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ABSTRACT: BACKGROUND: Hirschsprung's (HSCR) disease is characterized by absence of ganglia in the distant bowel. Skin-derived precursor cells (SKPs) are somatic stem cells located in the bulge of hair follicles with high neural plasticity. In this study, we elucidated the therapeutic potential of SKPs for replenishing absent ganglia in HSCR bowel. METHODS: SKPs were isolated from mouse or human skin and cultured in neural differentiation medium to generate various types of neural cells. Expression of stem cell and neural differentiation markers were monitored by reverse-transcription polymerase chain reaction and immunocytochemistry, respectively. Engraftment and differentiation potentials of SKPs were further assessed using ex vivo gut culture with Retk/k aganglionic gut. RESULTS: Expression studies revealed that SKPs express a panel of neural crest markers and three key stemness factors (Klf4, c-Myc and Sox2), which may account for the multipotency of these cells. Subsequent differentiation assays directly demonstrated that both mouse and human SKPs retain high differentiation capacities to form enteric neurons, and glia. Importantly, with ex vivo gut explants assay, we further showed that SKPs colonize and differentiate in the Retk/k aganglionic hindgut explants. CONCLUSION: Our data suggest that SKPs may represent an alternative source of stem cells for the study of cell-based therapy for HSCR.
Journal of Pediatric Surgery 03/2013; 48(3):619-628. · 1.45 Impact Factor
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ABSTRACT: Hirschsprung disease (HSCR, aganglionic megacolon) is a complex genetic disorder of the enteric nervous system (ENS) characterized by the absence of enteric neurons along a variable length of the intestine. While rare variants (RVs) in the coding sequence (CDS) of several genes involved in ENS development lead to disease, the association of common variants (CVs) with HSCR has only been reported for RET (the major HSCR gene) and NRG1. Importantly, RVs in the CDS of these two genes are also associated with the disorder. To assess independent and joint effects between the different types of RET and NRG1 variants identified in HSCR patients, we used 254 Chinese sporadic HSCR patients and 143 ethnically matched controls for whom the RET and/or NRG1 variants genotypes (rare and common) were available. Four genetic risk factors were defined and interaction effects were modeled using conditional logistic regression analyses and pair-wise Kendall correlations. Our analysis revealed a joint effect of RET CVs with RET RVs, NRG1 CVs or NRG1 RVs. To assess whether the genetic interaction translated into functional interaction, mouse neural crest cells (NCCs; enteric neuron precursors) isolated from embryonic guts were treated with NRG1 (ErbB2 ligand) or/and GDNF (Ret ligand) and monitored during the subsequent neural differentiation process. Nrg1 inhibited the Gdnf-induced neuronal differentiation and Gdnf negatively regulated Nrg1-signaling by down-regulating the expression of its receptor, ErbB2. This preliminary data suggest that the balance neurogenesis/gliogenesis is critical for ENS development.
Human Genetics 02/2013; · 5.07 Impact Factor
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ABSTRACT: The availability of human pluriopotent stem cells, embryonic (ESC) and induced pluriopotent (iPSC) stem cells, not only can be a renewable source for investigating the early human development, etiology and progression of different diseases but also recapitulating the disease with the same genomic materials of the patient. In particular, specific neuronal subtypes generated from the patient ESC/iPSCs has become a source for studying disease mechanisms underlying different neurological disorders and allowed drug discovery. In this review, we summarize the recent advances in establishing patient ESC/iPSC to model various neurological diseases. We will also discuss the challenges and limitations of the current disease models and their potential future applications for untangling the unknowns in neurological disorders.
