With only unspecific findings, no significant signs of dysplasia in the bone marrow cytology, a normal karyotype, and no mutations detected for the genes ASXL1, CBL, DMT3A, EZH2, JAK2, RUNX1, SF3B1, SRSF2, TET2, TP53, U2F1 or ZRSR2, a hematological disease, e.g., a myelodysplastic syndrome, could not be diagnosed. The gene discussed is SF3B1; the disease is myelodysplastic syndrome.