2023 ACMG Annual Clinical Genetics Meeting Digital Edition: Poster Gallery-Murky Waters: Discrepant Preimplantation Genetic Testing - Aneuploidy, Non-Invasive Prenatal Testing, and Prenatal Diagnostic Testing for Mosaic Trisomy 21

Murky Waters: Discrepant Preimplantation Genetic Testing - Aneuploidy, Non-Invasive Prenatal Testing, and Prenatal Diagnostic Testing for Mosaic Trisomy 21

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This case report discusses the challenges and importance of following recommended screening and testing guidelines in pregnancies following normal Preimplantation Genetic Testing - Aneuploidy (PGT-A) results. The case involves a 37-year old female patient who underwent in vitro fertilization (IVF) using a previously frozen embryo with normal PGT-A results. However, her non-invasive prenatal testing (NIPT) for trisomy 21 came back abnormal, leading to further testing.<br /><br />First trimester ultrasound showed normal nuchal translucency and a present nasal bone. The patient opted for both chorionic villus sampling (CVS) and amniocentesis. The CVS fluorescent in-situ hybridization (FISH) was consistent with trisomy 21, but the CVS chromosome analysis was normal. The CVS FISH results were later determined to be mosaic for trisomy 21, and the CVS microarray indicated mosaic trisomy 21 and confined placental mosaicism. The amniocentesis FISH was positive for trisomy 21, and both the chromosome analysis and microarray were consistent with mosaic trisomy 21.<br /><br />Throughout the testing process, the patient and her partner struggled to comprehend the discrepant results due to the high confidence of the PGT-A report. Psychosocial counseling was provided, and the couple ultimately decided to terminate the pregnancy following the amniocentesis results.<br /><br />The case highlights the importance of following recommended screening and testing guidelines, even after normal PGT-A results. Patients may mistakenly perceive PGT-A as eliminating the risk of chromosome abnormalities rather than reducing it. Confirmatory testing is recommended to provide additional information regarding the fetal chromosomal status.<br /><br />Overall, this case emphasizes the need for proper counseling, mental health support, and additional prenatal screening and diagnostic testing options to ensure accurate and informed decision-making in IVF pregnancies following normal PGT-A results.

Asset Subtitle

Presenting Author - Jennifer Dickerson, MS;

Meta Tag

Cell free DNA/cfDNA

Chromosomal Abnormalities

FISH

Microarray

Noninvasive prenatal screening (NIPS)

Preimplantation Diagnosis

Prenatal Diagnosis

Psychosocial Counseling Issues

Presenting Author Jennifer Dickerson, MS

Keywords

Preimplantation Genetic Testing - Aneuploidy

PGT-A

screening guidelines

testing guidelines

pregnancies

non-invasive prenatal testing

NIPT

trisomy 21

chorionic villus sampling

CVS