Phenotypically normal couples with recurrent pregnancies of trisomy 21 fetus: genetic analysis and literature review
10.3760/cma.j.cn113903-20240420-00298
- VernacularTitle:表型正常的夫妇反复妊娠21-三体胎儿的遗传学分析及文献复习
- Author:
Ju WANG
1
;
Hongmei ZHAI
;
Na LIU
;
Jin GU
;
Dongyi YU
Author Information
1. 青岛大学附属山东省妇幼保健院医学遗传与产前诊断中心（山东省医药卫生出生缺陷防治与遗传医学重点实验室，国家卫生健康委员会母胎医学重点实验室），济南 250014
- Keywords:
Recurrent pregnancy;
Trisomy 21;
Gonad mosaicism
- From:
Chinese Journal of Perinatal Medicine
2024;27(10):842-848
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the genetic causes in a phenotypically normal couple with three pregnancies of trisomy 21 offspring.Methods:A retrospective analysis was conducted on a phenotypically normal couple who had three pregnancies with trisomy 21 syndrome offspring and were transferred to Shandong Provincial Maternal and Child Health Care Hospital in December 2023. Genetic analysis was performed using quantitative fluorescence polymerase chain reaction (QF-PCR), karyotype analysis, chromosome microarray analysis (CMA), and fluorescence in situ hybridization (FISH). Relevant articles up to December 31, 2023, were retrieved from CNKI, Wanfang Database, Yiigle, and VIP using the terms "recurrent pregnancy", "consecutive pregnancy", "two pregnancies", and "trisomy 21 syndrome (Down syndrome)" in Chinese. Additionally, the English terms "recurrence or recurrent" "trisomy 21 syndrome" and "Down syndrome" were used to retrieve articles from PubMed, Embase, and Web of Science. The genetic causes of recurrent pregnancies with trisomy 21 syndrome fetuses were analyzed and summarized. Results:(1) Case from this hospital: Results of QF-PCR, karyotype analysis, and CMA of amniotic fluid cells in this pregnancy all indicated that the fetus had trisomy 21 syndrome. FISH tests on oral mucosal cells, decidual tissue, and urine sediment cells of the pregnant woman all indicated that she was a mosaic for trisomy 21. Additionally, QF-PCR detection of short tandem repeat (STR) loci on chromosome 21 suggested that there might be gonad mosaicism in the pregnant women, and an extra chromosome 21 in the fetus was derived from gonad mosaicism 21 trisomic cells. (2) Literature review: A total of 13 case reports with detailed records of recurrent pregnancy trisomy 21 syndrome history and related test results of both partners were retrieved, making a total of 14 cases, including seven cases each with a history of 2 and 3 trisomy 21 pregnancies. Translocation trisomy 21 was detected in each pregnancy of two cases. Of the 14 cases, five cases were only detected by peripheral blood samples of the couple, and the results were normal. The other nine cases were also detected by skin fibroblasts (six cases), ovarian tissue cells (two cases), oral mucosa cells (two cases), semen (two cases), and urinary sediment cells (one case), among which six cases indicated that one of the parents was chimeric trisomy 21, and five cases were female chimerism, one case was male chimerism. Only two cases were found to have mosaic trisomy 21 in peripheral blood sample, and the chimerism ratio was lower than that of other samples detected at the same time. In five cases, the extra chromosome 21 was found to be of maternal origin through testing of STR loci on chromosome 21.Conclusions:Parental mosaicism is an important cause of recurrent pregnancies with trisomy 21 syndrome. Testing samples from skin, oral mucosa, blood, semen, and ovaries can help detect low-level mosaicism.
