Analysis of genetic variant in a fetus featuring pontocerebellar hypoplasia type 6 / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a fetus with cerebellar dysplasia and widened lateral ventricles.@*METHODS@#The couple have elected induced abortion after careful counseling. Skin tissue sample from the abortus and peripheral venous blood samples from both parents were collected for the extraction of genomic DNA, which was then subjected to whole exome sequencing. Candidate variant was verified by Sanger sequencing.@*RESULTS@#Prenatal ultrasonography showed increased nuchal translucency (0.4 cm) and widened lateral ventricles. Magnetic resonance imaging revealed infratentorial brain dysplasia. By DNA sequencing, the fetus was found to carry compound heterozygous variants c.1A>G and c.1564G>A of the RARS2 gene, which were inherited from its father and mother, respectively. Among these, c.1A>G was known to be pathogenic, but the pathogenicity of c.1564G>A was unreported previously. Based on the American College of Medical Genetics and Genomics guidelines, the c.1564G>A variant of RARS2 gene was predicted to be likely pathogenic(PM2+PM3+PP3+PP4).@*CONCLUSION@#The compound heterozygous variants c.1A>G and c.1564G>A of RARS2 gene contributed to the fetus suffering from pontocerebellar hypoplasia type 6, which expanded variant spectrum of RARS2 gene.

Identification of two novel variants of the PCCB gene in a pedigree affected with propionic acidemia / 中华医学遗传学杂志

OBJECTIVE@#To detect pathogenic variants in a pedigree affected with propionic acidemia (PA).@*METHODS@#The proband was subjected to high-throughput next-generation sequencing. Suspected variants were validated by Sanger sequencing of his family members. mRNA was extracted from peripheral blood lymphocytes from the proband's father in order to verify the impact of the splicing variant by RT-PCR combined with Sanger sequencing. The pathogenicity of the missense variant was predicted by using PolyPhen-2, Mutation Taster, SIFT, COBALT and HOPE software.@*RESULTS@#The proband was found to harbor compound heterozygous variants of the PCCB gene, namely c.184-2A>G and c.733G>A (p.G245S), which were respectively inherited from his father and mother. RT-PCR combined with Sanger sequencing confirmed skipping of exon 2 during transcription. Bioinformatic analysis indicated the c.733G>A (p.G245S) variant to be damaging.@*CONCLUSION@#The two variants of the PCCB gene probably underlay the disease in this patient. Above findings have enriched the spectrum of PCCB gene variants.

Genetic variant analysis of a pedigree affected with lymphedema-distichiasis syndrome / 中华医学遗传学杂志

OBJECTIVE@#To analyze FOXC2 gene variant in a family affected with lymphodema-distichiasis syndrome (LDS).@*METHODS@#Peripheral blood samples were collected for the extraction of DNA and protein. Whole-exome sequencing was carried out to detect variants in the proband. Suspected variant was validated by Sanger sequencing. Western blotting was used to detect changes in protein expression.@*RESULTS@#The proband and his mother were both found to carry a heterozygous nonsense variant c.177C>G (p.Tyr59X) of the FOXC2 gene, which was previously unreported. Down-regulated expression of FOXC2 was detected by Western blotting. Prenatal ultrasonography of the fetus indicated increased nuchal thickness. Amniocentesis was performed at 21+1 weeks of pregnancy, genetic testing suggested that the fetus also carried the c.177C>G variant.@*CONCLUSION@#The patients' condition may be attributed to the heterozygous nonsense variant c.177C>G of the FOXC2 gene, which resulted in a significant decrease in FOXC2 expression. Increased nuchal thickness may also be related with decreased FOXC2 expression. Above finding has expanded the variant spectrum of the FOXC2 gene.

Identification of a Tp63 gene variant in an abortus with Ectrodactyly, Ectodermal dysplasia, Cleft lip/palate syndrome by whole-exome sequencing / 中华医学遗传学杂志

OBJECTIVE@#To detect potential variant in a male fetus suspected for Ectrodactyly, Ectodermal dysplasia, Cleft lip/palate (EEC) syndrome.@*METHODS@#Peripheral blood samples of the fetus and his parents were collected for the extraction of DNA. Whole-exome sequencing was carried out to detect potential variants. Suspected variants were verified by Sanger sequencing.@*RESULTS@#The fetus was found to carry a heterozygous c.673C>T missense variant of the Tp63 gene, which was known to underlie split-hand/split-foot malformation. The same variant was not found in either parents.@*CONCLUSION@#The heterozygous c.673C>T missense variant of the Tp63 gene probably underlies the EEC syndrome in the fetus. Above finding also expanded the phenotypic spectrum for this variant.