RESUMO
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.
Assuntos
Cardiomiopatia Dilatada , Distrofia Muscular de Duchenne , Humanos , Qualidade de Vida , Consenso , Distrofina/genética , Distrofia Muscular de Duchenne/diagnóstico , Distrofia Muscular de Duchenne/genética , Distrofia Muscular de Duchenne/terapia , Cardiomiopatia Dilatada/genética , EletrocardiografiaRESUMO
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.
Assuntos
Deficiência Intelectual , Miopia , Feminino , Humanos , População do Leste Asiático , Deficiência Intelectual/genética , Mutação , Miopia/genética , Linhagem , Proteínas de Transporte Vesicular/genética , Pré-Escolar , CriançaRESUMO
Prospective research have shown that whole exome sequencing (WES) may be considered when a diagnosis cannot be obtained using routine prenatal methods, e.g., chromosomal karyotyping and copy number variation sequencing, for fetuses with significant structural anomalies. WES can increase the diagnostic rate of genetic disorders in such fetuses by 8% - 10%. Prenatal WES has been gaining wide acceptance. However, due to the limitations of fetal phenotypic evaluation and complexity of ethical issues in prenatal diagnosis, to justify and standardize the application of prenatal WES and maximize its clinical utility has become an urgent need. In view of this, a consensus has been formed by referring to the latest guidelines, expert consensus and authoritative literature. This consensus has put forward suggestions on the suitable objects of prenatal WES, pre-test consultation, sampling and laboratory testing, results report, post-test consultation, pregnancy outcome follow-up, multidisciplinary consultation of difficult cases, preservation of prenatal WES samples and data information.
Assuntos
Variações do Número de Cópias de DNA , Exoma , Consenso , Feminino , Feto/anormalidades , Humanos , Gravidez , Primeiro Trimestre da Gravidez , Diagnóstico Pré-Natal , Estudos Prospectivos , Ultrassonografia Pré-Natal , Sequenciamento do Exoma/métodosRESUMO
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.
Assuntos
Contratura , Moléculas de Adesão Celular Neuronais , China , Contratura/genética , Feminino , Humanos , Recém-Nascido , Mutação , Linhagem , Gravidez , Sequenciamento do ExomaRESUMO
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.
Assuntos
Adenosina Desaminase , Proteínas de Ligação a RNA , Adenosina Desaminase/genética , China , Feminino , Humanos , Mutação , Linhagem , Transtornos da Pigmentação/congênito , Proteínas de Ligação a RNA/genéticaRESUMO
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.
Assuntos
Paraplegia/genética , Paraplegia Espástica Hereditária/genética , Espastina/genética , Sequência de Bases , Humanos , Mutação , Linhagem , Análise de Sequência de DNARESUMO
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.
Assuntos
Síndrome de Smith-Magenis/genética , Criança , Deleção Cromossômica , Duplicação Cromossômica , Cromossomos Humanos Par 17/genética , Hibridização Genômica Comparativa , Feminino , Humanos , CariotipagemRESUMO
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.
Assuntos
Síndrome de Angelman , Hibridização Genômica Comparativa , Variações do Número de Cópias de DNA , Feminino , Deleção de Genes , Humanos , Masculino , Deleção de Sequência , Ubiquitina-Proteína LigasesRESUMO
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.
Assuntos
Síndrome Nefrótica/congênito , Síndrome Nefrótica/diagnóstico , Feminino , Feto , Finlândia , Heterozigoto , Humanos , Proteínas de Membrana/genética , Gravidez , Diagnóstico Pré-NatalRESUMO
OBJECTIVE: To detect potential mutation of the WAS gene in a Chinese family affected with Wiskott-Aldrich syndrome. METHODS: 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. RESULTS: 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. CONCLUSION: The c.257G>A mutation of the WAS gene probably underlies the Wiskott-Aldrich syndrome in this family.
Assuntos
Mutação , Proteína da Síndrome de Wiskott-Aldrich/genética , Síndrome de Wiskott-Aldrich/genética , Fator Ativador de Células B/sangue , Pré-Escolar , Heterozigoto , Humanos , MasculinoRESUMO
OBJECTIVE: To provide prenatal diagnosis for a pregnant woman with a history of Williams-Beuren syndrome pregnancy. METHODS: 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). RESULTS: 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. CONCLUSION: 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.
