Background. Hereditary bone marrow failure syndromes are a category of biologically different syndromes that can cause cytopenia in at least one hematopoietic cell lineage.

Case. We present a 29-week-old male infant who had a low Apgar Score, advanced delivery room resuscitation, widespread petechial rash, and ecchymoses at birth, without any dysmorphic features. Initial laboratory tests revealed bicytopenia (platelet count 7x10 3 /uL, hemoglobin of 3.9 g/dL, neutrophil 2.0x103 /uL) with findings of disseminated intravasculer coagulation (DIC). Imaging studies demonstrated accompanying left-sided congenital pulmonary airway malformation. On the second postnatal week pancytopenia occurred and the bone marrow findings were consistent with congenital amegakaryocytic thrombocytopenia. Further evaluations for differential diagnosis of pancitopenia were performed and the results of congenital viral infections, metabolic and immunologic tests were negative. While supportive treatments were in progress, haploidentical bone marrow transplantation (BMT) was performed from the father at 84th day due to unavailability of HLA-matched relative or nonrelative donor. Whole exome sequencing revealed a novel heterozygous frameshift variation (c.1242dupT [p. Thr538fs]) in exon 8 of the MECOM gene and validated by Sanger sequencing. No variation was detected in the parents genetic analysis.

Conclusions. In this report, we present a patient with congenital bone marrow failure successfully treated with haploidentic BMT and describe a novel, de novo pathogenic variant in MECOM gene.

Keywords: MECOM gene, congenital amegakaryocytic thrombocytopenia, neonate