Modern Pediatrics. Ukraine. (2023). 7(135): 113-121. doi: 10.15574/SP.2023.135.113
Dorosh O. I.^1,2, Dushar M. I.³, Sapuzhak M. V.¹, Pasichnyuk I. P.², Seredych L. P.¹, Mykh A. M.^1
1СNE of Lviv regional council “Western Ukrainian Specialized Pediatric Medical Centre”, Ukraine
²Danylo Halytsky Lviv National Medical University, Ukraine
³Laboratory center “Leogen”, Lviv, Ukraine

For citation: Dorosh OI, Dushar MI, Sapuzhak MV, Pasichnyuk IP, Seredych LP, Mykh AM. (2023). An (un)fortunate case as the impetus for the diagnosis of MYH9-related disease in a 16-year-old boy. Clinical case. Modern Pediatrics. Ukraine. 7(135): 113-121. doi: 10.15574/SP.2023.135.113.
Article received: Aug 25, 2023. Accepted for publication: Nov 18, 2023.

MYH9-related disease (MYH9-RD) is an autosomal dominant hereditary thrombocytopenia caused by mutations in the MYH9 gene with characteristic laboratory features – the presence of giant platelets and basophilic cytoplasmic inclusions in neutrophils (similar to Dele bodies). Patients with MYH9-RD are at high risk for deafness, cataracts, and renal dysfunction, most often occurring in adulthood. Platelet counts in patients with MYH9-RD range from severe thrombocytopenia to near-normal values, although they are usually stable. Propensity for hemorrhagic Complications correlate with platelet count and are usually absent or limited to minor bleeding in patients with mild thrombocytopenia, but may lead to spontaneous and potentially life-threatening bleeding with persistent platelet counts <50×10⁹/l.
Purpose – to describe a clinical case of a disease caused by a heterozygous mutation in the MYH9 gene with an emphasis on the importance of genetic tests for the final verification of the disease.
Clinical case. Features of diagnosis caused by a heterozygous mutation in the MYH9 gene in a 16-year-old boy are described. Throughout the child's life, the manifestations of the hemorrhagic syndrome were moderate (periodically a small number of bruises on the skin, to which the parents did not pay much attention, bleeding from the gums when brushing the teeth), the child’s blood tests were performed occasionally without determining the number of platelets. The boy suffered a displaced radius fracture as a result of the injury. The orthopedic traumatologist performed an operation of limited reposition of bone fragments followed by implantation of a needle for proper bone fusion without complications. During a general blood test, thrombocytopenia was detected, which prompted the child to be consulted by a hematologist. During the examination at the Western Ukrainian Specialized Pediatric Medical Center, Lviv, it was noted in the hardware count of the hemogram that the number of platelets was 22.0-30.0×10⁹/l, the microscopic count of platelets was 147.0-156.0×10⁹/l, the entire population of platelets was represented by macroforms with mean platelet volume 14.9 fl. We found good aggregation of platelets with ristocytin, and reduced aggregation with epinephrine, arachidonic acid, and adenosine. Verification of the final diagnosis of MYH9-RD caused by a heterozygous mutation in the MYH9 gene occurred by genome sequencing.
Therefore, the application of the genome sequencing technique can contribute to the early diagnosis of hereditary macrothrombocytopenia caused by a heterozygous mutation in the MYH9 gene.
The research was carried out in accordance with the principles of the Helsinki Declaration. The informed consent of the patient was obtained for conducting the studies.
No conflict of interests was declared by the authors.
Keywords: macrothrombocytopenia, heterozygous mutation in the MYH9 gene, genome sequencing, children.

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