No abstract

No abstract

No abstract

Background: Tetrasomy 18p syndrome is a very rare chromosomal disorder that is caused by the presence of isochromosome 18p.Most tetrasomy 18p cases are de novo cases,maternal origin trisomy 18p is a very rare condition.At present, only 4 cases of maternal origin trisomy 18p have been reported.This was the the fifth from maternal trisomy 18p,the mother has no apparent disease phenotype.Case presentation: We hereby report a case of a fetus with normal ultrasound features, the Karyotyping and Single Nucleotide Polymophism array (SNP array) confirmed tetrasomy 18p.The mother and grandfather are phenotypically normal and healthy,but with trisomy 18p was confirmed by conventional karyotyping and SNP array.Conclusions: We report a family with an 18p trisomic mother and grandfather,18p tetrasomic fetus,the mother and grandfather are phenotypically normal. The findings could provide a reference for the genetic counseling of trisomy

This study explored the diagnostic efficiency of different prenatal diagnostic approaches for women with positive non-invasive prenatal screening (NIPS) results by analyzing their clinical information and pregnancy outcomes. We collected data on 626 NIPS-positive pregnant women from January 2017 to June 2021 and arranged subsequent prenatal diagnostic operations for them after genetic counseling, along with long-term intensive follow-up. A total of 567 women accepted invasive prenatal diagnosis (IPD) (90.58%), and 262 cases were confirmed as true positives for NIPS. The positive predictive values for trisomies 21 (T21), 18 (T18), and 13 (T13); sex chromosome aneuploidies (SCAs); rare autosomal trisomies (RATs); and microdeletion and microduplication syndromes (MMS) were 81.13%, 37.93%, 18.42%, 48.83%, 18.37%, and 41.67%, respectively. Discordant results between NIPS and IPD were observed in 48 cases, with the discordance rate being 8.47%. Additionally, there were 43 cases with discordant results between karyotyping and chromosomal microarray analysis (CMA)/copy number variation sequencing. Additional reporting of RATs and MMS with routine NIPS that only detects T21/T18/T13 and SCAs can yield more accurate diagnoses. However, NIPS cannot be used as a substitute for IPD owing to its high false positive rate and discordance with other diagnostic methods. Therefore, we recommend CMA combined with karyotyping as the preferred method for accurately diagnosing NIPS-positive women.