Catalogue Search | MBRL
Search Results Heading
Explore the vast range of titles available.
MBRLSearchResults
-
DisciplineDiscipline
-
Is Peer ReviewedIs Peer Reviewed
-
Item TypeItem Type
-
SubjectSubject
-
YearFrom:-To:
-
More FiltersMore FiltersSourceLanguage
Done
Filters
Reset
27
result(s) for
"Au, Kit Sing"
Sort by:
The genomic landscape of tuberous sclerosis complex
by
Martin, Katie R.
,
Dittenhafer-Reed, Kristin E.
,
Krueger, Darcy A.
in
38/91
,
45/23
,
631/208/69
2017
Tuberous sclerosis complex (TSC) is a rare genetic disease causing multisystem growth of benign tumours and other hamartomatous lesions, which leads to diverse and debilitating clinical symptoms. Patients are born with
TSC1
or
TSC2
mutations, and somatic inactivation of wild-type alleles drives MTOR activation; however, second hits to
TSC1/TSC2
are not always observed. Here, we present the genomic landscape of TSC hamartomas. We determine that TSC lesions contain a low somatic mutational burden relative to carcinomas, a subset feature large-scale chromosomal aberrations, and highly conserved molecular signatures for each type exist. Analysis of the molecular signatures coupled with computational approaches reveals unique aspects of cellular heterogeneity and cell origin. Using immune data sets, we identify significant neuroinflammation in TSC-associated brain tumours. Taken together, this molecular catalogue of TSC serves as a resource into the origin of these hamartomas and provides a framework that unifies genomic and transcriptomic dimensions for complex tumours.
Tuberous sclerosis complex (TSC) is a rare genetic disease causing multisystem tumour growth. Here the authors analyse 111 TSC-associated tissues for TSC1/TSC2 status, DNA mutations, copy number aberrations, differential gene expression and DNA methylation patterns providing a comprehensive genomic landscape.
Journal Article
ARMC5 controls the degradation of most Pol II subunits, and ARMC5 mutation increases neural tube defect risks in mice and humans
by
Shi, Wei
,
Gauthier, Marie-Soleil
,
Gagliardi, Lucia
in
Adrenal glands
,
Animal Genetics and Genomics
,
Animals
2024
Background
Neural tube defects (NTDs) are caused by genetic and environmental factors. ARMC5 is part of a novel ubiquitin ligase specific for POLR2A, the largest subunit of RNA polymerase II (Pol II).
Results
We find that ARMC5 knockout mice have increased incidence of NTDs, such as spina bifida and exencephaly. Surprisingly, the absence of ARMC5 causes the accumulation of not only POLR2A but also most of the other 11 Pol II subunits, indicating that the degradation of the whole Pol II complex is compromised. The enlarged Pol II pool does not lead to generalized Pol II stalling or a generalized decrease in mRNA transcription. In neural progenitor cells, ARMC5 knockout only dysregulates 106 genes, some of which are known to be involved in neural tube development. FOLH1, critical in folate uptake and hence neural tube development, is downregulated in the knockout intestine. We also identify nine deleterious mutations in the ARMC5 gene in 511 patients with myelomeningocele, a severe form of spina bifida. These mutations impair the interaction between ARMC5 and Pol II and reduce Pol II ubiquitination.
Conclusions
Mutations in ARMC5 increase the risk of NTDs in mice and humans. ARMC5 is part of an E3 controlling the degradation of all 12 subunits of Pol II under physiological conditions. The Pol II pool size might have effects on NTD pathogenesis, and some of the effects might be via the downregulation of FOLH1. Additional mechanistic work is needed to establish the causal effect of the findings on NTD pathogenesis.
