Table 3.

Detection of paternally and maternally inherited fetal highly polymorphic microsatellite markers in size-fractionated circulatory DNA obtained from maternal plasma samples taken close to term.1

Case no. (D21 locus)Method of sample preparation2Maternal alleles detectedFetal alleles detected
1 (D21S11)Maternal genomic DNA232/234
Fetal genomic DNA228/232
Total plasma DNA232/234Not detectable
Plasma DNA <300 bp232/234228/232
1 (D21S1435)Maternal genomic DNA172/180
Fetal genomic DNA172/176
Total plasma DNA172/1801763
Plasma DNA <300 bp172/180172/176
2 (D21S1270)Maternal genomic DNA184/188
Fetal genomic DNA180/184
Total plasma DNA184/188Not detectable
Plasma DNA <300 bp184/188180/184
2 (D21S1432)Maternal genomic DNA138/152
Fetal genomic DNA134/138
Total plasma DNA138/1521343
Plasma DNA <300 bp138/152134/138
3 (D21S1435)Maternal genomic DNA168/176
Fetal genomic DNA168/172
Total plasma DNA168/1761723
Plasma DNA <300 bp168/176168/172
  • 1 Three 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.

  • 3 Minimal detection of paternally inherited allele.