Genetic analysis of a Chinese pedigree with Cohen syndrome due to compound heterozygous variants of VPS13B gene / 中华医学遗传学杂志

OBJECTIVE@#To investigate the clinical phenotype and genetic characteristics of a Chinese pedigree affected with Cohen syndrome.@*METHODS@#A proband who was admitted to Zhengzhou People's Hospital on June 2, 2021 due to intellectual disability and developmental delay, in addition with her younger sister and other family members, were selected as the study subjects. Clinical data of the proband and her younger sister were collected. Genomic DNA was extracted from peripheral venous blood and chorionic villi samples. Chromosomal abnormalities were detected with chromosomal microarray analysis (CMA). Whole exome sequencing (WES) and Sanger sequencing were carried out to detect candidate variants in the proband. With RNA extracted from the peripheral blood samples, VPS13B gene transcripts and expression were analyzed by PCR and real-time quantitative PCR. Prenatal diagnosis was carried out at 12 weeks' gestation.@*RESULTS@#The proband was a 10-year-old female with clinical manifestations including development delay, obesity, severe myopia and peculiar facial features. Her sister was 3 years old with a similar phenotype. CMA revealed no chromosomal abnormality in the proband, while WES results revealed that the proband and her sister had both harbored compound heterozygous variants of the VPS13B gene, namely c.10076_10077delCA (p.T3359fs*29) and c.6940+1G>T, which were respectively inherited from their mother and father. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), both variants were classified as pathogenic (PVS1+PS4+PM4+PP1; PVS1+PM2_Supporting+PM3+PP1). In vivo splicing assay confirmed that the c.6940+1G>T variant has produced a frameshift transcript with skipping of exon 38. Compared with the control group, the expression of RNA in the peripheral blood of the proband's parents has decreased to 65% ~ 70% (P < 0.01), whilst that in the proband and her sister has decreased to 40% (P < 0.001). Prenatal diagnosis at 12 weeks of gestation has found that the fetus only harbored the heterozygous c.10076_ 10077delCA variant.@*CONCLUSION@#The c.10076_10077delCA (p.T3359fs*29) frameshift variant and c.6940+1G>T splicing variant probably underlay the Cohen syndrome in this pedigree. Genetic testing has facilitated the diagnosis of this disease.

Expert consensus on the genetic diagnosis for Dystrophinopathies / 中华医学遗传学杂志

Dystrophinopathies, including Duchenne muscular dystrophy, Becker muscular dystrophy and dilated cardiomyopathy, are X-linked recessive genetic disorders due to variants of the dystrophin gene, which can seriously affect quality of life and health. Genetic diagnosis plays a crucial role in their diagnosis, treatment, and prevention. How to rationally select and standardize the use of various genetic techniques is a skill that clinicians must acquire. By compiling expertise of experts from the relevant areas and guidelines published home and abroad, this consensus has provided a guidance from the perspective of genetic diagnosis for the selection of genetic techniques, testing strategies, and detection process for dystrophinopathies.

Identification and analysis of anovel variant of TRAPPC2 in a X-linked spondyloepiphyseal dysplasia tarda pedigree / 中华骨科杂志