Journal Article
Burden of rare deleterious variants in WNT signaling genes among 511 myelomeningocele patients
by
Ashley-Koch, Allison
,
Au, Kit Sing
,
Hixson, James E.
in
Binding sites
,
Biology and Life Sciences
,
Cell Polarity
2020
Genes in the noncanonical WNT signaling pathway controlling planar cell polarity have been linked to the neural tube defect myelomeningocele. We hypothesized that some genes in the WNT signaling network have a higher mutational burden in myelomeningocele subjects than in reference subjects in gnomAD. Exome sequencing data from 511 myelomeningocele subjects was obtained in-house and data from 29,940 ethnically matched subjects was provided by version 2 of the publicly available Genome Aggregation Database. To compare mutational burden, we collapsed rare deleterious variants across each of 523 human WNT signaling genes in case and reference populations. Ten WNT signaling genes were disrupted with a higher mutational burden among Mexican American myelomeningocele subjects compared to reference subjects (Fishers exact test, P ≤ 0.05) and seven different genes were disrupted among individuals of European ancestry compared to reference subjects. Gene ontology enrichment analyses indicate that genes disrupted only in the Mexican American population play a role in planar cell polarity whereas genes identified in both populations are important for the regulation of canonical WNT signaling. In summary, evidence for WNT signaling genes that may contribute to myelomeningocele in humans is presented and discussed.
Journal Article
Identification of 54 large deletions/duplications in TSC1 and TSC2 using MLPA, and genotype-phenotype correlations
by
Franz, David
,
Lazarus, Ross
,
Au, Kit Sing
in
Analysis
,
Biological and medical sciences
,
Cell physiology
2007
Tuberous sclerosis (TSC) is an autosomal dominant disorder caused by mutations in either of two genes, TSC1 and TSC2. Point mutations and small indels account for most TSC1 and TSC2 mutations. We examined 261 TSC DNA samples (209 small-mutation-negative and 52 unscreened) for large deletion/duplication mutations using multiplex ligation-dependent probe amplification (MLPA) probe sets designed to permit interrogation of all TSC1/2 exons, as well as 15-50 kb of flanking sequence. Large deletion/duplication mutations in TSC1 and TSC2 were identified in 54 patients, of which 50 were in TSC2, and 4 were in TSC1. All but two mutations were deletions. Only 13 deletions were intragenic in TSC2, and one in TSC1, so that 39 (73%) deletions extended beyond the 5', 3' or both ends of TSC1 or TSC2. Mutations were identified in 24% of small-mutation-negative and 8% of unscreened samples. Eight of 54 (15%) mutations were mosaic, affecting 34-62% of cells. All intragenic mutations were confirmed by LR-PCR. Genotype/phenotype analysis showed that all (21 of 21) patients with TSC2 deletions extending 3' into the PKD1 gene had kidney cysts. Breakpoints of intragenic deletions were randomly distributed along the TSC2 sequence, and did not preferentially involve repeat sequence elements. Our own 20-plex probe sets gave more robust performance than the 40-plex probe sets from MRC-Holland. We conclude that large deletions in TSC1 and TSC2 account for about 0.5 and 6% of mutations seen in TSC patients, respectively, and MLPA is a highly sensitive and accurate detection method, including for mosaicism.
Journal Article
Association between training experience and readiness for advance care planning among healthcare professionals: a cross-sectional study
by
Yuen, Kwok-keung
,
Kwok, Annie Oi-ling
,
Yuen, Jacqueline Kwan-yuk
in
Advance Care Planning
,
Advance directives
,
Aging (Individuals)
2020
Background
Training has been found effective in improving healthcare professionals’ knowledge, confidence, and skills in conducting advance care planning (ACP). However, the association between training and its actual practice in the clinical setting has not been well demonstrated. To fill this gap, this paper examines the association between their readiness for ACP, in terms of perceived relevancy of ACP with their clinical work, attitudes toward and confidence and willingness to perform it, based on the Theory Planned Behavior and relevant training experiences.
Methods
An online survey about experiences about ACP of healthcare professionals, including physicians, nurses, social workers, and allied healthcare professionals, currently working in hospital and community care in Hong Kong was conducted.
