title: Single-nucleotide polymorphism array genotyping is equivalent to metaphase cytogenetics for diagnosis of Turner syndrome.
abstract: OBJECTIVE
  Turner syndrome is a developmental disorder caused by partial or complete monosomy for the X chromosome in 1 in 2,500 females. We hypothesized that single-nucleotide polymorphism (SNP) array genotyping could provide superior resolution in comparison to metaphase karyotype analysis to facilitate genotype-phenotype correlations.
  
  
  METHODS
  We genotyped 187 Turner syndrome patients with 733,000 SNP marker arrays. All cases met diagnostic criteria for Turner syndrome based on karyotypes (60%) or characteristic physical features. The SNP array results confirmed the diagnosis of Turner syndrome in 100% of cases.
  
  
  RESULTS
  We identified a single X chromosome (45,X) in 113 cases. In 58 additional cases (31%), other mosaic cell lines were present, including isochromosomes (16%), rings (5%), and Xp deletions (8%). The remaining cases were mosaic for monosomy X and normal male or female cell lines. Array-based models of X chromosome structure were compatible with karyotypes in 104 of 116 comparable cases (90%). We found that the SNP array data did not detect X-autosome translocations (three cases) but did identify two derivative Y chromosomes and 13 large copy-number variants that were not detected by karyotyping.
  
  
  CONCLUSIONS
  Our study is the first systematic comparison between the two methods and supports the utility of SNP array genotyping to address clinical and research questions in Turner syndrome.
authors.affiliation: Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, Texas, USA.
authors.forename: Siddharth
authors.initials: S
authors.lastname: Prakash
authors.affiliation: Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, Texas, USA.
authors.forename: Dongchuan
authors.initials: D
authors.lastname: Guo
authors.affiliation: Division of Cardiovascular Medicine and the Heart Research Center, Oregon Health & Science University, Portland, Oregon, USA.
authors.forename: Cheryl L
authors.initials: CL
authors.lastname: Maslen
authors.affiliation: Division of Pediatric Cardiology, Oregon Health & Science University, Portland, Oregon, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Silberbach
authors.affiliation: Department of Internal Medicine, University of Texas Health Science Center at Houston, Houston, Texas, USA.
authors.forename: Dianna
authors.initials: D
authors.lastname: Milewicz
authors.affiliation: National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA.
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Bondy
mesh_terms: D000293:Adolescent; D000328:Adult; D041321:Chromosomes, Human, X; D041322:Chromosomes, Human, Y; D056915:DNA Copy Number Variations; D005260:Female; D014644:Genetic Variation; D060005:Genotyping Techniques; D006801:Humans; D018404:Isochromosomes; D007621:Karyotyping; D020411:Oligonucleotide Array Sequence Analysis; D020641:Polymorphism, Single Nucleotide; D012303:Ring Chromosomes; D014424:Turner Syndrome / Q000175:diagnosis* / Q000235:genetics