Babies with a common virus in the herpes family called congenital cytomegalovirus (CMV) may have an raised risk of developing acute lymphocytic leukemia (ALL), according to new research. The study also suggests the risk is raised further in Hispanic children.
It has long been conjectured that infection plays a role in childhood ALL, the most common form of childhood leukemia, but this is the first time researchers have tracked acute lymphocytic leukemia to a specific virus.
Lead study author Stephen Francis, PhD, assistant professor of epidemiology at the University of Nevada and University of California, San Francisco, said:
“Our goal in tracking CMV back from the time of diagnosis to the womb was to establish that this infection occurred well before initiation of disease."
The California Childhood Leukemia Study, from which investigators sourced the bone marrow samples, is based at UC Berkeley.
Researchers began by identifying all known infections present in the bone marrow of 127 children diagnosed with ALL and 38 children diagnosed with acute myeloid leukemia (AML). A state-of-the-art assay screened samples for all known viruses.
They detected congenital cytomegalovirus DNA in the bone marrow samples from children with ALL but rarely in those with AML.
Then, the scientists used an ultra-sensitive digital droplet screen to examine newborn blood samples for CMV from 268 children who went on to develop ALL. They compared the samples with healthy children (270). ALL typically develops in children between the ages of two and six.
The results show that children who went on to develop ALL are 3.71 times more likely to be CMV-positive at birth.
Additionally, grading by Hispanic ethnicity shows a 5.9-fold increased risk of ALL in Hispanics infected perinatally with CMV. This is important because Hispanics are at the highest risk for developing ALL.
Up to 80 percent of Americans are infected with CMV. The virus is normally dormant, causing few symptoms.
But during pregnancy the virus can flare up and be transmitted to the fetus, causing serious consequences such as birth defects and hearing loss in newborns.
“If it’s truly that in utero CMV is one of the initiating events in the development of childhood leukemia, then control of the virus has the potential to be a prevention target,” Dr. Francis said. “That’s the real take-home message."
Although the research is in the early stages, the team hopes these results will inspire more studies that will validate these findings and lead to the development of a CMV vaccine.
Stephen Starko Francis, Amelia D. Wallace, George A. Wendt, Linlin Li, Fenyong Liu, Lee W. Riley, Scott Kogan, Kyle M. Walsh, Adam J. de Smith, Gary V. Dahl, Xiaomei Ma, Eric Delwart, Catherine Metayer and Joseph L. Wiemels In utero cytomegalovirus infection and development of childhood acute lymphoblastic leukemia Blood 2016 :blood-2016-07-723148; doi: https://doi.org/10.1182/blood-2016-07-723148
Image: Human cytomegalovirus (HCMV) virus particle. Pete Jeffs, Wellcome Images.