« Molecular Genetics Of HD | Main | HD Prevalence By Population »
November 23, 2003
Prenatal Testing
For fetuses at 50% risk. Prenatal testing for HD is possible for fetuses at 50% risk using the same DNA-based techniques described in Molecular Genetic Testing . DNA can be extracted from fetal cells obtained by amniocentesis at 16-18 weeks' gestation* or chorionic villus sampling (CVS) at about 10-12 weeks' gestation. Requests for prenatal diagnosis of (typically) adult-onset diseases are difficult situations requiring careful genetic counseling. The continuation of pregnancies in which test results are positive becomes a significant issue because issues related to testing of at-risk asymptomatic children pertain.
For fetuses at 25% risk. Linkage analysis can be used in prenatal diagnosis for fetuses at 25% risk in "exclusion testing" in such a way that the genetic status of the at-risk parents is not revealed [Tyler et al 1990].
* Gestational age is expressed as menstrual weeks calculated either from the first day of the last normal menstrual period or by ultrasound measurements. Copyright© 1993-2003, All Rights Reserved
www.genetests.org
Children's Health System and University of Washington, Seattle
Posted by Dave at November 23, 2003 08:04 AM
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