PRENATAL DIAGNOSIS OF DE NOVO SUPERNUMERARY MARKER CHROMOSOME ORIGINATED FROM CHROMOSOME 16 BY ARRAY-CGH

Area of Science:

• * Medical Genetics
• * Prenatal Diagnosis
• * Cytogenetics

Background:

• * Routine prenatal screening identified abnormal serum biochemistry in a 33-year-old pregnant woman at 19 weeks gestation.
• * Amniocentesis was performed for further genetic evaluation.

Observation:

• * A non-satellited, monocentric marker chromosome was identified in 50% of cultured amniocytes.
• * Parental karyotypes were normal, indicating the marker was de novo.

Findings:

• * Fluorescence in situ hybridization (FISH) and array comparative genomic hybridization (array-CGH) confirmed the marker chromosome originated from chromosome 16.
• * Post-mortem examination revealed dysmorphic features including low-set ears, exophthalmos, a depressed nasal bridge, large mouth and lips, and extremity posture anomalies.

Implications:

• * This case highlights the importance of advanced genetic testing for characterizing marker chromosomes.
• * The presence of a chromosome 16-derived marker was associated with significant dysmorphic findings and developmental abnormalities.
• * Genetic counseling and informed decision-making regarding pregnancy management are crucial in such complex cases.