Objective:To provide experimental evidence for genetic counseling and prenatal diagnosis by analyzing the clinical characteristics, screening and identification of the function of suspicious variants in a X-1inked spondyloepiphyseal dysplasia tarda (SEDT) family.Methods:The family members' medical history, general physical examination, femur, spine X-ray examination were collected. Peripheral blood samples of the family members were collected and DNA was extracted from these samples. Sequencing clinical whole exons of proband DNA by targeted gene high-throughput sequencing method, then analysis sequencing data. The suspicious mutation was confirmed in pedigree members by PCR and Sanger sequencing. Reverse transcription polymerase chain reaction (RT-PCR) experiments of total RNA from blood lymphocytes were performed. The amplification of exons 3 and 4 of the pathogenic gene were amplified and identified by agarose gel. The expression of the pathogenic gene was also detected.Results:Three affected males of the family were diagnosed with SEDT according to their clinical and radiological features. A nonsense mutation in the transport protein particle complex subunit 2 ( TRAPPC2) gene NM_001011658: c.91A>T (p.K31*) was found in the proband using whole exome sequencing. This variation was also detected in his cousin, but not in non-phenotypic members of the family. The RT-PCR result for amplification of exon 3 and 4 of peripheral blood lymphocytes was the same as those of normal controls, indicating that the mutation did not affect the splicing of transcripts. qPCR results showed that the transcriptional expression of TRAPPC2 in patients was significantly lower than that in family normal controls and normal people controls. Conclusion:Identification of the novel nonsense mutation (c.91A>T) in the SEDT family enables early patients screening, carrier detection, genetic counseling, prenatal diagnosis, and clinical prevention and treatment. The detailed genotype/phenotype descriptions contribute to the SEDT mutation spectrum. The study of the function of TRAPPC2 mutation will help to further elucidate the role of sedlin in cartilage.

Analysis of CNTNAP1 gene variants in a Chinese pedigree affected with lethal congenital contracture syndrome type 7 / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a couple who had developed polyhydramnios during three pregnancies and given birth to two liveborns featuring limb contracture, dyspnea and neonatal death.@*METHODS@#Whole-exome sequencing (WES) was carried out on fetal tissue and peripheral blood samples from the couple. Suspected variants were verified by Sanger sequencing.@*RESULTS@#The fetus was found to harbor homozygous nonsense c.3718C>T (p.Arg1240Ter) variants of the CNTNAP1 gene, which were respectively inherited from its mother and father. The variant was unreported previously. According to the guidelines of the American College of Medical Genetics and Genomics, the variant was predicted to be pathogenic (PVS1+PM2+PP4).@*CONCLUSION@#The novel homozygous nonsense variants of the CNTNAP1 gene probably underlay the lethal congenital contracture syndrome type 7 (LCCS7) in this pedigree. Above finding has enabled genetic counseling and prenatal diagnosis for the family.

Analysis of a Chinese pedigree affected with dyschromatosis symmetrica hereditaria due to a novel variant of ADAR gene / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a Chinese pedigree affected with dyschromatosis symmetrica hereditaria (DSH).@*METHODS@#PCR and Sanger sequencing were carried out for the proband, and suspected variant was validated by Sanger sequencing in the pedigree.@*RESULTS@#The proband was found to harbor a novel variant of c.1352delA (p.N451Mfs*13) of the ADAR (NM_001111) gene. The same variant was found in her affected mother and sister, but not in her unaffected father, uncle, and 100 healthy individual.@*CONCLUSION@#The novel variant of the ADAR gene probably underlay the pathogenesis of DSH in this pedigree.

Research on prenatal genetic diagnosis of fetal renal cystic disease / 中华肾脏病杂志

Objective:To summarize the diagnosis features of the prenatal genetic diagnosis of fetal renal cystic disease and to explore the clinical feasibility and significance of prenatal genetic diagnosis of congenital cystic nephrosis.Methods:A total of 25 fetuses with congenital renal cystic disease were examined via invasive prenatal diagnosis in Henan Provincial People's Hospital from June 2017 to September 2019. Amniotic fluid samples were extracted by amniocentesis. Chromosomal microarray analysis (CMA) were performed in 17 cases. In addition to CMA, the other 8 cases were analyzed by G-band karyotype. Whole exome sequencing (WES) was performed in 6 cases which got normal results by CMA and karyotype, and highly suspected as hereditary disease.Results:Of the 25 fetuses assessed, 4 cases (16.0%) pathogenic copy number variation (pCNV) were found, including 2 cases of 17q12 deletion, 1 case of 10p15.1p14 deletion and 1 case of 4q21.28q22.1 deletion(including PKD2 gene). There were 8 cases without chromosome abnormality by karyotype analysis. Six clinical WES analysis found NPHS1 gene c.1440+1 G>A and c.925G > T mutations were related to Finnish type congenital nephrotic syndrome in 1 case, PKD1 gene c.6878C>T mutation was related to autosomal dominant polycystic kidney disease (ADPKD) in 1 case, and there was no definitive mutation in 4 cases. Conclusions:CMA and next generation sequencing are powerful tools for accurate diagnosis, treatment and genetic counseling of fetal congenital renal cystic diseases. For congenital cystic nephropathy, genetic detection is helpful to clarify the etiology, and provide more exactly informations for prognosis evaluation, treatment and family genetic counseling.

