title: A Turner syndrome neurocognitive phenotype maps to Xp22.3.
abstract: BACKGROUND
  Turner syndrome (TS) is associated with a neurocognitive phenotype that includes selective nonverbal deficits, e.g., impaired visual-spatial abilities. We previously reported evidence that this phenotype results from haploinsufficiency of one or more genes on distal Xp. This inference was based on genotype/phenotype comparisons of individual girls and women with partial Xp deletions, with the neurocognitive phenotype considered a dichotomous trait. We sought to confirm our findings in a large cohort (n = 47) of adult women with partial deletions of Xp or Xq, enriched for subjects with distal Xp deletions.
  
  
  METHODS
  Subjects were recruited from North American genetics and endocrinology clinics. Phenotype assessment included measures of stature, ovarian function, and detailed neurocognitive testing. The neurocognitive phenotype was measured as a quantitative trait, the Turner Syndrome Cognitive Summary (TSCS) score, derived from discriminant function analysis. Genetic analysis included karyotyping, X inactivation studies, fluorescent in situ hybridization, microsatellite marker genotyping, and array comparative genomic hybridization.
  
  
  RESULTS
  We report statistical evidence that deletion of Xp22.3, an interval containing 31 annotated genes, is sufficient to cause the neurocognitive phenotype described by the TSCS score. Two other cardinal TS features, ovarian failure and short stature, as well as X chromosome inactivation pattern and subject's age, were unrelated to the TSCS score.
  
  
  CONCLUSIONS
  Detailed mapping suggests that haploinsufficiency of one or more genes in Xp22.3, the distal 8.3 megabases (Mb) of the X chromosome, is responsible for a TS neurocognitive phenotype. This interval includes the 2.6 Mb Xp-Yp pseudoautosomal region (PAR1). Haploinsufficiency of the short stature gene SHOX in PAR1 probably does not cause this TS neurocognitive phenotype. Two genes proximal to PAR1 within the 8.3 Mb critical region, STS and NLGN4X, are attractive candidates for this neurocognitive phenotype.
authors.affiliation: Eugene McDermott Center for Human Growth and Development and Department of Internal Medicine, The University of Texas Southwestern Medical School, Dallas TX, USA. andrew.zinn@utsouthwestern.edu
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Zinn
authors.forename: David
authors.initials: D
authors.lastname: Roeltgen
authors.forename: Gerry
authors.initials: G
authors.lastname: Stefanatos
authors.forename: Purita
authors.initials: P
authors.lastname: Ramos
authors.forename: Frederick F
authors.initials: FF
authors.lastname: Elder
authors.forename: Harvey
authors.initials: H
authors.lastname: Kushner
authors.forename: Karen
authors.initials: K
authors.lastname: Kowal
authors.forename: Judith L
authors.initials: JL
authors.lastname: Ross