Case report: A case report and literature review of complete trisomy 9

Abstract

Complete trisomy 9 is a rare and lethal chromosomal anomaly characterized by multisystem dysmorphism and central nervous system (CNS) malformations. This study presents a case of complete trisomy 9 with an unusual phenotypic association and investigates the genetic pathways involved in this chromosomal abnormality. Trisomy 9 leads to a wide range of organ abnormalities, and this research contributes to a better understanding of the phenotype associated with this rare aneuploidy. The literature on the phenotypes of fetuses with various systems affected by complete trisomy 9 was reviewed and summarized. Correct diagnosis and appropriate counseling based on the characteristics of previous reports of fetuses with trisomy 9 is essential in maternity care and clinical management. To provide guidance and help for clinical diagnosis, this study aimed to explore the clinical and genetic characteristics of trisomy 9 syndrome to improve clinicians' understanding of the disease.

Keywords: aneuploid; chromosomal disorder; complete trisomy 9; genetic counseling; prenatal diagnosis.

FIGURE 1

2D sonographic image of the fetus at 12⁺² weeks showing NT = 4.5 mm (vertical section).

FIGURE 2

(A) Results of karyotype analysis showed 47,XY,+9. (B) Chromosomal microarray results of the amniocyte indicated trisomy 9. (C) CNV-seq assay results of the placenta, fetal skin tissue, umbilical cord blood, kidney, and heart indicated trisomy 9.