Analysis of TUBB2B gene variant in a fetus with complex cortical dysplasia with other brain malformations-7 / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a fetus with dysgenesis of corpus callosum and other brain malformations.@*METHODS@#Whole exome sequencing was carried out for the fetus and its parents. Suspected pathogenic variants were verified by Sanger sequencing.@*RESULTS@#A novel de novo missense variant c.758T>A (p.L253Q) of the TUBB2B gene was identified, which was unreported previously. Based on the guidelines from the American College of Medical Genetics, the c.758T>A variant was predicted to be likely pathogenic. Bioinformatics analysis predicted that the leucine at position 253 was highly conserved among various species, and the c.758T>A variant may impact the formation of hydrogen bonds between Leu253 and Asp249 and Met257 residues, which in turn may affect the combination of GTP/GDP and function of the TUBB2B protein.@*CONCLUSION@#The c.758T>A variant of the TUBB2B gene probably underlay the fetal malformations in this Chinese family. Above discovery has enriched the spectrum of TUBB2B gene variants and provided a basis for genetic counseling and prenatal diagnosis.

Variation analysis of EPG5 gene in a Vici syndrome family / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic etiology of Vici syndrome in a Chinese family.@*METHODS@#Whole exome sequencing (WES) technology was used to detect gene variants in a fetus of abnormal ultrasonic structure without abnormalities in routine chromosome karyotype analysis and SNP-array. Sanger sequencing and bioinformatics prediction were performed for the suspected variants of the fetus and parents.@*RESULTS@#The fetus and the elder sister have carried c. 2427delC (p.T809fs) and c.1886A>T (p.E629V) compound heterozygous variants of the EPG5 gene, which were respectively inherited from their mother and father. Neither variant was reported previously. According to ACMG guidelines, the c.2427delC variant was predicted as pathogenic, while the c.1886A>T variant was of uncertain significance. PolyPhen-2 and PROVEAN software indicated that c.1886A>T variant was probably damaging.@*CONCLUSION@#The c.2427delC and c.1886A>T variants of the EPG5 gene probably underlie the pathogenesis of the Vici syndrome in this family. Above finding has enriched the variational spectrum of EPG5 gene and provided a basis for genetic counseling and prenatal diagnosis for the family.

Genetic analysis of a rare fetus with mandibulofacial dysostosis Guion-Almeida type / 中华医学遗传学杂志

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.