Aim: To develop magnetic nanoparticles (MNPs) based on iron oxide for DNA isolation from blood cells for quantitative molecular genetic analyses of the V617F mutation in the Januskinase 2 (JAK2) gene. Materials and Methods: MNPs were synthesized by the coprecipitation method and coated with tetraethyl orthosilicate (TEOS). The size and shape of the complexes were estimated using transmission electron microscopy. Twenty blood samples from patients with myeloproliferative disorders were used for DNA isolation with the MNPs. DNA quality and compatibility for molecular genetic studies of the JAK2 V617F mutation were investigated by gel electrophoresis and real-time polymerase chain reaction (RT-PCR). Results: The average amount of DNA isolated from 150 μL of whole blood was 75.2 ng when MNPs were used and 72.5 ng when standard silica sorbent was used. There was no DNA damage observed after interaction with MNPs. RT-PCR demonstrated similar values for the JAK2 V617F mutant DNA ratios in the samples after DNA isolation with MNPs and by standard sorption on silica. Conclusions: MNPs with silicate capsules of sufficient thickness were obtained and the undesirable damaging effect of iron oxides on nucleic acids during isolation from cells were eliminated. Designed MNPs allow obtaining intact DNA for molecular genetic studies using the example of the JAK2 V617F for study.