Experimental Cell Research 11/2012; · 3.58 Impact Factor
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Emily H M Wong,
Long Cui,
Chun-Laam Ng,
Clara S M Tang,
Xue-Lai Liu,
Man-Ting So,
Benjamin Hon-Kei Yip,
Guo Cheng,
Ruizhong Zhang,
Wai-Kiu Tang, [......],
Ruoyi Wang,
Tao Chang,
Ivy Hau-Yee Chan,
Patrick Ho-Yu Chung,
Xue-Jun Zhang,
Kenneth Kak-Yuen Wong,
Stacey S Cherny,
Pak-Chung Sham,
Paul Kwong-Hang Tam,
Maria-Mercè Garcia-Barcelo
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ABSTRACT: Anorectal malformations (ARMs, congenital obstruction of the anal opening) are among the most common birth defects requiring surgical treatment (2-5/10,000 live-births) and carry significant chronic morbidity. ARMs present either as isolated or as part of the phenotypic spectrum of some chromosomal abnormalities or monogenic syndromes. The etiology is unknown. To assess the genetic contribution to ARMs, we investigated single nucleotide polymorphisms (SNPs) and copy number variations (CNVs) at genome-wide scale. A total of 363 Han Chinese sporadic ARM-patients and 4,006 Han Chinese controls were included. Overall, we detected a 1.3-fold significant excess of rare-CNVs in patients. Stratification of patients by presence/absence of other congenital anomalies showed that while syndromic-ARM patients carried significantly longer rare duplications than controls (p=0.049), non-syndromic patients were enriched with both rare deletions and duplications when compared to controls (p=0.00031). Twelve chromosomal aberrations and 114 rare-CNVs were observed in patients but not in 868 controls nor 11,943 healthy individuals from the Database of Genomic Variants (DGV). Importantly, these aberrations were observed in isolated-ARM patients. Gene-based analysis revealed 79 genes interfered by CNVs in patients only. In particular, we identified a de novo DKK4 duplication. DKK4 is a member of the WNT signaling pathway which is involved in the development of the anorectal region. In mice, Wnt disruption results in ARMs. Our data suggest a role for rare-CNVs not only in syndromic but also in isolated-ARM patients and provide a list of plausible candidate genes for the disorder.
Human Molecular Genetics 10/2012; · 7.64 Impact Factor
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Clara Sze-Man Tang,
Guo Cheng,
Man-Ting So,
Benjamin Hon-Kei Yip,
Xiao-Ping Miao,
Emily Hoi-Man Wong, Elly Sau-Wai Ngan,
Vincent Chi-Hang Lui,
You-Qiang Song,
Danny Chan, [......],
Patrick Ho-Yu Chung,
Xue-Lai Liu,
Kenneth Kak-Yuen Wong,
Christian R Marshall,
Stephen W Scherer,
Steve Scherer,
Stacey S Cherny,
Pak-Chung Sham,
Paul Kwong-Hang Tam,
Maria-Mercè Garcia-Barceló
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ABSTRACT: Hirschsprung disease (HSCR) is a congenital disorder characterized by aganglionosis of the distal intestine. To assess the contribution of copy number variants (CNVs) to HSCR, we analysed the data generated from our previous genome-wide association study on HSCR patients, whereby we identified NRG1 as a new HSCR susceptibility locus. Analysis of 129 Chinese patients and 331 ethnically matched controls showed that HSCR patients have a greater burden of rare CNVs (p = 1.50 × 10(-5)), particularly for those encompassing genes (p = 5.00 × 10(-6)). Our study identified 246 rare-genic CNVs exclusive to patients. Among those, we detected a NRG3 deletion (p = 1.64 × 10(-3)). Subsequent follow-up (96 additional patients and 220 controls) on NRG3 revealed 9 deletions (combined p = 3.36 × 10(-5)) and 2 de novo duplications among patients and two deletions among controls. Importantly, NRG3 is a paralog of NRG1. Stratification of patients by presence/absence of HSCR-associated syndromes showed that while syndromic-HSCR patients carried significantly longer CNVs than the non-syndromic or controls (p = 1.50 × 10(-5)), non-syndromic patients were enriched in CNV number when compared to controls (p = 4.00 × 10(-6)) or the syndromic counterpart. Our results suggest a role for NRG3 in HSCR etiology and provide insights into the relative contribution of structural variants in both syndromic and non-syndromic HSCR. This would be the first genome-wide catalog of copy number variants identified in HSCR.
