Prenatal chromosomal microarray analysis in foetuses with isolated absent or hypoplastic nasal bone

Area of Science:

• Prenatal Diagnosis
• Medical Genetics
• Fetal Ultrasound

Background:

• Isolated absent or hypoplastic nasal bone (NB) is a potential soft marker for chromosomal abnormalities in fetuses.
• Chromosomal microarray analysis (CMA) is a high-resolution technique for detecting chromosomal abnormalities.

Purpose of the Study:

• To evaluate the diagnostic efficiency of CMA in fetuses with isolated absent or hypoplastic NB.
• To determine the detection rate of chromosomal abnormalities and pathogenic copy number variations (CNVs) using CMA.

Main Methods:

• A retrospective analysis of 221 fetuses with isolated absent or hypoplastic NB who underwent invasive prenatal diagnosis and CMA.
• Data on gestational age at diagnosis and CMA results were collected and analyzed.

Main Results:

• CMA yielded a diagnostic rate of 9.0% (20/221), detecting aneuploidies in 5.9% and pathogenic CNVs in 3.2% of cases.
• No significant difference in detection rates was observed between absent and hypoplastic NB, or between first and second-trimester diagnoses.

Conclusions:

• CMA significantly increases the diagnostic yield for chromosomal abnormalities, particularly pathogenic CNVs, in fetuses with isolated absent or hypoplastic NB.
• CMA is recommended for prenatal diagnosis when isolated absent or hypoplastic NB is suspected antenatally.