title: Quantitative neurologic assessment of ataxia-telangiectasia.
abstract: BACKGROUND
  Ataxia telangiectasia (A-T) is a rare disorder with many distinctive neurologic features. Although there is substantial individual variation in the rate of progression of these features, their relationship to one another or to age has not been characterized.
  
  
  METHODS
  We formulated and tested multiple elements that assess different neurologic functions known to be affected by A-T. The overall index was applied to 52 patients with A-T, 2 to 29 years of age.
  
  
  RESULTS
  Seven elements items proved to be informative, and three elements were added based on face validity. In a linear regression model of individuals under 19 years of age, controlled for correlation within sibships, age accounted for 87% of the variation in the A-T Index.
  
  
  CONCLUSIONS
  Despite substantial individual variability of the phenotypic elements of A-T, scores on this multidimensional index have a very high correlation with age, indicating that there is a characteristic rate of progression of the disease, although functional domains in the brain are differentially affected. The pattern of scores suggests that a severe and a mild form of A-T may be distinguished by this quantitative measure. With further development this index may become useful as an outcome measure for treatment studies and prognosis.
authors.affiliation: Department of Neurology, Ataxia-Telangiectasia Clinical Center, the John Hopkins Medical Institutions, Baltimore, MD 21287-8811, USA.
authors.forename: T O
authors.initials: TO
authors.lastname: Crawford
authors.forename: A S
authors.initials: AS
authors.lastname: Mandir
authors.forename: M A
authors.initials: MA
authors.lastname: Lefton-Greif
authors.forename: S N
authors.initials: SN
authors.lastname: Goodman
authors.forename: B K
authors.initials: BK
authors.lastname: Goodman
authors.forename: H
authors.initials: H
authors.lastname: Sengul
authors.forename: H M
authors.initials: HM
authors.lastname: Lederman
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001260:Ataxia Telangiectasia / Q000175:diagnosis*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003627:Data Interpretation, Statistical; D018450:Disease Progression; D006801:Humans; D007223:Infant; D016014:Linear Models; D009483:Neuropsychological Tests; D015588:Observer Variation; D010641:Phenotype; D011237:Predictive Value of Tests; D011446:Prospective Studies; D015203:Reproducibility of Results; D012720:Severity of Illness Index