rs12340895

23andMe blog People with a rs12340895(G) (equivalent to rs12343867 in the study) had nearly four times higher odds of developing V617F-positive myelofibrosis (MPN) compared to people without the variant. "23andMe recently replicated this association, though we see a smaller effect — in our database, people with a G at rs12340895 have about two times the odds of developing V617F-positive MPN compared to people without the disease. People with an A at rs3780374 in the JAK2 gene (equivalent to rs4495487 reported in the study and highly correlated with rs12343867) have about three times higher odds of developing V617F-positive MPN compared to individuals without the A version." The following SNPs are (all) associated with the JAK2 46/1 haplotype that appears to predispose to V617F-positive neoplasms; since they are all part of one haplotype (and are not independent of one another), having one usually implies having the others as well. *rs12343867 *rs12340895 *rs3780374 *rs4495487 *rs10974944 For results applicable to those with Asian ancestry, use rs3780374. For results applicable to those with European ancestry, use rs12340895.

G;G

A Promethease user who has this rs12340895(G;G) genotype has reported that they have mastocytosis, a myeloproliferative neoplasm (MPN). But don't panic! Mastocytosis is listed as a rare disease by the Office of Rare Diseases (ORD) of the National Institutes of Health, which means mastocytosis affects less than 200,000 people in the entire US. To put it another way, 5 to 10 new cases are reported annually per million people. Since this rs12340895(G;G) genotype is carried by many people (e.g. ~10% of all Caucasians, or, over 30 million Americans), it's clear the overwhelming majority do not develop mastocytosis.