[Clinical phenotype and genetic analysis of a fetus with recombinant chromosome 8 syndrome].

OBJECTIVE: To explore the clinical characteristics and molecular genetic mechanism of a fetus with recombinant chromosome 8 (Rec8) syndrome. METHODS: A fetus who was diagnosed with Rec8 syndrome at the Provincial Hospital Affiliated to Shandong First Medical University on July 20, 2021 due to high risk for sex chromosomal aneuploidy indicated by non-invasive prenatal testing (NIPT) (at 21st gestational week) was selected as the study subject. Clinical data of the fetus was collected. G-banded karyotyping and chromosomal microarray analysis (CMA) were carried out on the amniotic fluid sample. Peripheral blood samples of the couple were also subjected to G banded karyotyping analysis. RESULTS: Prenatal ultrasonography at 23rd gestational week revealed hypertelorism, thick lips, renal pelvis separation, intrahepatic echogenic foci, and ventricular septal defect. The karyotype of amniotic fluid was 46,XX,rec(8)(qter→q22.3::p23.1→qter), and CMA was arr[GRCh37]8p23.3p23.1(158049_6793322)×1, 8q22.3q24.3(101712402_146295771)×3. The karyotype of the pregnant woman was 46,XX,inv(8)(p23.1q22.3), whilst that of her husband was normal. CONCLUSION: The Rec8 syndrome in the fetus may be attributed to the pericentric inversion of chromosome 8 in its mother. Molecular testing revealed that the breakpoints of this Rec8 have differed from previously reported ones.

[Result of prenatal diagnosis for 151 high-risk women by noninvasive prenatal screening based on high-throughput sequencing].

OBJECTIVE: To assess the value of combined fetal karyotyping and chromosomal microarray analysis (CMA) for the verification of high-risk pregnancy signaled by noninvasive prenatal screening (NIPS) based on high-throughput sequencing. METHODS: One hundred and fifty-one pregnant women with high risks for aneuploidies of chromosomes 13, 18, 21, X and Y or pathological copy number variations (CNVs) by NIPS were subjected to amniocytic karyotyping and CMA analysis. RESULTS: One hundred and forty-two women were found to have a high risk for fetal chromosomal aneuploidies, which included 83 cases of trisomy 21, 17 cases of trisomy 18, 2 cases of trisomy 13, and 40 cases of sex chromosome aneuploidies. Amniocytic karyotyping and CMA analysis has confirmed 81 cases of trisomy 21, 15 cases of trisomy 18, 10 cases of 47,XXY, 4 cases of 47,XXX, 2 cases of 47,XYY and 1 case of 46,X,del(X)(q26.1). Two trisomy 21, two trisomy 18, 2 trisomy 13, and 23 cases of sex chromosomal aneuploidies were verified as false positives. For 9 women with pathological fetal CNVs detected by NIPS, combined fetal karyotyping and CMA has confirmed 1 case of chromosome 13 microdeletion, 1 case of chromosome 18 microduplication, and 1 case of chromosome 18 deletion. For a case with 30 Mb duplication of chromosome 2 and 25 Mb duplication of chromosome 8, CMA analysis had no positive finding, while fetal umbilical cord blood karyotyping has yielded a 46,XX,dup(2)(p23.1p25.3)[13]/46,XX[87] karyotype. The remaining 5 cases were confirmed as false positive results. CONCLUSION: Combined fetal karyotyping and CMA has provided a powerful tool for verifying high-risk fetuses signaled by NIPS.