title: NKX2.5 mutation identification on exome sequencing in a patient with heterotaxy.
abstract: Exome sequencing enables us to screen most of the protein coding genes in an unbiased way, this technique represents an ideal tool to identify previously under- or unappreciated phenotypes associated with known disease genes and genetic disorders. Here we present an illustrative case that required exome sequencing to identify a genetic alteration associated with the clinical features. The phenotype of the proband included heterotaxy, double outlet right ventricle, common atrioventricular canal, total anomalous pulmonary venous connection, asplenia, failure to thrive and short stature. Exome sequencing demonstrated a frameshift mutation c.397_400del (p.P133GfsTer 42) in NKX2.5. Although a single previous case of heterotaxy was reported in a large familial case of NKX2.5, heterotaxy is not clinically appreciated to be a part of the phenotypic spectrum associated with NKX2.5 mutations. This case report demonstrates the utility of exome sequencing in expanding a phenotypic spectrum of a known Mendelian disorder. We predict that this type of unexpected identification of mutations in known-disease associated genes in patients with atypical or expanded phenotypes will occur with increasing frequency as the use of exome and genome sequencing become more common tools in diagnosing patients with syndromic and non-syndromic foms of structural birth defects.
authors.affiliation: Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Research Center for Epigenetic Disease, Institute for Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan. Electronic address: kosukeizumi@iam.u-tokyo.ac.jp.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Izumi
authors.affiliation: Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Noon
authors.affiliation: Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.
authors.forename: Alisha
authors.initials: A
authors.lastname: Wilkens
authors.affiliation: Division of Human Genetics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; The Perelman School of Medicine at The University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: Ian D
authors.initials: ID
authors.lastname: Krantz
mesh_terms: D004252:DNA Mutational Analysis; D059472:Exome; D016368:Frameshift Mutation; D059446:Heterotaxy Syndrome / Q000235:genetics*; D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D000072576:Homeobox Protein Nkx-2.5; D018398:Homeodomain Proteins; C095552:NKX2-5 protein, human; D014157:Transcription Factors
keywords: Atrioventricular canal; Double outlet right ventricle; Intestinal malrotation