Chromosomal mosaicism in amniotic fluid cell cultures

Area of Science:

• Cytogenetics
• Prenatal Diagnosis
• Reproductive Medicine

Background:

• Chromosomal abnormalities detected during prenatal diagnosis can lead to complex clinical decisions.
• Distinguishing true fetal mosaicism from laboratory artifacts (pseudomosaicism) in amniotic fluid cultures is critical.
• In situ processing and colony-based analysis offer potential for improved diagnostic accuracy.

Purpose of the Study:

• To evaluate the incidence of chromosomal mosaicism in amniotic fluid cell cultures.
• To differentiate true mosaicism from pseudomosaicism using advanced culture techniques.
• To assess the clinical implications of mosaicism findings in prenatal genetic testing.

Main Methods:

• Analysis of 1,100 amniotic fluid samples over six years.
• In situ processing and colony selection for cytogenetic analysis.
• Confirmation of mosaicism in newborns or fetal tissues for true positive cases.

Main Results:

• Identified 32 cases of mosaicism out of 1,100 amniotic fluid samples.
• Confirmed two cases as true mosaicism (45,X/46,XX and 46,XX/47,XX,+21).
• Classified 29 cases as pseudomosaicism, with 12 showing a trisomy 2 line.

Conclusions:

• In situ processing and colony analysis are valuable for accurate mosaicism detection.
• The distinction between true mosaicism and pseudomosaicism is crucial for genetic counseling.
• These methods aim to minimize misdiagnosis risks associated with genetic amniocentesis.