Congenital thrombocytopenia associated with a heterozygous variant in the gene encoding a transcription factor essential for megakaryopoiesis.

The transcription factor MEIS1 (myeloid ectotrophic insertion site 1) is crucial for the maintenance of hematopoietic stem cells and for megakaryopoiesis. Germline variants in are associated with restless-leg syndrome, but were not previously shown to cause cytopenias. This is the first report of a patient with congenital thrombocytopenia associated with a sequence variant in , presenting with early onset severe thrombocytopenia and mild signs of bone marrow stress. Whole exome sequencing revealed a monoallelic splice site variant in , NM_002398.3:exon4:c.432 + 5 G > C, leading to a premature stop codon. We propose that heterozygous mutations in may cause congenital thrombocytopenia.