Displaying publications 1 - 20 of 91 in total

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  1. Tan AH, Low SC, Tan CY, Lim KS, Tan CT, Lim SY
    Parkinsonism Relat Disord, 2016 11;32:137-139.
    PMID: 27688197 DOI: 10.1016/j.parkreldis.2016.09.019
  2. Closas AMFD, Lohmann K, Tan AH, Ibrahim NM, Lim JL, Tay YW, et al.
    J Mov Disord, 2023 Jan;16(1):91-94.
    PMID: 36537064 DOI: 10.14802/jmd.22109
    KMT2B-linked dystonia (DYT-KMT2B) is a childhood-onset dystonia syndrome typically beginning in the lower limbs and progressing caudocranially to affect the upper limbs with eventual prominent craniocervical involvement. Despite its recent recognition, it now appears to be one of the more common monogenic causes of dystonia syndromes. Here, we present an atypical case of DYT-KMT2B with oromandibular dystonia as the presenting feature, which remained restricted to this region three decades after symptom onset. This appears to be the first reported case of DYT-KMT2B from Southeast Asia and provides further supporting evidence for the pathogenic impact of the KMT2B c.6210_6213delTGAG variant.
  3. Lim SY, Tan AH, Ahmad-Annuar A, Schneider SA, Bee PC, Lim JL, et al.
    J Mov Disord, 2018 May;11(2):89-92.
    PMID: 29860786 DOI: 10.14802/jmd.17082
    We present a case of beta-propeller protein-associated neurodegeneration, a form of neurodegeneration with brain iron accumulation. The patient harbored a novel mutation in the WDR45 gene. A detailed video and description of her clinical condition are provided. Her movement disorder phenomenology was characterized primarily by limb stereotypies and gait dyspraxia. The patient's disability was advanced by the time iron-chelating therapy with deferiprone was initiated, and no clinical response in terms of cognitive function, behavior, speech, or movements were observed after one year of treatment.
  4. Lim SY, Ishiura H, Ramli N, Shibata S, Almansour MA, Tan AH, et al.
    Parkinsonism Relat Disord, 2020 05;74:25-27.
    PMID: 32289521 DOI: 10.1016/j.parkreldis.2020.03.025
    Two ethnic Chinese men with clinico-radiologic features of Fragile X-associated tremor-ataxia syndrome (FXTAS) were found on genetic testing to have neuronal intranuclear inclusion disease (NIID), highlighting that NIID should be considered in the differential diagnosis of FXTAS. NIID may also be much more common than FXTAS in certain Asian populations.
  5. Tan AH, Hew YC, Lim SY, Ramli NM, Kamaruzzaman SB, Tan MP, et al.
    Parkinsonism Relat Disord, 2018 11;56:58-64.
    PMID: 29914840 DOI: 10.1016/j.parkreldis.2018.06.020
    INTRODUCTION: Low body weight in Parkinson's disease (PD) is poorly understood despite the associated risks of malnutrition, fractures, and death. Sarcopenia (loss of muscle bulk and strength) and frailty are geriatric syndromes that are likewise associated with adverse health outcomes, yet have received scant attention in PD. We studied body composition, sarcopenia, frailty, and their clinico-biological correlates in PD.

    METHODS: 93 patients and 78 spousal/sibling controls underwent comprehensive assessment of diet, clinical status, muscle strength/performance, frailty, body composition (using dual-energy X-ray absorptiometry), and serum levels of neurogastrointestinal hormones and inflammatory markers.

    RESULTS: PD patients were older than controls (66.0 ± 8.5 vs. 62.4 ± 8.4years, P = 0.003). Mean body mass index (24.0 ± 0.4 vs. 25.6 ± 0.5kg/m2, Padjusted = 0.016), fat mass index (7.4 ± 0.3 vs. 9.0 ± 0.3kg/m2, Padjusted<0.001), and whole-body fat percentage (30.7 ± 0.8 vs. 35.7 ± 0.9%, Padjusted<0.001) were lower in patients, even after controlling for age and gender. There were no between-group differences in skeletal muscle mass index and whole-body bone mineral density. Body composition parameters did not correlate with disease duration or motor severity. Reduced whole-body fat percentage was associated with higher risk of motor response complications as well as higher levels of insulin-growth factor-1 and inflammatory markers. PD patients had a higher prevalence of sarcopenia (17.2% vs. 10.3%, Padjusted = 0.340) and frailty (69.4% vs. 24.2%, Padjusted = 0.010). Older age and worse PD motor severity were predictors of frailty in PD.