PLoS Genetics 05/2012; 8(5):e1002687. · 8.69 Impact Factor
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Clara Sze-Man Tang,
Guo Cheng,
Man-Ting So,
Benjamin Hon-Kei Yip,
Xiao-Ping Miao,
Emily Hoi-Man Wong, Elly Sau-Wai Ngan,
Vincent Chi-Hang Lui,
You-Qiang Song,
Danny Chan, [......],
Liu Lei,
Patrick Ho-Yu Chung,
Xue-Lai Liu,
Kenneth Kak-Yuen Wong,
Christian R Marshall,
Stephen Scherer,
Stacey S Cherny,
Pak-Chung Sham,
Paul Kwong-Hang Tam,
Maria-Mercè Garcia-Barceló
PLoS Genetics 05/2012; 8(5). · 8.69 Impact Factor
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ABSTRACT: Caveolin-1 (Cav1) has been implicated in diverse human cancers, yet its role in hepatocellular carcinoma (HCC) tumourigenesis and metastasis remains elusive. In the current study, we aim to provide a comprehensive understanding regarding the functional role of Cav1 in HCC tumourigenesis and metastasis. Cav1 expression was examined in a panel of human HCC cell lines using western blotting analysis and quantitative RT-PCR and human tissues by immunohistochemistry. Cav1 was not detected in normal liver cell line and all non-tumourous liver tissues but exclusively expressed in HCC cell lines and tissues. Dramatic expression of Cav1 was found in metastatic HCC cell lines and tumours, indicating a progressive increase of Cav1 expression along disease progression. Cav1 overexpression was significantly correlated with venous invasion (p = 0.036). To investigate the functions of Cav1 in HCC, Cav1 overexpressing and knockdown stable clones were established in HCC cells and their tumourigenicity and metastatic potential were examined. Overexpression of Cav1 promoted HCC cell growth, motility, and invasiveness, as well as tumourigenicity in vivo. Conversely, knockdown of Cav1 in metastatic HCC cells inhibited the motility and invasiveness and markedly suppressed the tumour growth and metastatic potential in vivo. Collectively, our findings have shown the exclusive expression of Cav1 in HCC cell lines and clinical samples and revealed an up-regulation of Cav1 along HCC progression. The definitive role of Cav1 in promoting HCC tumourigenesis was demonstrated, and we have shown for the first time in a mouse model that Cav1 promotes HCC metastasis.
The Journal of Pathology 11/2011; 226(4):645-53. · 6.32 Impact Factor
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Elly Sau-Wai Ngan,
Maria-Mercè Garcia-Barceló,
Benjamin Hon-Kei Yip,
Hiu-Ching Poon,
Sin-Ting Lau,
Carmen Ka-Man Kwok,
Eric Sat,
Mai-Har Sham,
Kenneth Kak-Yuen Wong,
Brandon J Wainwright,
Stacey S Cherny,
Chi-Chung Hui,
Pak Chung Sham,
Vincent Chi-Hang Lui,
Paul Kwong-Hang Tam
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ABSTRACT: Hirschsprung (HSCR) disease is a complex genetic disorder attributed to a failure of the enteric neural crest cells (ENCCs) to form ganglia in the hindgut. Hedgehog and Notch are implicated in mediating proliferation and differentiation of ENCCs. Nevertheless, how these signaling molecules may interact to mediate gut colonization by ENCCs and contribute to a primary etiology for HSCR are not known. Here, we report our pathway-based epistasis analysis of data generated by a genome-wide association study on HSCR disease, which indicates that specific genotype constellations of Patched (PTCH1) (which encodes a receptor for Hedgehog) and delta-like 3 (DLL3) (which encodes a receptor for Notch) SNPs confer higher risk to HSCR. Importantly, deletion of Ptch1 in mouse ENCCs induced robust Dll1 expression and activation of the Notch pathway, leading to premature gliogenesis and reduction of ENCC progenitors in mutant bowels. Dll1 integrated Hedgehog and Notch pathways to coordinate neuronal and glial cell differentiation during enteric nervous system development. In addition, Hedgehog-mediated gliogenesis was found to be highly conserved, such that Hedgehog was consistently able to promote gliogenesis of human neural crest-related precursors. Collectively, we defined PTCH1 and DLL3 as HSCR susceptibility genes and suggest that Hedgehog/Notch-induced premature gliogenesis may represent a new disease mechanism for HSCR.