Identification of SPAST gene variant in a pedigree affected with hereditary spastic paraplegia type 4 / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a pedigree affected with hereditary spastic paraplegia type 4 (HSP4).@*METHODS@#Peripheral venous blood samples were taken from members of the four-generation pedigree and 50 healthy controls for the extraction of genomic DNA. Genes associated with peripheral neuropathy and hereditary spastic paraplegia were captured and subjected to targeted capture and next-generation sequencing. The results were confirmed by Sanger sequencing.@*RESULTS@#DNA sequencing suggested that the proband has carried a heterozygous c.1196C>G variant in exon 9 of the SPAST gene, which can cause substitution of serine by threonine at position 399 (p.Ser399Trp) and lead to change in the protein function. The same variant was also detected in other patients from the pedigree but not among unaffected individuals or the 50 healthy controls. Based on the ACMG 2015 guidelines, the variant was predicted to be possibly pathogenic.@*CONCLUSION@#The c.1196C>G variant of the SPAST gene probably underlay the HSP4 in this pedigree.

Practice of standardized training of clinical medical genetics / 中华医学教育探索杂志

In 2014, the training of clinical medical genetics was included in the training sequence of resident standardized training in China. The standardized training of clinical geneticist in China started relatively late. As a whole, the training and qualification system of clinical hereditary physicians are still in the process of development and perfection. Based on "Rules for the training of department of medical genetics", basic medical genetics resident training system was established in Henan Provincial People's Hospital. Additionally, we took advantage of interactive online education platform, multiple disciplinary team, the analysis of positive case report, literature report and other teaching practices combined with the tutor system. After 4 years of exploration and practice, the program can quickly improve the residents' comprehensive ability, such as theoretical knowledge, professional literacy, clinical practice skills, and scientific research ability.

Prenatal diagnosis of a fetus affected with Finnish type congenital nephrotic syndrome / 中华医学遗传学杂志

Objective@#To explore the genetic basis for a fetus suspected for congenital nephrotic syndrome of Finland (CNF).@*Methods@#Genomic DNA was extracted from peripheral and umbilical cord blood samples derived from both parents and the fetus. Potential variants were detected by using next-generation sequencing. Suspected variants were confirmed by Sanger sequencing.@*Results@#The fetus was found to carry compound heterozygous variants c. 1440+ 1G>A and c. 925G>T of the NPHS1 gene, which were respectively inherited from its mother and father.@*Conclusion@#Identification of the compound heterozygous NPHS1 variants has enabled diagnosis of CNF in the fetus and genetic counseling for the affected family.

Genetic diagnosis of a child with Smith-Magenis syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the molecular mechanism of a girl with developmental delay and intellectual disability.@*METHODS@#Chromosomal karotypes of the child and her parents were analyzed with routine G-banding method. Their genomic DNA was also analyzed with array comparative genomic hybridization (aCGH) for chromosomal duplications/deletions.@*RESULTS@#No karyotypic abnormality was detected in the child and her parents, while aCGH has identified a de novo 3.37 Mb deletion at 17p11.2 in the child.@*CONCLUSION@#The child was diagnosed with Smith-Magenis syndrome, for which RAI1 may be the causative gene.

Prenatal diagnosis of a fetus affected with Finnish type congenital nephrotic syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a fetus suspected for congenital nephrotic syndrome of Finland (CNF).@*METHODS@#Genomic DNA was extracted from peripheral and umbilical cord blood samples derived from both parents and the fetus. Potential variants were detected by using next-generation sequencing. Suspected variants were confirmed by Sanger sequencing.@*RESULTS@#The fetus was found to carry compound heterozygous variants c.1440+1G>A and c.925G>T of the NPHS1 gene, which were respectively inherited from its mother and father.@*CONCLUSION@#Identification of the compound heterozygous NPHS1 variants has enabled diagnosis of CNF in the fetus and genetic counseling for the affected family.

