Prenatal diagnostic testing for familial dysautonomia using linked genetic markers

Area of Science:

• Genetics
• Medical Genetics
• Molecular Biology

Background:

• Familial dysautonomia (FD) is a rare, recessively inherited neurological disorder.
• The genetic locus for FD has been mapped to chromosome 9q31.
• Identifying at-risk pregnancies necessitates reliable diagnostic tools.

Purpose of the Study:

• To establish prenatal diagnostic methods for familial dysautonomia.
• To utilize genetic linkage and disequilibrium analyses for FD diagnosis.
• To assess the efficacy of polymorphic markers in predicting fetal status.

Main Methods:

• Linkage analysis using polymorphic dinucleotide repeat markers flanking the FD locus.
• Linkage disequilibrium analysis with marker D9S58 in families lacking proband DNA.
• Prenatal testing on eight fetuses across seven informative families.

Main Results:

• Prenatal diagnosis correctly identified all eight tested fetuses as heterozygous unaffected (FD carriers).
• Seven of these fetuses have been born and are healthy.
• A panel of six markers (three proximal, three distal) provides 87-96% predictive accuracy in the absence of recombination.
• One family with a 1:4 risk for FD underwent prenatal diagnosis indicating an affected fetus.

Conclusions:

• Prenatal diagnosis of familial dysautonomia is feasible and accurate using genetic markers.
• Linkage and linkage disequilibrium analyses with chromosome 9q31 markers are effective tools.
• Genetic testing provides vital information for families affected by familial dysautonomia.