title: Congenital pancytopenia and absence of B lymphocytes in a neonate with a mutation in the Ikaros gene.
abstract: BACKGROUND
  Congenital pancytopenia is a rare and often lethal condition. Current knowledge of lymphoid and hematopoietic development in mice, as well as understanding regulators of human hematopoiesis, have led to the recent discovery of genetic causes of bone marrow failure disorders. However, in the absence of mutations of specific genes or a distinct clinical phenotype, many cases of aplastic anemia are labeled as idiopathic, while congenital immune deficiencies are described as combined immune deficiency.
  
  
  METHODS
  We describe the case of a 33-week gestation age male with severe polyhydramnios, hydrops, and ascites who was noted to be pancytopenic at birth. Bone marrow examination revealed a hypocellular marrow with absent myelopoiesis. An immune workup demonstrated profound B lymphopenia, near absent NK cells, and normal T cell number. Due to the similarity of the patient's phenotype with the IKAROS knockout mouse, studies were performed on bone marrow and peripheral blood to assess a potential pathogenic role of Ikaros.
  
  
  RESULTS
  DNA studies revealed a point mutation in one allele of the IKAROS gene, resulting in an amino acid substitution in the DNA-binding zinc finger domain. Functional studies demonstrated that the observed mutation decreased Ikaros DNA-binding affinity, and immunofluorescence microscopy revealed aberrant Ikaros pericentromeric localization.
  
  
  CONCLUSIONS
  Our report describes a novel case of congenital pancytopenia associated with mutation of the IKAROS gene. Furthermore, these data suggest a critical role of IKAROS in human hematopoiesis and immune development.
authors.affiliation: Division of Hematology Oncology, Department of Pediatrics, Children's Hospital of Alabama, Birmingham, Alabama 35233, USA. fgoldman@peds.uab.edu
authors.forename: Frederick D
authors.initials: FD
authors.lastname: Goldman
authors.forename: Zafer
authors.initials: Z
authors.lastname: Gurel
authors.forename: Duha
authors.initials: D
authors.lastname: Al-Zubeidi
authors.forename: Ari J
authors.initials: AJ
authors.lastname: Fried
authors.forename: Michael
authors.initials: M
authors.lastname: Icardi
authors.forename: Chunhua
authors.initials: C
authors.lastname: Song
authors.forename: Sinisa
authors.initials: S
authors.lastname: Dovat
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D001402:B-Lymphocytes; D001853:Bone Marrow / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D030342:Genetic Diseases, Inborn / Q000097:blood / Q000235:genetics* / Q000276:immunology / Q000473:pathology; D005865:Gestational Age; D006801:Humans; D051740:Ikaros Transcription Factor / Q000235:genetics*; D007231:Infant, Newborn; D007958:Leukocyte Count; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D038042:Myelopoiesis / Q000235:genetics / Q000276:immunology; D010198:Pancytopenia / Q000097:blood / Q000235:genetics* / Q000276:immunology / Q000473:pathology; D010641:Phenotype; D017354:Point Mutation; D016511:Severe Combined Immunodeficiency / Q000097:blood / Q000235:genetics* / Q000276:immunology / Q000473:pathology; D016335:Zinc Fingers / Q000235:genetics / Q000276:immunology
chemical_list: C497239:IKZF1 protein, human; C497238:Zfpn1a1 protein, mouse; D051740:Ikaros Transcription Factor