中华医学遗传学杂志最新文献

Objective: To explore the clinical features and genetic basis for a fetus featuring Rhizomelic skeletal dysplasia.

Methods: A fetus diagnosed at the Reproductive and Genetic Center of Suzhou Municipal Hospital in November 2020 was selected as the study subject. Whole exome sequencing (WES) was carried out for the fetus and its parents. Candidate variants were verified by Sanger sequencing. Peripheral blood smears of both parents were also examined.

Results: The fetus was found to have a small chest and short limbs, which had suggested skeletal dysplasia. Genetic testing revealed that the fetus has harbored compound heterozygous variants of the LBR gene, including a paternally derived c.1687+1G>A and a maternally derived c.1757G>A (p.Arg586His). The blood smear of the father showed Pelger-Huet anomaly with hyposegmentation of neutrophil nuclei, while the neutrophils of the mother appeared to be normal. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP), the c.1757G>A (p.Arg586His) variant was classified as likely pathogenic (PM3_Strong+PM2_Supporting+PP3), and so was the c.1687+1G>A variant (PVS1-Moderate+PM3+PM2-Supporting+PP4).

Conclusion: The compound heterozygous variants of the LBR gene probably underlay the pathogenesis of skeletal dysplasia in this fetus.

Objective: To explore the serological characteristics and genetic variant in a Chinese pedigree with Bw subtype.

Methods: A 32-year-old female proband who had undergone prenatal examination on December 10, 2020 at the 960th Hospital of the PLA Joint Logistics Support Force and five members from her pedigree were selected as the study subjects. Peripheral blood samples were collected and subjected to ABO blood group phenotyping with serological methods and ABO blood group genotyping with fluorescent PCR. Genetic testing and haplotype analysis were carried out by direct sequencing of the entire coding region of the ABO gene in the proband and cloned sequencing of exons 1-7.

Results: The blood type serology of the proband showed Bw, and her ABO blood type genotype determined by fluorescence PCR was B/O. The direct sequencing results showed that the proband had matched the ABO*O.01.01/ABO*B.01 genotype and carried a c.1A>G variant. Cloned sequencing has confirmed the c.1A>G variant to have occurred in the ABO*B.01 allele. Family analysis revealed that the mother of the proband had an O blood type, her husband had a B phenotype, and her three children had a normal B blood type. DNA sequencing showed that the two sons of the proband had a genotype of ABO*B.01 and c.1A>G/ABO*B.01. The daughter of the proband was ABO*O.01.01/ABO*B.01, whilst her mother was ABO*O.01.01/ABO *O.01.02. The novel c.1A>G variant sequence has been registered with the database with a number MZ076785 1.

Conclusion: The novel c.1A>G variant of exon 1 of α- 1,3 galactose aminotransferase gene probably underlay the reduced expression of B antigen in this pedigree.

Objective: To explore the genetic basis for a fetus with nuchal cystic hygroma identified in the first trimester and cholecystomegaly identified in the middle trimester of pregnancy.

Methods: A 27-year-old pregnant woman who had presented at the Antenatal Diagnostic Center of Jinan Maternal and Child Health Care Hospital on October 25, 2018 was selected as the study subject. Chorionic villus sampling was carried out in the first trimester for chromosomal karyotyping and SNP-Array analysis. Amniocentesis was carried out in the second trimester, and peripheral blood of the couple was collected at the same time. Trio whole exome sequencing (WES) was carried out, and candidate variant was verified by Sanger sequencing and bioinformatic analysis.

Results: No abnormality was found by chromosomal karyotyping and SNP-Array, whilst high-throughput sequencing revealed that the fetus had harbored a heterozygous c.7732A>T (p.K2578X) nonsense variant of the NIPBL gene. Following elected abortion, the autopsy results were consistent with features of Cornelia de Lange syndrome (CdLS). The same variant was detected in neither parents and was unreported in the literature. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), it was classified as pathogenic (PVS1+PS2+PM2_Supporting+PP3).

Conclusion: The novel nonsense variant of the NIPBL gene probably underlay the genetic etiology of CdLS in this fetus. Above finding has also enriched the mutational spectrum of the NIPBL gene.

Objective: To explore the clinical features and genetic basis for a child with Intellectual developmental disorder (IDD) and epilepsy.

Methods: A child who was admitted to the Children's Medical Center of the Affiliated Hospital of Guangdong Medical University in February 2021 was selected as the study subject. Clinical data of the child was collected. Peripheral blood samples of the child and her parents were collected and subjected to whole exome sequencing (WES). Candidate variant was verified by Sanger sequencing.

Results: The patient, a 3-month-and-27-day female infant, had developed the symptoms in the neonatal period, which included severe developmental delay, respiratory difficulties and pauses, increased muscle tone of four limbs, feeding difficulty, and seizures. Cerebral MRI revealed bilateral cerebellar hypoplasia, and video EEG showed slightly increased sharp waves emanating predominantly from the right parietal, occipital, and posterior temporal regions. WES revealed that she has harbored a missense c.3196G>A (p.Glu1066Lys) variant of the CLTC gene, which was confirmed to be de novo by Sanger sequencing. Based on the guideline from the American College of Medical Genetics and Genomics (ACMG), the variant was classified as likely pathogenic (PS2+PM2_Supporting+PP3).

