Table 4.

Detection of paternally and maternally inherited fetal highly polymorphic microsatellite markers in size-fractionated circulatory DNA obtained from maternal plasma samples obtained early in the second trimester.1

Case no. (D21 locus)Method of sample preparation2Maternal alleles detectedFetal alleles detected
1 (D21S1270)Maternal genomic DNA182/191
Fetal genomic DNA182/187/191
Total plasma DNA182/191Not detectable
Plasma DNA <300 bp182/191187
1 (D21S1432)Maternal genomic DNA133/141
Fetal genomic DNA133/137/141
Total plasma DNA133/141Not detectable
Plasma DNA <300 bp133/141137
2 (D21S1440)Maternal genomic DNA154
Fetal genomic DNA154/157
Total plasma DNA154Not detectable
Plasma DNA <300 bp154157
2 (D21S1435)Maternal genomic DNA141/172
Fetal genomic DNA172/176
Total plasma DNA141/172Not detectable
Plasma DNA <300 bp141/172176
3 (D21S1440)Maternal genomic DNA157/160
Fetal genomic DNA154/157
Total plasma DNA157/160Not detectable
Plasma DNA <300 bp157/160154/157
4 (D21S1440)Maternal genomic DNA154/157
Fetal genomic DNA157/160
Total plasma DNA154/157Not detectable
Plasma DNA <300 bp154/157160
  • 1 Four samples were analyzed in this study.

  • 2 Genomic DNA was prepared directly from maternal or fetal lymphocytes. “Total plasma DNA” indicates analysis of circulatory DNA extracted from an nonfractionated DNA samples, whereas “Plasma DNA <300 bp” indicates analysis of a discrete fraction of circulatory DNA that had been size-fractionated by gel electrophoresis.