The Journal of clinical investigation 08/2011; 121(9):3467-78. · 15.39 Impact Factor
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Clara Sze-Man Tang, Elly Sau-Wai Ngan,
Wai-Kiu Tang,
Man-Ting So,
Guo Cheng,
Xiao-Ping Miao,
Thomas Yuk-Yu Leon,
Brian Man-Chun Leung,
Kenneth-Jeremy W S Hui,
Vincent Hang-Chai Lui,
Yan Chen,
Ivy Hau-Yee Chan,
Patrick Ho-Yu Chung,
Xue-Lai Liu,
Kenneth Kak-Yuen Wong,
Pak-Chung Sham,
Stacey S Cherny,
Paul Kwong-Hang Tam,
Maria-Mercè Garcia-Barcelo
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ABSTRACT: Hirschsprung disease (HSCR, congenital colon aganglionosis) is a relatively common complex genetic condition caused by abnormal development of the enteric nervous system (ENS). Through a recent genome-wide association study conducted on Chinese HSCR patients, we identified a new HSCR contributing locus, neuregulin 1 (NRG1; 8p12), a gene known to be involved in the development of the ENS. As genes in which disease-associated common variants are found are to be considered as candidates for the search of deleterious rare variants (RVs) in the coding sequences, we sequenced the NRG1 exons of 358 sporadic HSCR patients and 333 controls. We identified a total of 13 different heterozygous RVs including 8 non-synonymous (A28G, E134K, V266L, H347Y, P356L, V486M, A511T, P608A) and 3 synonymous amino acid substitutions (P24P, T169T, L483L), a frameshift (E239fsX10), and a c.503-4insT insertion. Functional analysis of the most conserved non-synonymous substitutions, H347Y and P356L, showed uneven intracellular distribution and aberrant expression of the mutant proteins. Except for T169T and V486M, all variants were exclusive to HSCR patients. Overall, there was a statistically significant over-representation of NRG1 RVs in HSCR patients (p = 0.008). We show here that not only common, but also rare variants of the NRG1 gene contribute to HSCR. This strengthens the role of NRG1.
Human Genetics 06/2011; 131(1):67-76. · 5.07 Impact Factor
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Clara Sze-Man Tang,
Wai-Kiu Tang,
Man-Ting So,
Xiao-Ping Miao,
Brian Man-Chun Leung,
Benjamin Hon-Kei Yip,
Thomas Yuk-Yu Leon, Elly Sau-Wai Ngan,
Vincent Chi-Hang Lui,
Yan Chen,
Ivy Hau-Yee Chan,
Patrick Ho-Yu Chung,
Xue-Lai Liu,
Xuan-Zhao Wu,
Kenneth Kak-Yuen Wong,
Pak-Chung Sham,
Stacey S Cherny,
Paul Kwong-Hang Tam,
Maria-Mercè Garcia-Barceló
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ABSTRACT: The primary pathology of Hirschsprung's disease (HSCR, colon aganglionosis) is the absence of ganglia in variable lengths of the hindgut, resulting in functional obstruction. HSCR is attributed to a failure of migration of the enteric ganglion precursors along the developing gut. RET is a key regulator of the development of the enteric nervous system (ENS) and the major HSCR-causing gene. Yet the reduced penetrance of RET DNA HSCR-associated variants together with the phenotypic variability suggest the involvement of additional genes in the disease. Through a genome-wide association study, we uncovered a ∼350 kb HSCR-associated region encompassing part of the neuregulin-1 gene (NRG1). To identify the causal NRG1 variants contributing to HSCR, we genotyped 243 SNPs variants on 343 ethnic Chinese HSCR patients and 359 controls. Genotype analysis coupled with imputation narrowed down the HSCR-associated region to 21 kb, with four of the most associated SNPs (rs10088313, rs10094655, rs4624987, and rs3884552) mapping to the NRG1 promoter. We investigated whether there was correlation between the genotype at the rs10088313 locus and the amount of NRG1 expressed in human gut tissues (40 patients and 21 controls) and found differences in expression as a function of genotype. We also found significant differences in NRG1 expression levels between diseased and control individuals bearing the same rs10088313 risk genotype. This indicates that the effects of NRG1 common variants are likely to depend on other alleles or epigenetic factors present in the patients and would account for the variability in the genetic predisposition to HSCR.