Results
Of 250 respondents, approximately half (52.0%) had received ACP-related training. Those with relevant training reported significantly more positive in the perceived clinical relevance, willingness, and confidence in conducting ACP and different levels of agreement with 19 out of the 25 statements in a questionnaire about attitudes toward ACP than those without (
p
s ≤ 0.001–0.05). Respondents who received training only in a didactic format reported a significantly lower level of confidence in conducting ACP than did others who received a blended mode of learning (
p
= 0.012). Notwithstanding significant differences between respondents with and without relevant training, respondents generally acknowledged their roles in initiating conversations and appreciated ACP in preventing decisional conflict in surrogate decision-making regardless of their training experience.
Conclusions
This paper revealed the association between training and higher level of readiness toward ACP among healthcare professionals. The findings showed that training is a predictor of their readiness for ACP in terms of perceived relevancy, willingness, and confidence. Those who had received training were less likely to consider commonly reported barriers such as time constraints, cultural taboos, and avoidance among patients and family members as hindrances to ACP implementation.
Journal Article
Identification of novel candidate risk genes for myelomeningocele within the glucose homeostasis/oxidative stress and folate/one‐carbon metabolism networks
2020
Background Neural tube defects (NTDs) are the second most common complex birth defect, yet, our understanding of the genetic contribution to their development remains incomplete. Two environmental factors associated with NTDs are Folate and One Carbon Metabolism (FOCM) and Glucose Homeostasis and Oxidative Stress (GHOS). Utilizing next‐generation sequencing of a large patient cohort, we identify novel candidate genes in these two networks to provide insights into NTD mechanisms. Methods Exome sequencing (ES) was performed in 511 patients, born with myelomeningocele, divided between European American and Mexican American ethnicities. Healthy control data from the Genome Aggregation database were ethnically matched and used as controls. Rare, high fidelity, nonsynonymous predicted damaging missense, nonsense, or canonical splice site variants in independently generated candidate gene lists for FOCM and GHOS were identified. We used a gene‐based collapsing approach to quantify mutational burden in case and controls, with the control cohort estimated using cumulative allele frequencies assuming Hardy–Weinberg equilibrium. Results We identified 45 of 837 genes in the FOCM network and 22 of 568 genes in the GHOS network as possible NTD risk genes with p < 0.05. No nominally significant risk genes were shared between ethnicities. Using a novel approach to mutational burden we identify 55 novel NTD risk associations. Conclusions We provide a means of utilizing large publicly available sequencing datasets as controls for sequencing projects examining rare disease. This approach confirmed existing risk genes for myelomeningocele and identified possible novel risk genes. Lastly, it suggests possible distinct genetic etiologies for this malformation between different ethnicities. Neural tube defects (NTDs) are the second most common complex congenital birth defect and their genetic etiology remains incompletely understood. We utilize exome sequencing of 511 individuals with myelomeningocele and public database controls to identify candidate risk genes through mutational burden analysis. We present 64 candidate risk genes for NTDs, 56 of which are novel associations, and provide evidence of possible distinct molecular pathway roles for NTD risk in different ethnicities.
Journal Article
Folate Metabolism Gene 5,10-Methylenetetrahydrofolate Reductase (MTHFR) Is Associated with ADHD in Myelomeningocele Patients
by
Au, Kit Sing
,
Dennis, Maureen
,
Northrup, Hope
in
5, 10-Methylenetetrahydrofolate reductase (FADH2)
,
Amino acids
,
Attention Deficit Disorder with Hyperactivity - complications
2012
The objective of this study was to examine the relation between the 5, 10-methylenetetrahydrofolate reductase (MTHFR) gene and behaviors related to attention- deficit/hyperactivity disorder (ADHD) in individuals with myelomeningocele. The rationale for the study was twofold: folate metabolizing genes, (e.g. MTHFR), are important not only in the etiology of neural tube defects but are also critical to cognitive function; and individuals with myelomeningocele have an elevated incidence of ADHD. Here, we tested 478 individuals with myelomeningocele for attention-deficit hyperactivity disorder behavior using the Swanson Nolan Achenbach Pelham-IV ADHD rating scale. Myelomeningocele participants in this group for whom DNAs were available were genotyped for seven single nucleotide polymorphisms (SNPs) in the MTHFR gene. The SNPs were evaluated for an association with manifestation of the ADHD phenotype in children with myelomeningocele. The data show that 28.7% of myelomeningocele participants exhibit rating scale elevations consistent with ADHD; of these 70.1% had scores consistent with the predominantly inattentive subtype. In addition, we also show a positive association between the SNP rs4846049 in the 3'-untranslated region of the MTHFR gene and the attention-deficit hyperactivity disorder phenotype in myelomeningocele participants. These results lend further support to the finding that behavior related to ADHD is more prevalent in patients with myelomeningocele than in the general population. These data also indicate the potential importance of the MTHFR gene in the etiology of the ADHD phenotype.
