Fetal sex identification in maternal plasma by means of short tandem repeats on chromosome X

Gennaro Vecchione, Michela Tomaiuolo, Michelina Sarno, Donatella Colaizzo, Rosella Petraroli, Maria Matteo, Pantaleo Greco, Elvira Grandone, Maurizio Margaglione

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Analysis of fetal DNA in maternal plasma has recently been introduced as a new method for noninvasive prenatal diagnosis. In the majority of cases, the Y chromosome-specific sequences are commonly used as a fetus-specific marker with a high risk of false-negative cases. We attempted to develop a sensitive and reliable X chromosome short tandem repeat (STR) multiplex PCR amplification system that is suitable for the amplification of short-sized templates of free fetal DNA. Because of specific characteristics of fetal DNA in maternal plasma, cell-free fetal DNA is smaller than corresponding maternal DNA, and so we selected 10 X-STR loci in which the allele size was 250 bp. In addition, fetal sex was also investigated using the amelogenin gene in the same multiplex assay. Twenty-six women were enrolled in the study. Eight of 26 total fetuses analyzed were male and 18 were female. In the whole sample, X-STRs were informative with a mean of 4.84 ± 1.43. A mean of 2.67 ± 1.28 X-STR markers per sample (range 1-5) of paternally inherited fetal alleles were detected in pregnant women carrying a female fetus. In all cases, blind determination of fetal sex by means of the identification of amelogenin and X-STR markers was confirmed by fetal karyotyping. This study showed that this noninvasive technique is a reliable and accurate tool to investigate free fetal DNA in pregnancies within the first trimester and could be widely used in clinical research and diagnosis.

Original languageEnglish
Title of host publicationAnnals of the New York Academy of Sciences
Number of pages9
Publication statusPublished - 2008

Publication series

NameAnnals of the New York Academy of Sciences
ISSN (Print)00778923
ISSN (Electronic)17496632


  • Fetal sex
  • Maternal plasma
  • X chromosome short tandem repeat

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)


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