    CONCLUSIONS: We found reduced body fat with relatively preserved skeletal muscle mass, and a high prevalence of frailty, in PD. Further studies are needed to understand the patho-mechanisms underlying these alterations.

  6. Tan AH, Chong CW, Song SL, Teh CSJ, Yap IKS, Loke MF, et al.
    Mov Disord, 2018 01;33(1):174-176.
    PMID: 29083071 DOI: 10.1002/mds.27203
  7. Ariffin H, Chiew EKH, Oh BLZ, Lee SHR, Lim EH, Kham SKY, et al.
    J Clin Oncol, 2023 Jul 10;41(20):3642-3651.
    PMID: 37276496 DOI: 10.1200/JCO.22.02347
    PURPOSE: To investigate whether, for children with favorable-risk B-cell precursor ALL (BCP-ALL), an anthracycline-free protocol is noninferior to a modified Berlin-Frankfurt-Muenster ALL-IC2002 protocol, which includes 120 mg/m2 of anthracyclines.

    PATIENTS AND METHODS: Three hundred sixty-nine children with favorable-risk BCP-ALL (age 1-9 years, no extramedullary disease, and no high-risk genetics) who cleared minimal residual disease (≤0.01%) at the end of remission induction were enrolled into Ma-Spore (MS) ALL trials. One hundred sixty-seven standard-risk (SR) patients (34% of Malaysia-Singapore ALL 2003 study [MS2003]) were treated with the MS2003-SR protocol and received 120 mg/m2 of anthracyclines during delayed intensification while 202 patients (42% of MS2010) received an anthracycline-free successor protocol. The primary outcome was a noninferiority margin of 1.15 in 6-year event-free survival (EFS) between the MS2003-SR and MS2010-SR cohorts.

    RESULTS: The 6-year EFS of MS2003-SR and MS2010-SR (anthracycline-free) cohorts was 95.2% ± 1.7% and 96.5% ± 1.5%, respectively (P = .46). The corresponding 6-year overall survival was 97.6% and 99.0% ± 0.7% (P = .81), respectively. The cumulative incidence of relapse was 3.6% and 2.6%, respectively (P = .42). After adjustment for race, sex, age, presenting WBC, day 8 prednisolone response, and favorable genetic subgroups, the hazard ratio for MS2010-SR EFS was 0.98 (95% CI, 0.84 to 1.14; P = .79), confirming noninferiority. Compared with MS2003-SR, MS2010-SR had significantly lower episodes of bacteremia (30% v 45.6%; P = .04) and intensive care unit admissions (1.5% v 9.5%; P = .004).

    CONCLUSION: In comparison with MS2003-SR, the anthracycline-free MS2010-SR protocol is not inferior and was less toxic as treatment for favorable-risk childhood BCP-ALL.

  8. Lee SHR, Antillon-Klussmann F, Pei D, Yang W, Roberts KG, Li Z, et al.
    JAMA Oncol, 2022 Mar 01;8(3):354-363.
    PMID: 35084434 DOI: 10.1001/jamaoncol.2021.6826
    IMPORTANCE: Racial and ethnic disparities persist in the incidence and treatment outcomes of childhood acute lymphoblastic leukemia (ALL). However, there is a paucity of data describing the genetic basis of these disparities, especially in association with modern ALL molecular taxonomy and in the context of contemporary treatment regimens.

    OBJECTIVE: To evaluate the association of genetic ancestry with childhood ALL molecular subtypes and outcomes of modern ALL therapy.

    DESIGN, SETTING, AND PARTICIPANTS: This multinational, multicenter genetic association study was conducted from March 1, 2000, to November 20, 2020, among 2428 children and adolescents with ALL enrolled in frontline trials from the United States, South East Asia (Singapore and Malaysia), and Latin America (Guatemala), representing diverse populations of European, African, Native American, East Asian, and South Asian descent. Statistical analysis was conducted from February 3, 2020, to April 19, 2021.

    MAIN OUTCOMES AND MEASURES: Molecular subtypes of ALL and genetic ancestry were comprehensively characterized by performing RNA sequencing. Associations of genetic ancestries with ALL molecular subtypes and treatment outcomes were then evaluated.

