Systematic ultrasound evaluation of olfactory sulci in fetuses with congenital heart defects: a clue for CHARGE syndrome diagnosis.

Objectives: This study aimed to assess the role of olfactory sulci (OS) in diagnosing CHARGE syndrome among fetuses with major congenital heart defects (CHDs).

Methods: We prospectively evaluated OS development in fetuses diagnosed with CHDs from 2017 to 2021. Neurosonography (NSG) was performed using transabdominal and transvaginal approaches after 30 weeks of gestation. OS assessment was conducted in the trans-frontal coronal plane, classifying their appearance as fully developed, hypoplastic, or absent. Abnormal OS cases underwent MRI and trio-based clinical exome sequencing (CES).

Results: The study included 147 fetuses with CHD. Abnormal OS were found in 4 fetuses (2.7%) which also exhibited other additional anomalies. OS were absent in cases 1-3 and hypoplastic in case 4.. MRI confirmed OS abnormalities in all cases, and trio-based CES identified a CHD7 gene mutation in cases 1, 2, and 4, supporting the diagnosis of CHARGE syndrome. Case 3 had normal trio-based CES results. No other CHARGE syndrome cases were diagnosed postnatally among the cases with normal OS.

Conclusions: Systematic evaluation of OS in fetuses with major CHD might contribute to the diagnosis of CHARGE syndrome. Our findings support the inclusion of OS assessment in the prenatal evaluation of fetuses with major CHDs.