Assuntos
Deleção Cromossômica , Transtornos Cromossômicos/embriologia , Transtornos Cromossômicos/genética , Cromossomos Humanos Par 2/genética , Doenças Fetais/genética , Adulto , Transtornos Cromossômicos/diagnóstico , Feminino , Doenças Fetais/diagnóstico , Testes Genéticos , Humanos , Cariótipo , Diagnóstico Pré-NatalRESUMO
OBJECTIVE: To analyze the molecular mechanism and prognosis of a child with aortic stenosis and thumb aplasia. METHODS: 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. RESULTS: 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. CONCLUSION: The child was diagnosed with 2q23.1 microdeletion syndrome. MBD5 may be the key gene for the 2q23.1 microdeletion syndrome.
Assuntos
Estenose da Valva Aórtica/genética , Transtornos Cromossômicos/genética , Cromossomos Humanos Par 2/genética , Polegar/anormalidades , Criança , Bandeamento Cromossômico , Deleção Cromossômica , Transtornos Cromossômicos/diagnóstico , Hibridização Genômica Comparativa , Proteínas de Ligação a DNA/genética , Humanos , MasculinoRESUMO
OBJECTIVE: To perform prenatal diagnosis for a fetus with endocardial cushion defect and explore its mechanism. METHODS: 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). RESULTS: 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. CONCLUSION: 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.
Assuntos
Comunicação Atrioventricular/embriologia , Comunicação Atrioventricular/genética , Doenças Fetais/genética , Adulto , Aberrações Cromossômicas , Bandeamento Cromossômico , Comunicação Atrioventricular/diagnóstico , Feminino , Doenças Fetais/diagnóstico , Testes Genéticos , Humanos , Cariotipagem , Gravidez , Diagnóstico Pré-NatalRESUMO
OBJECTIVE: To carry out genetic analysis on a child with developmental delay and multiple malformation. METHODS: 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). RESULTS: 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. CONCLUSION: 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.
Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 6 , Displasia Cleidocraniana/genética , Subunidade alfa 1 de Fator de Ligação ao Core/genética , Testes Genéticos , Pré-Escolar , Bandeamento Cromossômico , Hibridização Genômica Comparativa , Feminino , Humanos , CariotipagemRESUMO
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.
Assuntos
Éxons/genética , Exostose Múltipla Hereditária/genética , Mutação da Fase de Leitura , N-Acetilglucosaminiltransferases/genética , Adulto , Sequência de Aminoácidos , Sequência de Bases , Análise Mutacional de DNA , Feminino , Heterozigoto , Humanos , Masculino , Linhagem , Homologia de Sequência de AminoácidosRESUMO
OBJECTIVE: To determine the origin of chromosomal aberration in a boy with mental retardation and multiple congenital malformations. METHODS: The karotypes of the proband and his parents were analyzed with conventional G-banding. Their genomic DNA was analyzed with array comparative genomic hybridization (aCGH). RESULTS: No karyotypic abnormality was detected in the proband and his parents. aCGH has identified a de novo 405 kb deletion at 9q34.3 in the proband, which encompassed the EHMT1 gene and part of CACNA1B gene. CONCLUSION: The de novo 9q34.3 deletion probably underlies the mental retardation and development delay in the boy. EHMT1 may be one of the key genes responsible for 9q34.3 microdeletion syndrome.
Assuntos
Anormalidades Craniofaciais/genética , Cardiopatias Congênitas/genética , Deficiência Intelectual/genética , Criança , Bandeamento Cromossômico , Deleção Cromossômica , Cromossomos Humanos Par 9/genética , Hibridização Genômica Comparativa , Histona-Lisina N-Metiltransferase/genética , Humanos , Cariotipagem , MasculinoRESUMO
OBJECTIVE: To delineate the nature and origin of chromosomal aberration in a boy with mental retardation and multiple congenital deformities. METHODS: 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. RESULTS: 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. CONCLUSION: 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.
