title: SHROOM3 is a novel candidate for heterotaxy identified by whole exome sequencing.
abstract: BACKGROUND
  Heterotaxy-spectrum cardiovascular disorders are challenging for traditional genetic analyses because of clinical and genetic heterogeneity, variable expressivity, and non-penetrance. In this study, high-resolution SNP genotyping and exon-targeted array comparative genomic hybridization platforms were coupled to whole-exome sequencing to identify a novel disease candidate gene.
  
  
  RESULTS
  SNP genotyping identified absence-of-heterozygosity regions in the heterotaxy proband on chromosomes 1, 4, 7, 13, 15, 18, consistent with parental consanguinity. Subsequently, whole-exome sequencing of the proband identified 26,065 coding variants, including 18 non-synonymous homozygous changes not present in dbSNP132 or 1000 Genomes. Of these 18, only 4--one each in CXCL2, SHROOM3, CTSO, RXFP1--were mapped to the absence-of-heterozygosity regions, each of which was flanked by more than 50 homozygous SNPs, confirming recessive segregation of mutant alleles. Sanger sequencing confirmed the SHROOM3 homozygous missense mutation and it was predicted as pathogenic by four bioinformatic tools. SHROOM3 has been identified as a central regulator of morphogenetic cell shape changes necessary for organogenesis and can physically bind ROCK2, a rho kinase protein required for left-right patterning. Screening 96 sporadic heterotaxy patients identified four additional patients with rare variants in SHROOM3.
  
  
  CONCLUSIONS
  Using whole exome sequencing, we identify a recessive missense mutation in SHROOM3 associated with heterotaxy syndrome and identify rare variants in subsequent screening of a heterotaxy cohort, suggesting SHROOM3 as a novel target for the control of left-right patterning. This study reveals the value of SNP genotyping coupled with high-throughput sequencing for identification of high yield candidates for rare disorders with genetic and phenotypic heterogeneity.
authors.affiliation: Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229, USA.
authors.forename: Muhammad
authors.initials: M
authors.lastname: Tariq
authors.forename: John W
authors.initials: JW
authors.lastname: Belmont
authors.forename: Seema
authors.initials: S
authors.lastname: Lalani
authors.forename: Teresa
authors.initials: T
authors.lastname: Smolarek
authors.forename: Stephanie M
authors.initials: SM
authors.lastname: Ware
mesh_terms: D000483:Alleles; D001483:Base Sequence; D019521:Body Patterning; D002877:Chromosomes, Human; D055028:Comparative Genomic Hybridization; D019295:Computational Biology; D003598:Cytoskeletal Proteins / Q000235:genetics* / Q000378:metabolism; D059472:Exome; D005260:Female; D005820:Genetic Testing; D015894:Genome, Human; D059446:Heterotaxy Syndrome / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D006720:Homozygote; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA / Q000379:methods*; D054460:rho-Associated Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D003598:Cytoskeletal Proteins; C515852:ROCK2 protein, human; D054460:rho-Associated Kinases