Recurrent Angelman syndrome caused by a rare partial deletion of UBE3A gene / 中华医学遗传学杂志

OBJECTIVE@#To provide genetic testing for two brothers with mental retardation and epilepsy.@*METHODS@#Array comparative genomic hybridization (aCGH) was used to detect copy number variations in the two patients, their parents and maternal grandparents. Methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) was utilized to delineate the deleted region in the pedigree.@*RESULTS@#A 138 kb deletion in 15q11.2 region was detected by aCGH in both patients, which encompassed part of the UBE3A gene. MS-MLPA has narrowed down the region to exons 8 to 14 of the UBE3A gene. The same deletion was also found in their mother and grandfather.@*CONCLUSION@#The pathogenesis of this rare form of recurrent Angelman syndrome may be attributed to the partial deletion of maternal UBE3A gene.

Study on application of next-generation sequencing technology in diagnosis of cardio-facio-cutaneous syndrome / 重庆医学

Objective To explore the role of next-generation sequencing(NGS)technology in the assisted diagnosis of RA-Sopathies.Methods Peripheral blood was extracted from 1 child patient with suspected Noonan syndrome and her parents,and the gene mutations were detected by adopting the aCGH and NGS.The results were verified by Sanger sequencing.Results The NGS results revealed that the heterozygous mutation of c.1406G>A existed in BRAF gene,and the results of Sanger sequencing in this child case was consistent with the NGS results.The Sanger sequencing results in her parents showed the locus was G/G wild type. Conclusion This child case was diagnosed as CFC.NGS plays a good auxiliary role in the differentiation diagnosis of RASopathies.

Identification of a novel EXT1 mutation in a pedigree affected with hereditary multiple exostosis / 中华医学遗传学杂志

OBJECTIVE To detect potential mutations of the EXT1 and EXT2 genes in a pedigree affected with hereditary multiple exostosis (HME). METHODS For a four-generation family with 7 affected individuals from 17 family members,genomic DNA was extracted from peripheral venous blood samples. All exons of the EXT1 and EXT2 genes were screened for potential mutation by PCR and Sanger sequencing. RESULTS A novel heterozygous frameshift mutation c.1202delT (p.I401Tfs*2)was found in exon 4 of the EXT1 gene in the proband and the other 6 affected individuals. The same mutation was not detected among the healthy members from the family. The mutation has given rise a truncated EXT1 protein with loss of 345 amino acids. CONCLUSION A novel frameshift mutation of the EXT1 gene has been identified in a pedigree affected with HME, which has enriched the mutational spectrum of the EXT1 gene and may facilitate genetic counseling and prenatal diagnosis for the family.

Prenatal diagnosis and genetic analysis of a fetus with endocardial cushion defects / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To perform prenatal diagnosis for a fetus with endocardial cushion defect and explore its mechanism.</p><p><b>METHODS</b>The karotypes of the fetus and its parents were analyzed by routine G-banding. Their genomic DNA was also analyzed by array comparative genomic hybridization (aCGH).</p><p><b>RESULTS</b>The fetus and its mother were found to have a karyotype of 46, XX, inv(8)(p21q24.1), while no karyotypic abnormality was detected for the father. aCGH has detected a 15.14 Mb deletion at 8p23.3-p22 and a 6.87 Mb duplication at 8q24.23-q24.3 in the fetus.</p><p><b>CONCLUSION</b>The fetus was diagnosed with Rec8 syndrome. Its abnormal chromosomes have derived from the inv(8) carried by its mother. GATA4 and SOX7 may be the key genes for the endocardial cushion defect found in the fetus.</p>

