Genetics & Genomics

Mosaicism: Implications for Genetic Counseling and Medical Management

Laura Waldman

Suzanne M. Mahon
mosaicism, Li-Fraumeni syndrome, juvenile polyposis syndrome, genetic testing
CJON 2017, 21(4), 428-432. DOI: 10.1188/17.CJON.428-432

Mosaicism describes the presence of two or more populations of cells with different genotypes in one individual that have developed from a single fertilized egg. This article reviews the various clinical presentations of mosaicism associated with hereditary cancer syndromes and the challenges in providing patients and their families with appropriate genetic testing, as well as provides recommendations for cancer presentation and early detection. Management of mosaicism is based on personal and family history, along with genetic testing results.


  • Newer technologies and more widespread use of genetic testing have resulted in the detection of more cases of mosaicism.
  • Recommendations for care are made following careful review of the patient’s personal and family history and discussion with the laboratory; additional testing may be needed to further clarify the meaning of the results.
  • Oncology nurses should communicate with the genetics professional to obtain a clear understanding of the rationale behind the recommendations for care, as well as implications for testing in other family members, to ensure comprehensive care and psychosocial support for the patient and his or her family.
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