    RESULTS: Among the participants in the study, 1340 of 2318 (57.8%) were male, and the mean (SD) age was 7.8 (5.3) years. Of 21 ALL subtypes identified, 8 were associated with ancestry. East Asian ancestry was positively associated with the frequency of somatic DUX4 (odds ratio [OR], 1.30 [95% CI, 1.16-1.45]; P 

  9. Lim JL, Ng EY, Lim SY, Tan AH, Abdul-Aziz Z, Ibrahim KA, et al.
    Neurol Sci, 2021 Oct;42(10):4203-4207.
    PMID: 33559030 DOI: 10.1007/s10072-021-05056-x
    BACKGROUND: Genome-wide association studies (GWAS) have shown that variants in the 3-methylcrotonyl-CoA carboxylase (MCCC1)/lysosome-associated membrane protein 3 (LAMP3) loci (rs10513789, rs12637471, rs12493050) reduce the risk of Parkinson's disease (PD) in Caucasians, Chinese and Ashkenazi-Jews while the rs11248060 variant in the diacylglycerol kinase theta (DGKQ) gene increases the risk of PD in Caucasian and Han Chinese cohorts. However, their roles in Malays are unknown. Therefore, this study aims to investigate the association of these variants with the risk of PD in individuals of Malay ancestry.

    METHODS: A total of 1114 subjects comprising of 536 PD patients and 578 healthy controls of Malay ancestry were recruited and genotyped using Taqman® allelic discrimination assays.

    RESULTS: The G allele of rs10513789 (OR = 0.83, p = 0.001) and A allele of rs12637471 (OR = 0.79, p = 0.007) in the MCCC1/LAMP3 locus were associated with a protective effect against developing PD in the Malay population. A recessive model of penetrance showed a protective effect of the GG genotype for rs10513789 and the AA genotype for rs12637471. No association with PD was found with the other MCCC1/LAMP3 rs12493050 variant or with the DGKQ (rs11248060) variant. No significant associations were found between the four variants with the age at PD diagnosis.

    CONCLUSION: MCCC1/LAMP3 variants rs10513789 and rs12637471 protect against PD in the Malay population.

  10. Suwarnalata G, Tan AH, Isa H, Gudimella R, Anwar A, Loke MF, et al.
    PLoS One, 2016;11(4):e0153725.
    PMID: 27100827 DOI: 10.1371/journal.pone.0153725
    Parkinson's disease (PD) is the second most common chronic and progressive neurodegenerative disorder. Its etiology remains elusive and at present only symptomatic treatments exists. Helicobacter pylori chronically colonizes the gastric mucosa of more than half of the global human population. Interestingly, H. pylori positivity has been found to be associated with greater of PD motor severity. In order to investigate the underlying cause of this association, the Sengenics Immunome protein array, which enables simultaneous screening for autoantibodies against 1636 human proteins, was used to screen the serum of 30 H. pylori-seropositive PD patients (case) and 30 age- and gender-matched H. pylori-seronegative PD patients (control) in this study. In total, 13 significant autoantibodies were identified and ranked, with 8 up-regulated and 5 down-regulated in the case group. Among autoantibodies found to be elevated in H. pylori-seropositive PD were included antibodies that recognize Nuclear factor I subtype A (NFIA), Platelet-derived growth factor B (PDGFB) and Eukaryotic translation initiation factor 4A3 (eIFA3). The presence of elevated autoantibodies against proteins essential for normal neurological functions suggest that immunomodulatory properties of H. pylori may explain the association between H. pylori positivity and greater PD motor severity.
  11. Lim SY, Lim KB, Hor JW, Tan AH
    Mov Disord, 2020 10;35(10):1884-1885.
    PMID: 33068479 DOI: 10.1002/mds.28274
  12. Lam JC, Chai JY, Wong YL, Tan NW, Ha CT, Chan MY, et al.
    Ann Acad Med Singap, 2015 Nov;44(11):530-4.
    PMID: 27089960
    INTRODUCTION: Treatment of acute lymphoblastic leukaemia (ALL) using intensive chemotherapy has resulted in high cure rates but also substantial morbidity. Infective complications represent a significant proportion of treatment-related toxicity. The objective of this study was to describe the microbiological aetiology and clinical outcome of episodes of chemotherapy-induced febrile neutropaenia in a cohort of children treated for ALL at our institution.

    MATERIALS AND METHODS: Patients with ALL were treated with either the HKSGALL93 or the Malaysia-Singapore (Ma-Spore) 2003 chemotherapy protocols. The records of 197 patients who completed the intensive phase of treatment, defined as the period of treatment from induction, central nervous system (CNS)-directed therapy to reinduction from June 2000 to January 2010 were retrospectively reviewed.

