Prenatal genetic diagnosis of a case with ring chromosome 13 / 中华医学遗传学杂志

OBJECTIVE@#To carry out cyto- and molecular genetic analysis for a fetus with a ring chromosome identified through non-invasive prenatal testing (NIPT).@*METHODS@#A pregnant woman presented at the Shengjing Hospital Affiliated to China Medical University on May 11, 2021 was selected as the study subject. Maternal peripheral blood sample was screened by NIPT, and G-banded chromosomal karyotyping was carried out on amniotic fluid and peripheral blood samples from the couple. The fetus and the pregnant woman were also subjected to genomic copy number variation sequencing (CNV-seq), chromosomal microarray analysis (CMA), and fluorescence in situ hybridization (FISH) assay.@*RESULTS@#NIPT result suggested that the fetus had monomeric mosaicism or fragment deletion on chromosome 13. G banded chromosomal analysis showed that both the fetus and its mother had a karyotype of 47,XX,der(13)(pter→p11::q22→q10),+r(13)(::p10::q22→qter::), whilst her husband had a normal karyotype. FISH has verified the above results. No abnormality was detected with CNV-seq and CMA in both the fetus and the pregnant woman.@*CONCLUSION@#The ring chromosome 13 in the fetus has derived from its mother without any deletion, duplication and mosaicism. Both the fetus and the pregnant woman were phenotypically normal.

Identification of a NFB responsive element within the dimethylarginine dimethylaminohydrolase 2 gene promoter / 中华医学遗传学杂志

<p><b>OBJECTIVES</b>To identify a NFB responsive element within the dimethylarginine dimethylaminohydrolase 2 gene (DDAH) promoter and demonstrate its role in DDAH2 transactivation.</p><p><b>METHODS</b>DDAH2 promoter was analyzed with software to identify potential binding sites of transcription factors. A series of truncated DDAH2 promoter luciferase reporter plasmids were constructed and transfected into human embryonic kidney derived HEK293 cells. Luciferase assays were carried out to analyze the activity of the promoter. Electrophoresis mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) were used to identify the NFB responsive element in vitro and in vivo. DDAH2 promoter luciferase reporter plasmid with mutated NFB site was constructed and transfected into cells, and its activity was compared with that of the wild-type plasmid.</p><p><b>RESULTS</b>Potential bindings sites of many transcription factors were found within the DDAH2 promoter. The transcription activity of the DDAH2 promoter was high, and -530 to -437 was a positive regulating region. -476 to -469 of the DDAH2 promoter was a NFB responsive element, to which NFB can specifically bind. Mutation of the NFB element could significantly decrease the DDAH2 promoter activity.</p><p><b>CONCLUSION</b>-476 to -469 of the DDAH2 promoter was a NFB responsive element and is important for the transactivation of DDAH2.</p>