title: The utilization and outcome of diagnostic, predictive, and prenatal genetic testing for huntington disease in johannesburg, South Africa.
abstract: BACKGROUND
  Huntington disease (HD) is an autosomal dominant neurodegenerative disorder for which genetic counseling and testing are available in South Africa.
  
  
  OBJECTIVE
  The purpose of this study was to assess the utilization of the services available in Johannesburg for diagnostic, predictive, and prenatal genetic testing and counseling for HD and the characteristics of the patients who use them.
  
  
  METHODS
  A retrospective study was conducted using records of patients (n=287) who had genetic counseling and/or testing for HD through the Division of Human Genetics, National Health Laboratory Service and University of the Witwatersrand, Johannesburg, between January 1998 and December 2006. Age, gender, number of children, ethnicity, and test results were analyzed.
  
  
  RESULTS
  Of the 287 patients included in this study, 77% had diagnostic testing, 20% predictive, and 3% prenatal testing. In the diagnostic group, 47% of subjects tested positive for HD1 and 9% for HDL2 (all Black or of mixed ancestry). Altogether, 66.7% of subjects in the predictive group had testing and 39.5% were positive. In both groups, White subjects were overrepresented. In seven prenatal tests, three fetuses (including a set of twins) tested positive for HD and termination of pregnancy was requested.
  
  
  CONCLUSIONS
  The HD services for predictive and prenatal testing appear to be underutilized, especially by Black individuals, possibly because of lack of awareness among these individuals and among healthcare providers and/or a lower HD prevalence in this group. Recognition of and testing for HDL2 is important in South Africa's large Black population, and HD testing services cannot be considered complete unless testing for both HD1 and HDL2 are undertaken.
authors.affiliation: Division of Human Genetics, School of Pathology, University of the Witwatersrand and the National Health Laboratory Services, Johannesburg, South Africa.
authors.forename: Elaine B
authors.initials: EB
authors.lastname: Sizer
authors.forename: Tabitha
authors.initials: T
authors.lastname: Haw
authors.forename: Tina-Marié
authors.initials: TM
authors.lastname: Wessels
authors.forename: Jennifer G R
authors.initials: JG
authors.lastname: Kromberg
authors.forename: Amanda
authors.initials: A
authors.lastname: Krause
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005817:Genetic Counseling / Q000706:statistics & numerical data; D005820:Genetic Testing / Q000706:statistics & numerical data*; D006801:Humans; D006816:Huntington Disease / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011247:Pregnancy; D011296:Prenatal Diagnosis / Q000706:statistics & numerical data*; D015995:Prevalence; D011379:Prognosis; D012189:Retrospective Studies; D013019:South Africa / Q000453:epidemiology; D055815:Young Adult