Genetic analysis of a female child family with suspected X-linked recessive genetic disease / 中国热带医学

@#Objective　Genetic analysis was performed on a female child with chromosome Xq28 heterozygous deletion and suspected X-linked recessive disease to determine the morbidity and prognosis. Methods　A female child was admitted to the hospital on day 20 because of "jaundice for 20 days and difficulty in stopping bleeding at acupuncture sites". Low depth whole genome test of amniocentesis in late pregnancy suggested missing copy number of hemophilia A and X-linked mental retardation type 72. In order to further confirm the diagnosis and prognosis, peripheral blood of the children and their parents were collected for gene testing, chromosome inactivation test and genetic analysis. Results　Chromosome Xq28 of the child had 439.4 kb copy number heterozygous deletion variation, which was a clear disease-coding gene for functional loss included in ClinGen database. Chromosome inactivation test showed that the paternal X chromosome of the child was extremely inactivated. Haplotype analysis suggested that the normal chromosome of the subject was inherited from the mother, and there was heterozygous deletion on the paternal X chromosome, so it was inferred that the child will not develop disease or just have mild symptoms. Conclusion　It is necessary to analyze the X chromosome inactivation test for female patients with the pathogenic variation of X-linked recessive genetic disease to determine the possibility of the disease.

X-chromosome genetic association test incorporating X-chromosome inactivation and imprinting effects

Studies have shown that many complex diseases are sex-determined. When conducting genetic association studies on Xchromosome, there are two important epigenetic factors which should be considered simultaneously: X-chromosome inactivation and genomic imprinting. Currently, there have been several association tests accounting for the information on X-chromosome inactivation. However, these tests do not take the imprinting effects into account. In this paper, we propose a novel association test simultaneously incorporating X-chromosome inactivation and imprinting effects based on case–parent trios and control–parent trios for female offspring and case–control data for male offspring, denoted by MLRXCII. Extensive simulation studies are carried out to investigate the type I error rate and the test power of the proposed MLRXCII . Simulation results demonstrate that the proposed test controls the type I error rate well andis more powerful than the existing method when imprinting effects exist. The proposed MLRXCII test is valid and powerful in genetic association studies on X-chromosome for qualitative traits and thus is recommended in practice.

XIST Induced by JPX Suppresses Hepatocellular Carcinoma by Sponging miR-155-5p

PURPOSE: The influence of X-inactive specific transcript (XIST) and X-chromosome inactivation associated long non-coding RNAs (lncRNAs) just proximal to XIST (JPX) on hepatocellular carcinoma (HCC) remains controversial in light of previous reports, which the present study aimed to verify. MATERIALS AND METHODS: The DIANA lncRNA-microRNA (miRNA) interaction database was used to explore miRNA interactions with JPX or XIST. JPX, XIST, and miR-155-5p expression levels in paired HCC specimens and adjacent normal tissue were analyzed by RT-qPCR. Interaction between XIST and miR-155-5p was verified by dual luciferase reporter assay. Expression levels of miR-155-5p and its known target genes, SOX6 and PTEN, were verified by RT-qPCR and Western blot in HepG2 cells with or without XIST knock-in. The potential suppressive role of XIST and JPX on HCC was verified by cell functional assays and tumor formation assay using a xenograft model. RESULTS: JPX and XIST expression was significantly decreased in HCC pathologic specimens, compared to adjacent tissue, which correlated with HCC progression and increased miR-155-5p expression. Dual luciferase reporter assay revealed XIST as a direct target of miR-155-5p. XIST knock-in significantly reduced miR-155-5p expression level and increased that of SOX6 and PTEN, while significantly inhibiting HepG2 cell growth in vitro, which was partially reversed by miR-155-5p mimic transfection. JPX knock-in significantly increased XIST expression and inhibited HepG2 cell growth in vitro or tumor formation in vivo in a XIST dependent manner. CONCLUSION: JPX and XIST play a suppressive role in HCC. JPX increases expression levels of XIST in HCC cells, which suppresses HCC development by sponging the cancer promoting miR-155-5p.