PLoS ONE 01/2011; 6(1):e16181. · 4.09 Impact Factor
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Man-Ting So,
Thomas Yuk-Yu Leon,
Guo Cheng,
Clara Sze-Man Tang,
Xiao-Ping Miao,
Belinda K Cornes,
Ngoc Ngo Diem,
Long Cui, Elly Sau-Wai Ngan,
Vincent Chai-Hang Lui, [......],
Thanh Liem Nguyen,
Ivy Hau-Yee Chan,
Patrick Ho-Yu Chung,
Xue-Lai Liu,
Ruizhong Zhang,
Kenneth Kak-Yuen Wong,
Pak-Chung Sham,
Stacey S Cherny,
Paul Kwong-Hang Tam,
Maria-Mercè Garcia-Barcelo
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ABSTRACT: Rare (RVs) and common variants of the RET gene contribute to Hirschsprung disease (HSCR; congenital aganglionosis). While RET common variants are strongly associated with the commonest manifestation of the disease (males; short-segment aganglionosis; sporadic), rare coding sequence (CDS) variants are more frequently found in the lesser common and more severe forms of the disease (females; long/total colonic aganglionosis; familial).Here we present the screening for RVs in the RET CDS and intron/exon boundaries of 601 Chinese HSCR patients, the largest number of patients ever reported. We identified 61 different heterozygous RVs (50 novel) distributed among 100 patients (16.64%). Those include 14 silent, 29 missense, 5 nonsense, 4 frame-shifts, and one in-frame amino-acid deletion in the CDS, two splice-site deletions, 4 nucleotide substitutions and a 22-bp deletion in the intron/exon boundaries and 1 single-nucleotide substitution in the 5' untranslated region. Exonic variants were mainly clustered in RET the extracellular domain. RET RVs were more frequent among patients with the most severe phenotype (24% vs. 15% in short-HSCR). Phasing RVs with the RET HSCR-associated haplotype suggests that RVs do not underlie the undisputable association of RET common variants with HSCR. None of the variants were found in 250 Chinese controls.
PLoS ONE 01/2011; 6(12):e28986. · 4.09 Impact Factor
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Maria-Mercè Garcia-Barceló,
Ming-Yiu Yeung,
Xiao-Ping Miao,
Clara Sze-Man Tang,
Guo Cheng,
Guo Chen,
Man-Ting So, Elly Sau-Wai Ngan,
Vincent Chi-Hang Lui,
Yan Chen, [......],
Kin-Wai Chan,
Xuan-Zhao Wu,
You-Qiang Song,
Danny Chan,
Kenneth Cheung,
Patrick Ho-Yu Chung,
Kenneth Kak-Yuen Wong,
Pak-Chung Sham,
Stacey S Cherny,
Paul Kwong-Hang Tam
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ABSTRACT: Biliary atresia (BA) is characterized by the progressive fibrosclerosing obliteration of the extrahepatic biliary system during the first few weeks of life. Despite early diagnosis and prompt surgical intervention, the disease progresses to cirrhosis in many patients. The current theory for the pathogenesis of BA proposes that during the perinatal period, a still unknown exogenous factor meets the innate immune system of a genetically predisposed individual and induces an uncontrollable and potentially self-limiting immune response, which becomes manifest in liver fibrosis and atresia of the extrahepatic bile ducts. Genetic factors that could account for the disease, let alone for its high incidence in Chinese, are to be investigated. To identify BA susceptibility loci, we carried out a genome-wide association study (GWAS) using the Affymetrix 5.0 and 500 K marker sets. We genotyped nearly 500 000 single-nucleotide polymorphisms (SNPs) in 200 Chinese BA patients and 481 ethnically matched control subjects. The 10 most BA-associated SNPs from the GWAS were genotyped in an independent set of 124 BA and 90 control subjects. The strongest overall association was found for rs17095355 on 10q24, downstream XPNPEP1, a gene involved in the metabolism of inflammatory mediators. Allelic chi-square test P-value for the meta-analysis of the GWAS and replication results was 6.94 x 10(-9). The identification of putative BA susceptibility loci not only opens new fields of investigation into the mechanisms underlying BA but may also provide new clues for the development of preventive and curative strategies.
Human Molecular Genetics 05/2010; 19(14):2917-25. · 7.64 Impact Factor
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ABSTRACT: Receptor tyrosine kinase (RET) single nucleotide polymorphisms (SNPs) are associated with the Hirschsprung's disease (HSCR). We investigated whether the amount of RET expressed in the ganglionic gut of human was dependent on the genotype of three regulatory SNPs (-5G>A rs10900296 and -1A>C rs10900297 in the promoter, and C>T rs2435357 in intron 1). We examined the effects of three regulatory SNPs on the RET gene expression in 67 human ganglionic gut tissues using quantitative real-time PCR. Also, 315 Chinese HSCR patients and 325 ethnically matched controls were genotyped for the three SNPs by polymerase chain reaction (PCR) and direct sequencing. The expression of RET mRNA in human gut tissue did indeed correlate with the genotypes of the individuals. The lowest RET expression was found for those individuals homozygous for the three risk alleles (A-C-T/A-C-T), and the highest for those homozygous for the 'wild-type' counterpart (G-A-C/G-A-C), with expression values ranging from 218.32 +/- 125.69 (mean +/- SE) in tissues from individuals carrying G-A-C/G-A-C to 31.42 +/- 8.42 for individuals carrying A-C-T/A-C-T (P = 0.018). As expected, alleles -5A, -1C and intron 1 T were associated with HSCR (P = 5.94 x 10(-31), 3.12 x 10(-24) and 5.94 x 10(-37), respectively) as was the haplotype encompassing the three associated alleles (A-C-T) when compared with the wild-type counterpart G-A-C (chi2 = 155.29, P < 0.0001). To our knowledge, this is the first RET expression genotype-phenotype correlation study conducted on human subjects to indicate common genetic variants in the regulatory region of RET may play a role in mediating susceptibility to HSCR, by conferring a significant reduction of the RET expression.
