Louann Lawrence, DrPH, Department of Medical Laboratory Sciences, Tarleton State University, Fort Worth was contacted by Mr. Tim Smith through the American Society for Clinical Laboratory Science Consumer Web Forum. Mr. Smith writes, “Hi, I am homozygous for the prothrombin G20210A mutation. This is said to be rare. I thought my case might be of interest to some researchers. I’ve survived two PEs and am now on warfarin. I also have atrial fibrillation. What fun! I’ve made it to age 66. Anyway, if anyone is interested, I will be happy to contribute my case.”
Thank you, Mr. Smith, for your offer, and if any of our participants take an interest, please contact [email protected] so that George can put you directly in touch with Mr. Smith. Homozygous prothrombin G20210A cases are rare, as the US allelic frequency is 1.0%, according to Chang MH, Lindegren ML, Butler MA, et al; CDC/NCI NHANES III Genomics Working Group. Prevalence in the United States of selected candidate gene variants: Third National Health and Nutrition Examination Survey, 1991–1994. Am J Epidemiol. 2009;169:54–66. The association of the heterozygous mutation with venous thromboembolic disease is weak, as documented in Segal JB, Brotman DJ, Necochea AJ, et al Predictive value of factor V Leiden and prothrombin G20210A in adults with venous thromboembolism and in family members of those with a mutation: a systematic review. JAMA. 2009;301):2472–85; and owing to its rarity, the VTE association of homozygous prothrombin G20210A has not been measured.