Analysis of C43G mutation in the promoter region of the XIST gene in patients with idiopathic primary ovarian insufficiency / 대한생식의학회지

OBJECTIVE: The XIST gene is considered to be an attractive candidate gene for skewed X-chromosome inactivation and a possible cause of primary ovarian insufficiency (POI). The purpose of this study was to investigate whether the XIST gene promoter mutation is associated with idiopathic POI in a sample of the Korean population. METHODS: Subjects consisted of 102 idiopathic POI patients and 113 healthy controls with normal menstrual cycles. Patients with the following known causes of POI were excluded in advance: cytogenetic abnormalities, prior chemo- or radiotherapy, or prior bilateral oophorectomy. Genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism analysis. RESULTS: The mean age of onset of ovarian insufficiency was 28.7+/-8.5 years and the mean values of serum luteinizing and follicle-stimulating hormones and estradiol in the POI group were 31.4+/-18.2 mIU/mL, 74.5+/-41.1 mIU/mL, and 30.5+/-36.7 pg/mL, respectively. We found no cytosine to guanine (C43G) variation in the XIST gene in both POI patients and controls. CONCLUSION: The C43G mutation in the promoter region of the XIST gene was not present in the Korean patients with idiopathic POI in our study, in contrast to our expectation, suggesting that the role of XIST in the pathogenesis of POI is not yet clear.

Clonality analysis of Kaposi's sarcoma lesions by human androgen receptor assay / 中华皮肤科杂志

Objective To analyze the clonality in Kaposi's sarcoma (KS) lesions by evaluating Xchromosome inactivation pattern in the human androgen receptor (HUMARA) gene.Methods Twenty-five paraffinembedded tissue specimens were collected from female patients with KS (n =15) or cutaneous hemangioma (n =10).DNA was extracted from these specimens,and digested with the methylation-sensitive restriction endonuclease Hpa Ⅱ.PCR was performed to amplify the HUMARA gene,and the amplicons were separated on a 10％ denaturing polyacrylamied gel and stained with ethidium bromide (EB).The loss of heterozygosity of the HUMARA gene was defined as the presence of two DNA fragments before and one fragment after the endonuclease digestion.The clonality in KS lesions was assessed based on the above results.Results Among the 15 patients with KS,13 (86.7％) were heterozygous for the HUMARA gene,of which,92.31％ (12/13) showed loss of heterozygosity of the HUMARA gene on X-chromosome,suggesting a monoclonal origin.Of the 10 patients with hemangioma,9 were heterozygous for the HUMARA gene,and only one lost heterozygosity of the HUMARA gene.The heterozygosity rate for HUMARA gene was significantly different between the patients with KS and hemangioma (P ＜ 0.01).No statistical difference was observed in the clonality status of KS between patients of different nationality,at different stages,or between patients with and without complicated human immunodeficiency virus (HIV) infection (all P ＞ 0.05).Conclusion KS is monoclonal in origin.

MICrocephaly, disproportionate pontine and cerebellar hypoplasia syndrome: A clinico-radiologic phenotype linked to calcium/calmodulin-dependent serine protein kinase gene mutation.

MICrocephaly, disproportionate pontine and cerebellar hypoplasia (MICPCH) syndrome, a rare X-linked disorder, generally seen in girls, is characterized by neurodevelopmental delay, microcephaly, and disproportionate pontine and cerebellar hypoplasia. It is caused by inactivating calcium/calmodulin-dependent serine protein kinase (CASK) gene mutations. We report a 2-year-old girl with severe neurodevelopmental delay, microcephaly, minimal pontine hypoplasia, cerebellar hypoplasia, and normal looking corpus callosum, with whom the conventional cytogenetic studies turned out to be normal, and an array-comparative genomic hybridization (a-CGH) analysis showed CASK gene duplication at Xp11.4. Our case highlights the importance of using clinico-radiologic phenotype to guide genetic investigation and it also confirms the role of a-CGH analysis in establishing the genetic diagnosis of MICPCH syndrome, when conventional cytogenetic studies are inconclusive.