Human Molecular Genetics 04/2010; 19(8):1461-7. · 7.64 Impact Factor
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Xiaoping Miao,
Maria-Mercè Garcia-Barceló,
Man-ting So,
Wai-kiu Tang,
Xiao Dong,
Bin Wang,
Jianxiong Mao, Elly Sau-wai Ngan,
Yan Chen,
Vincent Chi-hang Lui,
Kenneth Kak-yuen Wong,
Lei Liu,
Paul Kwong-hang Tam
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ABSTRACT: Infantile hypertrophic pyloric stenosis (IHPS) is one of the most common gastrointestinal obstructions in the infancy requiring surgery. Reduced expression of neuronal nitric oxide synthase (nNOS), which plays an important role in the regulation of the human pyloric muscle, is thought to underlie IHPS. The role of nNOS in IHPS has been supported by the genetic association of a functional regulatory nNOS polymorphism (-84G>A) with IHPS in whites. We reasoned that the corroboration of this association in a population of different ethnic origin would prompt follow-up studies and further investigation of the IHPS pathology at molecular level. Thus, we attempted to reproduce the original findings in a Chinese population of comparable size in what would be the first genetic study on IHPS conducted in Chinese.
nNOS -84G>A genotypes were analyzed in 56 patients and 86 controls by polymerase chain reaction and DNA sequencing. Logistic regression was used to compute odds ratios.
Our study could not corroborate the association previously reported. Although the frequency of the IHPS-associated allele (-84A) in controls (0.205) was similar to that reported for white controls, there was a dramatic difference in -84A frequencies between white and Chinese patients (0.198). Similarly, there was no difference in the nNOS -84G>A genotype distribution between patients and controls, even when the GA and AA genotypes were combined to compare GG genotype (odds ratio, 1.01; 95% confidence interval, 0.47-2.19).
Failure to replicate the initial finding does not detract from its validity, because genetic effects may differ across populations. Differences across populations in linkage disequilibrium and/or allele frequencies may contribute to this lack of replication. The role nNOS in IHPS awaits further investigation.
Journal of Pediatric Surgery 04/2010; 45(4):709-13. · 1.45 Impact Factor
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Maria-Mercè Garcia-Barceló,
Vincent Chi-Hang Lui,
Man-ting So,
Xiaoping Miao,
Thomas Yuk-yu Leon,
Zhen-wei Yuan, Elly Sau-wai Ngan,
Toufique Ehsan,
Patrick Ho-yu Chung,
Pek-lan Khong,
Kenneth Kak-yuen Wong,
Paul Kwong-hang Tam
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ABSTRACT: The combination of partial absence of the sacrum, anorectal anomalies, and presacral mass constitutes Currarino syndrome (CS), which is associated with mutations in MNX1 motor neuron and pancreas homeobox 1 (previously HLXB9). Here, we report on the MNX1 mutations found in a family segregating CS and in 3 sporadic CS patients, as well as on the clinical characteristics of the affected individuals.
MNX1 mutations were identified by direct sequencing the coding regions, intron/exon boundaries of MNX1 in 5 CS Japanese family members and 3 Chinese sporadic cases and their parents.
There were 2 novel (P18PfsX37, R243W) and 2 previously described (W288G and IVS2 + 1G > A) mutations. These mutations were not found in 198 control individuals and are predicted to impair the functioning of the MNX1 protein.
The variability of the CS phenotype among related or unrelated patients bearing the same mutation advocates for differences in the genetic background of each individual and invokes the implication of additional CS susceptibility genes.
