of Cape Town, Cape Town, South Africa
  1. Correspondence to Dr Alessandro Pietro Aldera, Division of Anatomical Pathology, Faculty of Health Sciences, University of Cape Town, Observatory, South Africa; alessandro.aldera{at}uct.ac.za

Abstract

Our understanding of the molecular classification of colorectal carcinoma (CRC) has evolved significantly over the past two decades. Tumours can be broadly categorised as microsatellite stable (MSS), microsatellite instability (MSI) or CpG island-methylator phenotype. Prognostic and predictive information is provided by these categories. The overwhelming majority of the data on which these categories are based have originated from Europe and North America. There is a dearth of information represented from Africa and indigenous African patients. However, some small studies and preliminary data have shown significant differences in all of these groups. The prevalence of MSI in Africa is consistently reported as almost double that of European and North American data. Interestingly, BRAF V600E mutations and MLH1 promotor hypermethylation seem to be uncommon in Africa. The high proportion of MSI tumours is only partly accounted for by germline mutations in mismatch repair genes (Lynch syndrome), suggesting that there are likely to be other mechanisms at play. Within the MSS group, preliminary data suggest that the typical molecular pathways (Wingless/Integrated pathway activation) may not be as dominant in Africa. The purpose of this review is to summarise the current state of the molecular genetic landscape of CRC in Africa and provide insights into areas for further study.

  • colorectal neoplasms
  • molecular biology
  • genetics

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Footnotes

  • Handling editor Runjan Chetty.

  • Contributors AA wrote the manuscript. RR provided supervision and guidance. All authors edited the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Map disclaimer The inclusion of any map (including the depiction of any boundaries therein), or of any geographic or locational reference, does not imply the expression of any opinion whatsoever on the part of BMJ concerning the legal status of any country, territory, jurisdiction or area or of its authorities. Any such expression remains solely that of the relevant source and is not endorsed by BMJ. Maps are provided without any warranty of any kind, either express or implied.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.