Genetic diagnosis of a child with aortic stenosis and thumb aplasia / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To analyze the molecular mechanism and prognosis of a child with aortic stenosis and thumb aplasia.</p><p><b>METHODS</b>The karotypes of the child and his parents were analyzed with routine G-banding. Their genomic DNA was also analyzed with array comparative genomic hybridization(aCGH) for chromosomal duplications/deletions.</p><p><b>RESULTS</b>No karyotypic abnormality was detected at cytogenetic level for the child and his parents. aCGH identified a de novo 5.86 Mb deletion at 2q22.3-q23.3 in the child.</p><p><b>CONCLUSION</b>The child was diagnosed with 2q23.1 microdeletion syndrome. MBD5 may be the key gene for the 2q23.1 microdeletion syndrome.</p>

Prenatal diagnosis and genetic analysis of a fetus with 2p13.3-p12 microdeletion / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To provide prenatal diagnosis for a pregnant woman with a history of Williams-Beuren syndrome pregnancy.</p><p><b>METHODS</b>The karyotypes of the fetus and his parents were analyzed with routine G-banding. Their genomic DNA was also analyzed with array comparative genomic hybridization (aCGH).</p><p><b>RESULTS</b>No karyotypic abnormality was detected for the fetus and his parents. aCGH has identified a de novo 5.09 Mb deletion at 2p13.3-p12 in the fetus.</p><p><b>CONCLUSION</b>The 2p13.3-p12 microdeletion carried by the fetus was de novo. As it has involved dosage-sensitive genes SPR and DCTN1, the deletion is probably pathogenic.</p>

Analysis of WAS gene mutation in a Chinese family affected with Wiskott-Aldrich syndrome / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To detect potential mutation of the WAS gene in a Chinese family affected with Wiskott-Aldrich syndrome.</p><p><b>METHODS</b>Peripheral blood samples were collected from the proband and his family members. All exons and flanking regions of the WAS gene were subjected to PCR amplification - Sanger sequencing as well as restriction endonuclease analysis. Plasma level of B-cell activating factor (BAFF) was also determined for all family members.</p><p><b>RESULTS</b>A hemizygous mutation (c.257G>A) of the WAS gene was identified in all patients from the family, for which the patient's mother was heterozygous. The same mutation was not found among healthy members of the family. Compared with unaffected members, all patients had a higher level of BAFF.</p><p><b>CONCLUSION</b>The c.257G>A mutation of the WAS gene probably underlies the Wiskott-Aldrich syndrome in this family.</p>

Genetic analysis of a child with cleidocranial dysplasia and 6q21-q22.31 microdeletion / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To carry out genetic analysis on a child with developmental delay and multiple malformation.</p><p><b>METHODS</b>The karotypes of the child and her parents were analyzed with routine chromosomal G-banding. Their genomic DNA was analyzed with array comparative genomic hybridization (aCGH).</p><p><b>RESULTS</b>The karyotype of the proband was determined as 46,XX,del(6)(q22),inv(6)(p21.1q21), while no karyotypic abnormality was detected in her parents. aCGH has identified in the child a de novo 800 kb deletion encompassing the RUNX2 gene at 6p21.1 and a de novo 11.79 Mb deletion at 6q21-q22.31.</p><p><b>CONCLUSION</b>Both of the de novo deletions are pathogenic. Deletion of the RUNX2 gene probably underlies the cleidocranial dysplasia in the patient, while the 6q21-q22.31 deletion may result in malformation of the brain.</p>

Phenotypic and genetic analysis of a boy with partial trisomy of 1q / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To delineate the nature and origin of chromosomal aberration in a boy with mental retardation and multiple congenital deformities.</p><p><b>METHODS</b>The karotypes of the proband and his parents were analyzed with routine G-banded chromosomal analysis. Genomic DNA was also analyzed with array comparative genomic hybridization (aCGH) assay.</p><p><b>RESULTS</b>The karyotype of the proband was 46,XY,add(1)(p36.3). No karyotypic abnormality was detected in either parent. aCGH has identified a de novo 25.1 Mb duplication at 1q42q44 in the proband.</p><p><b>CONCLUSION</b>The de novo 1q42q44 duplication, which may be due to non-allelic homologous recombination mediated by low copy repeats, probably underlies the abnormalities in the proband.</p>