Journal Article
Mutations and polymorphisms in the tuberous sclerosis complex gene on chromosome 16
by
Rodriguez Jr, Estanislado
,
Rodriguez, Joseph A.
,
Dobyns, William B.
in
Blotting, Southern
,
Chromosomes, Human, Pair 16
,
deletions
1997
Tuberous sclerosis complex (TSC) is an autosomal dominant disorder of benign tumor formation, hamartomata, and hamartias. TSC has been shown to be genetically heterogeneous, with one causative gene mapping to chromosome 9q (denoted TSC1) and at least one other gene on chromosome 16p (denoted TSC2). The TSC2 gene was recently cloned. We have tested 88 TSC probands with the TSC2 cDNA by Southern blotting searching for gross deletions/rearrangements/insertions. We detected two deletions and a rare intragenic polymorphic variant. This is a similar rate of mutation detection (2/88; 2.3%) to that in the orignial report (10/260/;3.8%). The rare polymorphic variant was initially detected in the proband of a chromosome 9‐linked multiplex TSC family. The polymorphism segregated with previously tested markers on chromosome 16 independently of the disease gene, verifying that the variation was unrelated to TSC status. We have also begun searching for subtle mutations by SSCA and direct sequencing. After screening three exons, we found two intragenic polymorphic variants. Both polymorphisms are common, making them useful for linkage studies in known affected families. © 1997 Wiley‐Liss, Inc.
Journal Article
Mutational analysis of the tuberous sclerosis gene TSC2 in patients with pulmonary lymphangioleiomyomatosis
by
Henske, Elizabeth Petri
,
Carsillo, Thomas
,
Northrup, Hope
in
Amino Acid Substitution
,
Base Sequence
,
Biological and medical sciences
2000
Pulmonary lymphangioleiomyomatosis (LAM) is a rare disorder limited almost exclusively to women of reproductive age. LAM affects about 5% of women with tuberous sclerosis complex (TSC). LAM also occurs in women who do not have TSC (sporadic LAM). TSC is a tumour suppressor gene syndrome characterised by seizures, mental retardation, and tumours in the brain, heart, and kidney. Angiomyolipomas, which are benign tumours with smooth muscle, fat, and dysplastic vascular components, are the most common renal tumour in TSC. Renal angiomyolipomas also occur in 63% of sporadic LAM patients. We recently found that 54% of these angiomyolipomas have TSC2 loss of heterozygosity, leading to the hypothesis that sporadic LAM is genetically related to TSC. In this study, we screened DNA from 21 women with sporadic LAM for mutations in all 41 exons of TSC2 . Twelve of the patients had known renal angiomyolipomas. No TSC2 mutations were detected. We did find three silent TSC2 polymorphisms. We conclude that patients with sporadic LAM, including those with renal angiomyolipomas, do not have a high frequency of germline mutations in the coding region of TSC2 .
Journal Article
A novel missense mutation in the GTPase activating protein homology region of TSC2 in two large families with tuberous sclerosis complex
by
Henske, Elizabeth Petri
,
Northrup, Hope
,
Strizheva, Galina D
in
Autism
,
Base Sequence
,
Chromosomes
2001
Tuberous sclerosis complex (TSC) is an autosomal dominant disorder (OMIM 191092) characterised by autism, seizures, mental retardation, benign tumours of the brain, heart, kidney, lung, and skin, and malignant tumours of the kidney. 1 TSC has a wide range of phenotypic variability, with some subjects severely affected and others only mildly affected. [...]we anticipate that these families will be important in the future identification of modifier gene effects in TSC.
Journal Article