We analyzed blood samples from more than 200 normal adults, and quantified their Hb F by cation‐exchange high‐performance liquid chromatography. In several subjects with slightly elevated Hb F (0.4–4.3%), we determined the ^Gγ levels in the Hb F and DNA sequence variations in the locus control region II and in the ^Gγ and ^Aγ promoters. About 25% of the ∼200 normal teenaged high school students had elevated Hb F; detailed analyses of some 20 students, selected at random, identified most as females with a homozygosity for the C→T variation at position ‐158 (^Gγ). One 11‐year‐old boy was heterozygous for the A→G change at position ‐161 (^Gγ); he and two of his relatives had ∼4% Hb F, high ^Gγ values, and a high level of (mainly) ^Gγ‐mRNA. Nearly 40 normal adults from Macedonia and from Georgia (mostly Caucasians) were tentatively identified as Swiss HPFH heterozygotes because slightly elevated Hb F levels were observed at least once. Many of these persons were heterozygous or homozygous for the C→T mutation at ‐158 (^Gγ), and a few carried a γ‐globin gene triplication. The C→T change appears to be an important factor predisposing the adult to increased Hb F production. Evidence suggests a gene dose effect in (mildly) anemic adults; however, other factors besides the C→T change at ‐158 (^Gγ), including factors not linked to the β‐globin region, may cause an increase in γ‐chain synthesis.

We have identified a valine-->methionine mutation at position 67 of the beta chain in the hemoglobin of a young Russian patient with severe hemolytic disease, anemia, splenomegaly, Heinz body formation, and continued requirement for blood transfusions despite an early splenectomy. Sequencing of amplified DNA readily identified a GTG-->ATG mutation at codon 67. The introduction of the larger methionine residue into the heme pocket, and the loss of the bonds between valine at beta 67 and the heme group, adequately account for the severe instability of Hb Alesha and the serious clinical condition of its carrier.

Childhood essential thrombocythemia (ET) is a rare chronic myeloproliferative disorder. The quality of life of ET patients may decrease as a result of ischemic and hemorrhagic complications of unclear origin. Our goal was to characterize the hemostatic system in children with ET. We genotyped and investigated blood samples from 20 children with ET in a prospective case series study using platelet aggregation, functional flow cytometry (FC) assay and standard clotting assays. Three children had a JAK2V617F mutation, 4 had mutations in CALR and 13 were triple-negative. Myelofibrosis in stage 1-2 was detected in 3 children. Three patients had bleeding episodes and seven had ischemic events. Aggregation in response to collagen, adenosine diphosphate, and ristomycin was decreased in all patients. In FC, significant changes in the whole patient group compared to the healthy children control group were decrease in the resting forward scatter and PAC1 binding (activated GPIIb/IIIa) level. For the activated platelets, dense granules release (by mepacrine), PAC1, and GPIIb/IIIa levels were significantly decreased. GPIb/V/IX, P-selectin, and phosphatidylserine levels manifested only moderate differences. Forward and side scatter changes in response to stimulation (representing shape change) and dense granules release were significantly lower in the 3 patients with bleeding than in the 17 patients without hemorrhage. Activated partial thromboplastin time was slightly prolonged, prothrombin index was slightly shortened and thrombin time was normal, while fibrinogen was mildly decreased in the ET patients. It could be concluded that the observed platelet function defects could be related to bleeding in ET, and be potentially used as a marker.