Long non-coding RNA: Research progress / 第二军医大学学报

Long non-coding RNA (lncRNA) is a functional RNA segment longer than 200 nucleotides, with little or no protein-coding capacity. LncRNAs can regulate gene expression at epigenetic, transcription and post-transcription level, and widely participate in various physiological and pathological processes. More than one thousand lncRNAs have been found participating in the gene regulation of mammals. However, the functions and mechanism of lncRNA and its relation with disease remain poorly understood. This paper reviews the progress in lncRNA function study and the role of lncRNA in the development and progression of clinical disease.

Evaluación del patrón de inactivación del cromosoma X en portadoras sintomáticas y mujeres con hemofilia / Assessing the inactivation pattern in chromosome X among symptomatic carriers and women with haemophilia

La inactivación del cromosoma X es un fenómeno estocástico que ocurre en la embriogénesis temprana femenina para lograr una compensación de dosis génica respecto a los varones. Ciertos mecanismos genéticos afectan el proceso normal, propiciando una inactivación sesgada con efectos clínicos relevantes en portadoras de trastornos recesivos ligados al cromosoma X, como la hemofilia. La herramienta molecular mayormente utilizada para la evaluación del patrón de inactivación del cromosoma X es la amplificación por PCR del gen del receptor de andrógenos humano (HUMARA). El empleo de esta técnica en portadoras sintomáticas y mujeres con hemofilia permite esclarecer si las manifestaciones de la enfermedad se deben a una lyonización desfavorable. Estos estudios, además, son importantes para la comprensión del proceso de inactivación del cromosoma X en humanos.

X chromosome inactivation is a stochastic event that occurs early in female embryo development to achieve dosage compensation with males. Certain genetic mechanisms affect the normal process causing a skewed X inactivation pattern which has clinical relevance in female carriers of X-linked recessive disorders, like haemophilia. The most commonly used assay to evaluate the X inactivation pattern is the PCR amplification of the human androgen receptor gene (HUMARA). The use of this technique in bleeding carriers and women with haemophilia allows identifying if their hemorrhagic symptoms are due to an unfavourable lyonization. Furthermore, these studies are important for understanding the X chromosome inactivation process in humans.

Relationship between Spondyloppiphyseal Dysplasia Tarda Gene Escaping X Chromosome Inactivation and Spondyloppiphyseal Dysplasia Tarda Phenotype / 实用儿科临床杂志

Objective To explore the relationship between X - linked spondyloepiphyseal dysplasia tarda (SEDL) gene escaping X chromosome inactivation( XCI) and SEDL phenotype. Methods RT - PCR was performed on total RNA which was isolated from blood samples of patients, female carriers and controls. Patients and female carriers were selected from the pedigree with SEDL caused by the mutation (IVS2 - 2A→C) of the gene. cDNA was analyzed by polyacrylamide gelelectrophoresis(PAGE). Results PAGE data indicateed that female carriers expressed both normal and mutant SEDL mRNA,meaning the SEDL gene escaping XCI. Family investigation showed carrier females in the SEDL pedigree presented no symptoms. Conclusions The SEDL gene escaping X chromosome in-activation is firstly identified from human body. This may explain that carrier females present no symptoms.

Mammalian-type dosage compensation mechanism in an insect — Gryllotalpa fossor (Scudder) — Orthoptera.

In Gryllotalpa fossor (Orthoptera) (23, X0 male; 24, XX female) we have established the existence of random X chromosome inactivation for dosage compensation of X-linked genes. Both cytogenetical (DNA replication and transcription) and biochemical (X-linked glucose-6-phosphate dehydrogenase) studies have indicated that one of the two X chromosomes in the female soma (hepatic caeca) is late replicating and transcriptionally silent leaving the other X chromosome to remain active as in males thereby ensuring the production of almost the same amount of X-linked glucose-6-phosphate dehydrogenase in both sexes. Even in oogonia, one of the two X chromosomes continues to retain inactive. Only prior to their entry into meiosis the inactive X chromosome is reactivated. Accordingly, there is two-fold increase m the level of X-linked glucose-6-phosphate dehydrogenase in oocytes, From this it is implied that the restoration of X chromosome inactivation should occur some time during early embryogenesis. Thus, dosage compensation in Gryllotalpa seems to be analogous to that in mammals. Our work bears testimony to the ancient origin of this mechanism.