Analysis of L1CAM gene mutation and imaging appearance in three Chinese families with L1 syndrome: Three case reports

BACKGROUND: The molecular mutations of the L1CAM gene and the imaging appearances of four fetuses with L1 syndrome from three independent Chinese families with a history of hydrocephalus were reported in this study. Two of the three are novel L1CAM variants. METHODS: Results of clinical and imaging examinations of three Chinese families were collected. Fetal samples were collected by puncture, genomic DNA was extracted, whole‐exome sequencing was performed, and the L1CAM gene mutation sites were verified by PCR and Sanger sequencing. RESULTS: In this case report, we described the imaging appearance and investigated the mutations of the L1CAM gene in three Chinese families with a history of L1 syndrome; these included two nonsense mutations (c.262C>T and c.261C>G) and one splice‐site mutation (c.524‐1G>A). Two of these three are novel L1CAM variants: c.262C>T and c.261C>G. The results of the sonographic images of the affected fetuses showed severe hydrocephalus. Bilateral lateral ventricles were dilated in the fetuses with c.262C>T and c.261C>G mutations. The left ventricle was about 14 mm wide and the right was about 14 mm in the fetus with c.262C>T mutation. The left ventricle was about 24.9 mm wide and the right was about 23.9 mm in the fetus with c.261C>G mutation. The ultrasound examination of the fetus with c.524‐1G>A mutation showed that the third ventricle (7.5 mm wide) was raised, and the fourth ventricle was communicated with the cisterna magna. The parents requested termination of the above pregnancy. CONCLUSION: The current study emphasizes the importance of combining family history, prenatal ultrasonography, and L1CAM mutation testing positive for the diagnosis of the L1 syndrome.