Analysis of a child with X-linked intellectual disability due to a maternal de novo splicing variant of the PAK3 gene / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic etiology for a child with profound intellectual disabilities and obvious behavioral abnormalities.@*METHODS@#A male child who had presented at the Zhongnan Hospital of Wuhan University on December 2, 2020 was selected as the study subject. Peripheral blood samples of the child and his parents were collected and subjected to whole exome sequencing (WES). Candidate variant was verified by Sanger sequencing. Short tandem repeat (STR) analysis was carried out to determine its parental origin. The splicing variant was also validated in vitro with a minigene assay.@*RESULTS@#WES results revealed that the child had harbored a novel splicing variant of c.176-2A>G in the PAK3 gene, which was inherited from his mother. The results of minigene assay have confirmed aberrant splicing of exon 2. According to the guidelines from the American College of Medical Genetics and Genomics, it was classified as a pathogenic variant (PVS1+PM2_Supporting+PP3).@*CONCLUSION@#The novel splicing variant c.176-2A>G of the PAK3 gene probably underlay the disorder in this child. Above finding has expanded the variation spectrum of the PAK3 gene and provided a basis for genetic counseling and prenatal diagnosis for this family.

Analysis of clinical features and PAK1 gene variant in a child with epilepsy and global developmental delay / 中华医学遗传学杂志

OBJECTIVE@#To investigate the clinical phenotype and genetic basis of a child with epilepsy and global developmental delay.@*METHODS@#A child with epilepsy and global developmental delay who had visited West China Second University Hospital, Sichuan University on April 1, 2021 was selected as the study subject. Clinical data of the child were reviewed. Genomic DNA was extracted from peripheral blood samples of the child and his parents. Whole exome sequencing (WES) was carried out for the child, and candidate variant was verified by Sanger sequencing and bioinformatic analysis. A literature review was also carried out by searching databases such as Wanfang data knowledge service platform, China National Knowledge Infrastructure, PubMed, ClinVar and Embase to summarize the clinical phenotypes and genotypes of the affected children.@*RESULTS@#The child was a 2-year-and-2-month-old male with epilepsy, global developmental delay and macrocephaly. Results of WES showed that the child has harbored a c.1427T>C variant of the PAK1 gene. Sanger sequencing confirmed that neither of his parents has carried the same variant. Only one similar case had been recorded by the dbSNP, OMIM, HGMD, and ClinVar databases. No frequency for this variant among Asian population was available in the ExAC, 1000 Genomes, and gnomAD databases. Prediction with IFT, PolyPhen-2, LRT, Mutation Taster, and FATHMM online software suggested that this variant is deleterious to the function of encoded protein. Based on the Standards and Guidelines for the Interpretation of Sequence Variants: A Joint Consensus Recommendation of the American College of Medical Genetics and Genomics (ACMG), the PAK1 gene c.1427T>C variant was determined to be likely pathogenic.@*CONCLUSION@#The PAK1 gene c.1427T>C variant probably underlay the epilepsy and global developmental delay in this child, which has provided a reference for the clinical diagnosis and genetic counseling in children with similar disorders.

AKAP12 regulates vascular integrity in zebrafish

The integrity of blood vessels controls vascular permeability and extravasation of blood cells, across the endothelium. Thus, the impairment of endothelial integrity leads to hemorrhage, edema, and inflammatory infiltration. However, the molecular mechanism underlying vascular integrity has not been fully understood. Here, we demonstrate an essential role for A-kinase anchoring protein 12 (AKAP12) in the maintenance of endothelial integrity during vascular development. Zebrafish embryos depleted of akap12 (akap12 morphants) exhibited severe hemorrhages. In vivo time-lapse analyses suggested that disorganized interendothelial cell-cell adhesions in akap12 morphants might be the cause of hemorrhage. To clarify the molecular mechanism by which the cell-cell adhesions are impaired, we examined the cell-cell adhesion molecules and their regulators using cultured endothelial cells. The expression of PAK2, an actin cytoskeletal regulator, and AF6, a connector of intercellular adhesion molecules and actin cytoskeleton, was reduced in AKAP12-depleted cells. Depletion of either PAK2 or AF6 phenocopied AKAP12-depleted cells, suggesting the reduction of PAK2 and AF6 results in the loosening of intercellular junctions. Consistent with this, overexpression of PAK2 and AF6 rescued the abnormal hemorrhage in akap12 morphants. We conclude that AKAP12 is essential for integrity of endothelium by maintaining the expression of PAK2 and AF6 during vascular development.

Identification of a Novel Deletion Region in 3q29 Microdeletion Syndrome by Oligonucleotide Array Comparative Genomic Hybridization / 대한진단검사의학회지

BACKGROUND: The 3q29 microdeletion syndrome is a genomic disorder characterized by mental retardation, developmental delay, microcephaly, and slight facial dysmorphism. In most cases, the microdeletion spans a 1.6-Mb region between low-copy repeats (LCRs). We identified a novel 4.0- Mb deletion using oligonucleotide array comparative genomic hybridization (array CGH) in monozygotic twin sisters. METHODS: G-banded chromosome analysis was performed in the twins and their parents. Highresolution oligonucleotide array CGH was performed using the human whole genome 244K CGH microarray (Agilent Technologies, USA) followed by validation using FISH, and the obtained results were analyzed using the genome database resources. RESULTS: G-banding revealed that the twins had de novo 46,XX,del(3)(q29) karyotype. Array CGH showed a 4.0-Mb interstitial deletion on 3q29, which contained 39 genes and no breakpoints flanked by LCRs. In addition to the typical characteristics of the 3q29 microdeletion syndrome, the twins had attention deficit-hyperactivity disorder, strabismus, congenital heart defect, and gray hair. Besides the p21-activated protein kinase (PAK2) and discs large homolog 1 (DLG1) genes, which are known to play a critical role in mental retardation, the hairy and enhancer of split 1 (HES1) and antigen p97 (melanoma associated; MFI2) genes might be possible candidate genes associated with strabismus, congenital heart defect, and gray hair. CONCLUSIONS: The novel 4.0-Mb 3q29 microdeletion found in the twins suggested the occurrence of genomic rearrangement mediated by mechanisms other than nonallelic homologous recombination. Molecular genetic and functional studies are required to elucidate the contribution of each gene to a specific phenotype.