Journal of Pediatric Surgery 10/2009; 44(10):1892-8. · 1.45 Impact Factor
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Maria-Mercè Garcia-Barcelo,
Clara Sze-Man Tang, Elly Sau-Wai Ngan,
Vincent Chi-Hang Lui,
Yan Chen,
Man-Ting So,
Thomas Yuk-Yu Leon,
Xiao-Ping Miao,
Cathy Ka-Yee Shum,
Feng-Qin Liu, [......],
Xiao-Bing Sun,
Liu-Ming Huang,
Jin-Fa Tou,
You-Qiang Song,
Danny Chan,
Kenneth M C Cheung,
Kenneth Kak-Yuen Wong,
Stacey S Cherny,
Pak-Chung Sham,
Paul Kwong-Hang Tam
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[hide abstract]
ABSTRACT: Hirschsprung's disease (HSCR), or aganglionic megacolon, is a congenital disorder characterized by the absence of enteric ganglia in variable portions of the distal intestine. RET is a well-established susceptibility locus, although existing evidence strongly suggests additional loci contributing to sporadic HSCR. To identify these additional genetic loci, we carried out a genome-wide association study using the Affymetrix 500K marker set. We successfully genotyped 293,836 SNPs in 181 Chinese subjects with sporadic HSCR and 346 ethnically matched control subjects. The SNPs most associated with HSCR were genotyped in an independent set of 190 HSCR and 510 control subjects. Aside from SNPs in RET, the strongest overall associations in plausible candidate genes were found for 2 SNPs located in intron 1 of the neuregulin1 gene (NRG1) on 8p12, with rs16879552 and rs7835688 yielding odds ratios of 1.68 [CI(95%):(1.40, 2.00), P = 1.80 x 10(-8)] and 1.98 [CI(95%):(1.59, 2.47), P = 1.12 x 10(-9)], respectively, for the heterozygous risk genotypes under an additive model. There was also a significant interaction between RET and NRG1 (P = 0.0095), increasing the odds ratio 2.3-fold to 19.53 for the RET rs2435357 risk genotype (TT) in the presence of the NRG1 rs7835688 heterozygote, indicating that NRG1 is a modifier of HSRC penetrance. Our highly significant association findings are backed-up by the important role of NRG1 as regulator of the development of the enteric ganglia precursors. The identification of NRG1 as an additional HSCR susceptibility locus not only opens unique fields of investigation into the mechanisms underlying the HSCR pathology, but also the mechanisms by which a discrete number of loci interact with each other to cause disease.
Proceedings of the National Academy of Sciences 03/2009; 106(8):2694-9. · 9.68 Impact Factor
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ABSTRACT: VACTERL acronym is assigned to a non-random association of malformations in humans with poorly known etiology. It is comprised of vertebral defects (V), anal atresia (A), cardiac anomaly (C), tracheoesophageal fistula with esophageal atresia (TE), renal dysplasia (R) and limb lesions (L). Here, we report on, for the first time, a female patient with VACTERL association with a 21 base-pair deletion in the exon 1 triplet repeats of HOXD13, a sonic hedgehog (SHH) downstream target. Our data provide the first piece of clinical evidence of the implication of the SHH pathway in VACTERL. Moreover, HOXD13 may not only be implicated in limb malformations but also in the development of gut and genitourinary structures, as predicted from the mouse models.
American Journal of Medical Genetics Part A 12/2008; 146A(24):3181-5. · 2.39 Impact Factor
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K Y-K Chan,
W Liu,
J-R Long,
S-P Yip,
S-Y Chan,
X-O Shu,
D T-T Chua,
A N-Y Cheung,
J C-Y Ching,
H Cai,
G K-H Au,
M Chan,
W Foo,
H Y-S Ngan,
Y-T Gao, E S-W Ngan,
M-M Garcia-Barceló,
Wei Zheng,
U-S Khoo
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ABSTRACT: The BRCA1 gene is an important breast-cancer susceptibility gene. Promoter polymorphisms can alter the binding affinity of transcription factors, changing transcriptional activity and may affect susceptibility to disease.
