Chromosome Mosaicism

This information is useful for children, adults, and older adults
crowded streets, representing the number of people who may have mosaicism

Credit: Getty Images

Inside every cell in the human body is a nucleus that contains a person’s genetic information—his or her DNA—inherited from an egg cell and a sperm cell. When the fertilized egg begins to divide, it replicates its genetic material in cellular offspring. This cell replication builds and builds, creating tissues and organs in the body. In theory, each replicated cell should contain the exact same genetic information as the fertilized egg. However, this is not always the case. In rare instances, new genetic changes can occur in these replicated cells. These changes occur on the chromosomes, which are structures that look like sticks and carry all of a person’s genetic information, located in each cell’s nucleus. 

Until recently, scientists thought the condition was straightforward—either a person had mosaicism or not. As genetic sequencing technology becomes more sophisticated, a picture is emerging in the field of genetics showing that we all have some amount of mosaicism. The more frequently mosaicism is found in the body, the greater likelihood a person can develop a health condition because of it. 

“Every mosaic situation has to be treated individually,” says Saquib Lakhani, MD, clinical director of the Yale Medicine Pediatric Genomics Discovery Program (PGDP). “If a patient has a disease related to the mosaicism, it has to be managed and understood in the context of that particular disease.”

At Yale Medicine, our physicians work with the Yale Center for Genome Analysis and researchers to provide the best possible care for genetic-related diseases.