Conclusion: The c.3196G>A (p.Glu1066Lys) missense variant of the CLTC gene probably underlay the pathogenesis in this child. Above finding has facilitated her diagnosis and treatment.

α-thalassemia is a type of microcytic hypochromic anemia caused by variants of alpha-globin gene, and is one of the most common monogenic disorders in southern China. The population screening model based on hematologic phenotype has achieved great results in areas with high incidence of thalassemia. However, with the continuous decline of the cost of genetic testing and implementation of screening programs for thalassemia gene carriers, more variants in the alpha-globin gene have been discovered, which also brings great challenges to clinical genetic counseling. From the perspective of alpha-globin genetic analysis, this consensus has discussed the contents of pre- and post-test genetic counseling, with an aim to provide standardized guidance for clinicians.

Char syndrome is a rare autosomal dominant genetic disorder characterized by patent ductus arteriosus, facial dysmorphism, and dysplasia of fingers/toes. It may also be associated with multiple papillae, dental dysplasia, and sleep disorders. TFAP2B has proven to be a pathogenic gene for neural crest derivation and development, and several variants of this gene have been identified. Bone morphogenetic protein signaling plays an important role in embryonic development by participating in limb growth and patterning, and regulation of neural crest cell development. TFAP2B is an upstream regulatory gene for bone morphogenetic proteins 2 and 4. Variants of the TFAP2B gene may lead to abnormal proliferation of neural crest cells by affecting the expression of bone morphogenetic proteins, resulting in multiple organ dysplasia syndrome. In addition, TFAP2B variants may only lead to patent ductus arteriosus instead of typical Char syndrome.

Congenital heart disease (CHD) is one of the most common congenital malformations and a major cause of mortality among neonates and children. Conventional methods for the diagnosis of CHD have relied on clinical features and imaging findings. With the rapid development of genetic techniques, to identify the cause of CHD through genetic diagnosis has gained great significance for the early diagnosis, treatment, and prevention of CHD. However, currently there is still a lack of norms and standards for the genetic diagnosis of CHD. In view of this, experts from the relevant fields have formulated the present norm by integrating the latest research advances on CHD-related genes with the current clinical practice on the diagnosis and treatment of CHD and status quo of genetic diagnosis in China. The norm has been recommended by the Cardiology Section of the Chinese Medical Education Association, the Medical Genetics Branch and the Heart Group of Pediatric Surgery Branch of the Chinese Medical Association, which has formulated the procedures and norms of genetic testing, prenatal diagnosis, and genetic counseling for CHD, with an aim to provide reference for clinicians as the standards for the integrated diagnosis, early treatment, and prevention of CHD.

Structural maintenance of chromosomes (SMC), including cohesin, condensin and the SMC5/6 complex, are protein complexes which maintain the higher structure and dynamic stability of chromatin. Such circular complexes, with similar structures, play pivotal roles in chromatid cohesion, chromosomal condensation, DNA replication and repair, as well as gene transcription. Despite extensive research on the functions of the SMCs, our understanding of the SMC5/6 complex has remained limited compared with the other two complexes. This article has reviewed the architecture and crucial physiological roles of the SMCs, and explored the associated phenotypes resulting from mutations of the SMC components such as Cornelia de Lange syndrome (CdLS) and microcephaly, with an aim to provide insights into their functions in eukaryotic cells and implications for human diseases.

Objective: To explore the genetic basis of a myopathic patient with pathological characteristics including tubular aggregates and vacuoles.

Methods: Next generation sequencing was carried out for the patient, and candidate variant was verified by Sanger sequencing.

Results: Genetic testing revealed that the patient has harbored a heterozygous c.730G>C (p.D244H) variant of Calsequestrin 1 (CASQ1) gene. The same variant was not found in his unaffected parents. Based on guidelines from the American College of Medical Genetics and Genomics, the variant was rated as pathogenic (PS1+PM2+PP3).

Conclusion: The novel c.730G>C (p.D244H) variant of the CASQ1 gene probably underlay the myopathy in this patient. Above finding has enriched the mutational spectrum of the CASQ1 gene.

Objective: To explore the clinical and genetic characteristics of a child with mental retardation, language and motor developmental delay and epilepsy.

Methods: A child who was admitted to the First Affiliated Hospital of Zhengzhou University in March 2020 for intermittent seizures for over two months was selected as the study subject. Clinical data of the child was collected. Peripheral blood samples of the child and his parents were collected and subjected to high throughput sequencing. Candidate variants were verified by Sanger sequencing and bioinformatic analysis.

Results: The clinical manifestations of the child have included mental retardation, language and motor developmental delay, and seizures. High-throughput sequencing revealed that he has harbored a hemizygous splice site variant (NM_032591.3: c.1030-1G>C) of the SLC9A7 gene, which was inherited from his mother and unreported previously.

Conclusion: The hemizygous splice site variant (NM_032591.3: c.1030-1G>C) of the SLC9A7 gene probably underlay the disease in this child. Above finding has provided a basis for clinical diagnosis and genetic counseling.