Assuntos
Cromossomos Humanos Par 1/genética , Trissomia , Pré-Escolar , Bandeamento Cromossômico , Testes Genéticos , Humanos , Cariotipagem , Masculino , FenótipoRESUMO
OBJECTIVE: To determine the origin and pathogenicity of a chromosomal aberration for a fetus and analyze the possible mechanism. METHODS: The karotypes of the fetus and its parents were analyzed with routine G-banding. Their genomic DNA was also analyzed with array comparative genomic hybridization (aCGH). RESULTS: No karyotypic abnormality was detected at cytogenetic level for the fetus and its parents. aCGH has identified a de novo 2.04 Mb deletion at 6q27 in the fetus. The region involves candidate genes responsible for structural brain abnormalities. The area flanking the chromosomal breakpoint contains a 2410 bp sequence rich in palindromes which can form stable secondary structures. CONCLUSION: The de novo 6q27 deletion is pathogenic. The 6q27 deletion may be responsible for the structural brain abnormalities in the fetus. The palindrome sequence flanking the chromosomal breakpoint may be involved the formation of the 6q27 deletion.
Assuntos
Deleção Cromossômica , Cromossomos Humanos Par 6 , Diagnóstico Pré-Natal , Adulto , Hibridização Genômica Comparativa , Feminino , Testes Genéticos , Humanos , GravidezRESUMO
OBJECTIVE: To conduct genetic diagnosis for a family affected with hamophilia A. METHODS: Potential mutations of the F8 gene were analyzed with PCR and Sanger sequencing. Carriers of the mutation were identified through linkage analysis using short tandem repeat (STR) markers. Suspected mutations were verified among 100 healthy controls to rule out genetic polymorphism. Prenatal diagnosis was provided based on the above results. RESULTS: Sequencing analysis has identified two mutations, c.1 A>T and c.4 C>T, which have replaced the start codon (ATG) with leucine (TTG) and glutamine (GAA) with the stop codon (TAA), respectively. The same mutations were not found among the 100 healthy controls. The patient's mother and sister were heterozygous for the same mutations. Upon prenatal diagnosis, the fetus was determined as a male and did not harbor the above mutations. Linkage analysis also confirmed that the fetus has inherited the non-risk X chromosome from his maternal grandfather. CONCLUSION: Detection of pathogenic mutations can enable prenatal diagnosis for the disease.
Assuntos
Fator VIII/genética , Hemofilia A/genética , Mutação/genética , Adulto , Feminino , Ligação Genética/genética , Humanos , Masculino , Diagnóstico Pré-Natal/métodos , Adulto JovemRESUMO
BACKGROUNDS: Down syndrome (DS), caused by triplication of human chromosome 21, is the most common aneuploidies. The main characteristic of DS patients is intellectual disability. MicroRNAs (miRNAs) play important regulatory roles in various biological processes, such as embryonic development, cell differentiation, proliferation and apoptosis. Several miRNAs have shown association with DS. However, the role of miRNAs in DS patients has not been well elaborated. METHODS: In this research, total RNA extracted from fetal hippocampal tissues was used to analyze miRNA and mRNA expression via Affymetrix miRNA 4.0 and PrimeView Human Gene Expression Array, respectively. Then miRNA and gene expression profiles were integrated by correlation analysis to identify dysregulated miRNAs with their predicted target mRNAs. Microarray data were further validated by real-time PCR. Regulation of zeste homolog 2 (EZH2) expression by hsa-miR-138 was determined by luciferase reporter assay. RESULTS: We analyzed microRNA expression profile in hippocampal tissues from DS fetal using miRNA microarray. Further with the use of mRNA microarray data, we integrate miRNA expression and mRNA expression in hippocampus of trisomy 21 fetus to elucidate the mechanism that underlying DS abnormalities. We characterized the repertoire of specific miRNAs involved in hippocampus in trisomy 21 patients, highlighting hsa-miR-138 and hsa-miR-409, in particular the importance of hsa-miR-138, especially the -5p strand. Furthermore, the expression level of predicted target genes of hsa-miR-138-5p in trisomy 21 fetus, including zeste homolog 2 (EZH2) were further confirmed. In addition, luciferase assay indicated that EZH2 was a direct target of hsa-miR-138 in HEK293T cells. CONCLUSION: The function of hsa-miR-138-5p and its target EZH2 was involved in hippocampus in DS patients. Our findings provide a clue to study the underlying molecular mechanisms in DS patients, and its potential contribution in improving understanding of intellectual disability development in DS patients.