Twin anemia-polycythemia sequence in a case of monoamniotic twins.

Twin anemia-polycythemia sequence (TAPS) complicates up to 6% of monochorionic diamniotic twin pregnancies, typically in the late second or third trimester. The presence of only a few and very small arteriovenous vascular anastomoses characterizes the underlying angioarchitecture at the chorionic plate in cases of TAPS. In monoamniotic twins, large vascular anastomoses can usually be seen at the placental vascular equator, and therefore one would not expect the development of TAPS in monoamniotic twins. We report a case of TAPS in a monoamniotic pregnancy at 26 + 5 weeks' gestation which responded favorably to fetoscopic laser coagulation of the small placental anastomoses, resolving severe anemia in one twin and polycythemia in the other. The pregnancy continued until 32 + 5 weeks, when worsening cord entanglement with increased resistance and the development of postsystolic notches in the umbilical artery of one twin prompted delivery by Cesarean section. There was only a moderate difference in neonatal hemoglobin concentrations, with the former polycythemic twin needing a single partial volume exchange transfusion. The postnatal course of the neonates was uneventful, according to their gestational age at birth. To our knowledge this is the first case report describing successful laser therapy for TAPS in monoamniotic twins.

Gene transfer of SHIP-1 inhibits proliferation of juvenile myelomonocytic leukemia cells carrying KRAS2 or PTPN11 mutations.

Juvenile myelomonocytic leukemia (JMML) is a malignant disease of early childhood characterized by a hypersensitivity to granulocyte/macrophage colony-stimulating factor (GM-CSF). Mutations in RAS or PTPN11 are frequently detected in JMML patients. The SH2-containing inositol 5-phosphatase 1 (SHIP-1) is a negative regulator of GM-CSF signaling, and inactivation of SHIP-1 in mice results in a myeloproliferative disease. Here, we report the effects of SHIP-1 expression on GM-CSF-dependent proliferation and colony formation of human hematopoietic cells. After retroviral-mediated transduction of SHIP-1 into CD34+ cells from cord blood of healthy newborns or peripheral blood of JMML patients carrying mutations in KRAS2 or PTPN11, we observed a reduction in GM-CSF-dependent proliferation and colony formation. An enzymatically inactive form of SHIP-1 (D672A) had no effect. These data indicate that SHIP-1 can effectively block GM-CSF hypersensitivity in JMML progenitor cells with mutations in KRAS2 or PTPN11 and may be a useful approach for the treatment of JMML patients.