Following two rounds of community health screening in northeastern Pennsylvania for the JAK2 genetic marker, 19 (1.6 percent) of the 1,170 people tested were found to have this mutation. This is the first time large scale screening for this JAK2 genetic mutation has been done in the United States.

The frequency of the mutation in the general population is not known. The federal Agency for Toxic Substances and Disease Registry (ATSDR) conducted the screenings in partnership with the Pennsylvania Department of Health and Mt. Sinai School of Medicine.

The community health screening was done in response to recent studies that found an increased number of cases of polycythemia vera (PV) in Schuylkill, Luzerne, and Carbon counties in northeastern Pennsylvania. Participants were residents of these counties who volunteered to be screened. All persons who participated have been notified of their individual test results. Those with a positive test have been offered a referral for further medical evaluation by a local physician.

Since the JAK2 genetic marker was identified in 2004, studies have shown that this mutation is present in more than 90 percent of patients with PV. Patients with the related conditions essential thromboycytosis (ET) and primary myelofibrosis also can carry the mutation. Scientists do not yet know whether the mutation occurs in otherwise healthy people.

Five of the persons who tested positive had previously been diagnosed with PV or ET. Each of these persons was found to have moderate-to-high levels of the JAK2 mutation in their specimen. The other 14 persons who tested positive were found to have low levels of the JAK2 mutation. These persons have been invited to take part in a follow-up study to determine if the number of cells with the mutation increases over time. The follow-up study will also determine if the mutation can disappear altogether in persons with very low levels, something that has been seen with other genetic mutations of this type.

Scientists also do not know how prevalent the mutation is in the general population, or whether everyone who has the mutation will develop PV or a related blood disease. To help answer these questions, ATSDR is supporting work through the Geisinger Health System to determine how commonly the JAK2 mutation occurs in the general population outside the tri-county area. These findings will be used to evaluate the need for additional JAK2 testing in the community.

For more information about the PV investigation, visit the PV Web site at: http://www.atsdr.cdc.gov/sites/polycythemia_vera/.

ATSDR, a federal public health agency of the U.S. Department of Health and Human Services, evaluates the human health effects of exposure to hazardous substances.