CASE REPORT Open Access Detection of complex deletions in chromosomes 13 and 21 in a fetus by noninvasive prenatal testing

Background: To detect complex fetal subchromosomal abnormalities by noninvasive prenatal testing (NIPT). Case presentation: After routine prenatal serum screening, the plasma of high-risk pregnant women were tested via NIPT, and the NIPT results were further validated by fetal karyotype analysis and array-based comparative genomic hybridization (aCGH) through amniocentesis. In addition, the chromosome karyotypes of the parents were also analyzed. NIPT results indicated subchromosomal abnormalities in chromosomes 13 and 21; aCGH results showed 22 Mb and 16 Mb deletions in 13 q31.3- q34 and 21q11.1- q21.3, respectively; and the fetal karyotype was 45,XX, der(13),-21. The maternal karyotype 46,XX,inv(9)(p12q13),t(13;21)(q31.3;q21.3) was abnormal, while the paternal karyotype showed no obvious abnormality. Conclusion: In this study, we successfully detected complex deletions in chromosomes 13 and 21 in a fetus using NIPT, and NIPT can provide effective genetic information for the detection of fetal subchromosomal abnormalities