Ding et al. (2004) reported a 3-generation Japanese family in which 8 of 16 members had thrombocythemia, with a platelet count more than 600 x 109/L. Bone marrow biopsies were normocellular and normoplastic, except for increased megakaryocytes.
In affected members of a Japanese family with autosomal dominant thrombocythemia, Ding et al. (2004) identified a heterozygous activating mutation in the MPL gene (159530.0010).
Moliterno et ... - Germline Mutation in the MPL Gene In affected members of a Japanese family with autosomal dominant thrombocythemia, Ding et al. (2004) identified a heterozygous activating mutation in the MPL gene (159530.0010). Moliterno et al. (2004) found that approximately 7% of African Americans are heterozygous for a single nucleotide substitution in the MPL gene, 1238G-T, which results in a lys39-to-asn substitution (K39N; 159530.0009). African Americans with the K39N polymorphism, which the authors designated MPL Baltimore, had a significantly higher platelet count than controls without the polymorphism (p less than 0.001) and reduced platelet protein MPL expression. Moliterno et al. (2004) concluded that K39N represents a functional MPL polymorphism and is associated with altered protein expression of the thrombopoietin receptor and a clinical phenotype of thrombocytosis. Although DNA was isolated from platelets or peripheral blood from most individuals in the study, K39N was also present in DNA obtained from buccal smears from 2 of the patients available for study. - Somatic Mutation in the MPL Gene Pardanani et al. (2006) identified a somatic mutation in the MPL gene (W515L; 159530.0011) in 4 unrelated patients with thrombocythemia.