Using direct sequencing of the BRCA1 promoter region, we identified four polymorphisms c.-2804T-->C (rs799908:T-->C), c.-2265C-->T (rs11655505:C-->T), c.-2004A-->G (rs799906:A-->G) and c.-1896(ACA)(1)-->(ACA)(2) (rs8176071:(ACA)(1)-->(ACA)(2)) present in Hong Kong Chinese. Each polymorphism was studied independently and in combination by functional assays. Although all four variants significantly altered promoter activity, the c.-2265T allele had stronger binding than the C allele, and the most common mutant haplotype, which contains the c.-2265T allele, increased promoter activity by 70%. Risk association first tested in Hong Kong Chinese women with breast cancer and age-matched controls and replicated in a large population-based study of Shanghai Chinese, together totalling >3000 participants, showed that carriers of the c.-2265T allele had a reduced risk for breast cancer (combined odd ratio (OR) = 0.80, 95% CI 0.69 to 0.93; p = 0.003) which was more evident among women aged >or=45 years at first diagnosis of breast cancer and without a family history of breast cancer (combined OR = 0.75, 95% CI 0.61 to 0.91; p = 0.004). The most common haplotype containing the c.-2265T allele also showed significant risk association for women aged >or=45 years without a family history of breast cancer (OR = 0.64, 95% CI 0.46 to 0.89; p = 0.008).
This comprehensive study of BRCA1 promoter polymorphisms found four variants that altered promoter activity and with the most significant contribution from c.-2265C-->T, which could affect susceptibility to breast cancer in the Chinese population. Its significance in other populations remains to be investigated.
Journal of Medical Genetics 10/2008; 46(1):32-9. · 6.36 Impact Factor
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Maria-Mercè Garcia-Barceló,
Vincent Chi-Hang Lui,
Xiaoping Miao,
Man-ting So,
Thomas Yuk-yu Leon,
Zhen-wei Yuan,
Long Li,
Lei Liu,
Bin Wang,
Xiao-bing Sun,
Liu-Ming Huang,
Jin-fa Tou, Elly Sau-wai Ngan,
Stacey S Cherny,
Kin-wai Chan,
Kim-hung Lee,
Weiling Wang,
Kenneth Kak-yuen Wong,
Paul Kwong-hang Tam
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ABSTRACT: Anorectal malformations (congenital absence of the anal opening) are among the most common pediatric surgical problems and carry a significant chronic morbidity.
Direct sequencing was used to screen 88 anorectal malformations patients for mutations and polymorphisms in SHH and GLI3. These genes were chosen according to the phenotype presented by mutant mice and their expression patterns.
We report on 10 GLI3 variants (IVS3+141C>G, T183A, IVS4+124T>C, IVS7+17G>A, IVS8+1 G>C, N503N, P941P, P998L, A1005A, A1039A) and four SHH mutation/variants (IVS1-49C>T, IVS2+111A>C, L214L, G290D).
These variants are not over-represented in the healthy population and most are predicted to be benign. This study conveys the problematic assessment of the pathogenic role in disease of rare point mutations and variants.
Birth Defects Research Part A Clinical and Molecular Teratology 09/2008; 82(9):644-8. · 2.27 Impact Factor
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Maria-Mercè Garcia-Barceló,
Pui-yee Fong,
Clara S Tang,
Xiao-ping Miao,
Man-ting So,
Zhen-wei Yuan,
Long Li,
Wei-hong Guo,
Lei Liu,
Bin Wang,
Xiao-Bing Sun,
Liu-Ming Huang,
Jin-Fa Tou,
Kenneth Kak-Yuen Wong, Elly Sau-Wai Ngan,
Vincent Chi-hang Lui,
Stacey S Cherny,
Pak-chung Sham,
Paul Kwong-hang Tam
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ABSTRACT: Hirschsprung's disease (HSCR) is a congenital disorder in which ganglion cells are absent in variable portions of the lower digestive tract according to which patients are classified. The RET gene is the major HSCR gene, although reduced penetrance of RET mutations and variable expression of HSCR phenotype indicates that more than one gene is required. An unidentified RET-dependent modifier on 3p21 appears to be necessary for transmission of the short HSCR (S-HSCR) phenotype. We investigated 6 Mb of the 3p21 region on a quest for the HSCR-susceptibility locus. Fifty-eight S-HSCR case-parent trios were genotyped using Sequenom technology for 214 tag single nucleotide polymorphisms (SNPs) distributed along 6 Mb of the 3p21 region. A five-marker haplotype, spanning a 118 kb gene-rich region, was found to be overtransmitted to affected offspring. The associated haplotype encompasses three genes involved in neurological phenotypes. Importantly, this association was replicated in an independent sample of 172 S-HSCR cases and 153 unrelated controls. Ranking markers by proximity to candidate genes or by expected functional consequences could be used in follow-up studies to finally pinpoint this HSCR locus.
European Journal of HumanGenetics 08/2008; 16(7):833-40. · 4.40 Impact Factor
