Genetic analysis of a rare fetus with mandibulofacial dysostosis Guion-Almeida type.
Objective: To delineate the clinical and genetic features of a fetus with micrognathia, low-set ears, microtia, polyhydramnios and anechoic stomach by ultrasonography.
Methods: Whole exome sequencing (WES) was carried out to detect genetic variant in the fetus, for which routine chromosomal karyotyping and chromosomal microarray analysis (CMA) yielded no positive finding. Candidate variants were verified by Sanger sequencing and bioinformatic analysis.
Results: WES revealed that the fetus has carried a de novo nonsense c.2302C>T (p.Q768X) variant in exon 23 of the EFTUD2 gene, which was detected in neither parent. The variant was unreported previously and may lead to premature termination of the translation of EFTUD2 protein at the 768th amino acid. Bioinformatic analysis predicted the amino acid to be highly conserved and may alter the structure and function of the EFTUD2 protein.
Conclusion: The c.2302C>T variant of the EFTUD2 gene probably underlay the mandibulofacial dysostosis Guion-Almeida type in the fetus. Discovery of the novel variant has enriched variant spectrum of the EFTUD2 gene and provided a basis for genetic counseling and prenatal diagnosis for the family.