We studied induced-pluripotent stem cell (iPSC)-derived megakaryocytes (iMegs) to better understand these clinical disorders, beginning with iPSCs generated from a patient with PTSx and iPSCs from a control line with a targeted heterozygous <i>FLI1</i> knockout (FLI1<sup>+/-</sup>).
In this issue of Blood, Stevenson et al describe a family with a homozygous missense mutation in FLI1 that is associated with a platelet phenotype identical to the one observed in Paris-Trousseau syndrome, supporting existing evidence that FLI1 is directly involved in the mechanism of thrombocytopenia observed in this disease.
This kindred suggests abnormalities in FLI1 as causative of Paris-Trousseau thrombocytopenia and confirms the important role of FLI1 in normal platelet development.
Provocative new data suggest that FLI1 shows monoallelic expression during a brief window in megakaryocyte differentiation, which thus explains the dominant inheritance pattern of PTS despite the presence of one normal FLI1 allele.
In summary, this study documents ten new cases of PTS with characteristic alpha-granule abnormalities, and shows the putative pathogenic role of fli-1 gene in the pathophysiology of this syndrome.
We also show that dysmegakaryopoiesis in Fli-1 null embryos resembles that frequently seen in patients with terminal deletions of 11q (Jacobsen or Paris-Trousseau Syndrome).
A new congenital dysmegakaryopoietic thrombocytopenia (Paris-Trousseau) associated with giant platelet alpha-granules and chromosome 11 deletion at 11q23.
In summary, this study documents ten new cases of PTS with characteristic alpha-granule abnormalities, and shows the putative pathogenic role of fli-1 gene in the pathophysiology of this syndrome.
We also show that dysmegakaryopoiesis in Fli-1 null embryos resembles that frequently seen in patients with terminal deletions of 11q (Jacobsen or Paris-Trousseau Syndrome).
MYH10 was also detected in platelets of patients with the Paris-Trousseau syndrome, a thrombocytopenia related to the deletion of the transcription factor FLI1 that forms a complex with RUNX1 to regulate megakaryopoiesis, whereas MYH10 persistence was not observed in other inherited forms of thrombocytopenia.