    RESULTS: There were a total of 587 episodes of febrile neutropaenia in 197 patients, translating to an overall rate of 2.98 episodes per patient. A causative pathogen was isolated in 22.7% of episodes. An equal proportion of Gram-positive bacteria (36.4%) and Gram-negative bacteria (36.4%) were most frequently isolated followed by viral pathogens (17.4%), fungal pathogens (8.4%) and other bacteria (1.2%). Fungal organisms accounted for a higher proportion of clinically severe episodes of febrile neutropaenia requiring admission to the high-dependency or intensive care unit (23.1%). The overall mortality rate from all episodes was 1.5%.

    CONCLUSION: Febrile neutropaenia continues to be of concern in ALL patients undergoing intensive chemotherapy. The majority of episodes will not have an identifiable causative organism. Gram-positive bacteria and Gram-negative bacteria were the most common causative pathogens identified. With appropriate antimicrobial therapy and supportive management, the overall risk of mortality from febrile neutropaenia is extremely low.

  13. Tan AH, Toh TH, Low SC, Fong SL, Chong KK, Lee KW, et al.
    J Mov Disord, 2018 Sep;11(3):149-151.
    PMID: 30086616 DOI: 10.14802/jmd.18017
  14. Lim SY, Lim JL, Ahmad-Annuar A, Lohmann K, Tan AH, Lim KB, et al.
    Neurodegener Dis, 2020;20(1):39-45.
    PMID: 32580205 DOI: 10.1159/000508131
    Pathogenic and risk variants in the LRRK2 gene are among the main genetic contributors to Parkinson's disease (PD) worldwide, and LRRK2-targeted therapies for patients with PARK-LRRK2are now entering clinical trials. However, in contrast to the LRRK2 G2019S mutation commonly found in Caucasians, North-African Arabs, and Ashkenazi Jews, relatively little is known about other causative LRRK2 mutations, and data on genotype-phenotype correlations are largely lacking. This report is from an ongoing multicentre study in which next-generation sequencing-based PD gene panel testing has so far been conducted on 499 PD patients of various ethnicities from Malaysia. We describe 2 sisters of Chinese ancestry with PD who carry the R1441C mutation in LRRK2 (which in Asians has been reported in only 2 Chinese patients previously), and highlight interesting clinical observations made over a decade of close follow-up. We further explored the feasibility of using a brief, expert-administered rating scale (the Clinical Impression of Severity Index; CISI-PD) to capture data on global disease severity in a large (n = 820) unselected cohort of PD patients, including severely disabled individuals typically excluded from research studies. All patients in this study were managed and evaluated by the same PD neurologist, and these data were used to make broad comparisons between the monogenic PD cases versus the overall "real world" PD cohort. This report contributes to the scarce literature on R1441C PARK-LRRK2, offering insights into natural history and epidemiological aspects, and provides support for the application of a simple and reliable clinical tool that can improve the inclusion of under-represented patient groups in PD research.
  15. Rashidah NH, Lim SM, Neoh CF, Majeed ABA, Tan MP, Khor HM, et al.
    Ageing Res Rev, 2022 Dec;82:101744.
    PMID: 36202312 DOI: 10.1016/j.arr.2022.101744
    This systematic review appraised previous findings on differential gut microbiota composition and intestinal permeability markers between frail and healthy older adults. A literature search was performed using PubMed, Scopus, ScienceDirect and the Cochrane Library. Relevant studies were shortlisted based on inclusion and exclusion criteria as well as assessed for risk of bias. The primary outcome was the differential composition of gut microbiota and/ or intestinal permeability markers between frail and healthy older adults. A total of 10 case-control studies and one cohort study were shortlisted. Based on consistent findings reported by more than one shortlisted study, the microbiota of frail older adults was characterised by decreased phylum Firmicutes, with Dialister, Lactobacillus and Ruminococcus being the prominent genera. Healthy controls, on the other hand, exhibited higher Eubacterium at the genera level. In terms of intestinal permeability, frail older adults were presented with increased serum zonulin, pro-inflammatory cytokines (TNF-α, HMGB-1, IL-6, IL1-ra, MIP-1β) and amino acids (aspartic acid and phosphoethanolamine) when compared to healthy controls. Altogether, frail elderlies had lower gut microbiota diversity and lower abundance of SCFA producers, which may have led to leaky guts, upregulated pro-inflammatory cytokines, frailty and sarcopenia.
  16. Li Z, Lee SHR, Chin WHN, Lu Y, Jiang N, Lim EH, et al.
    Blood Adv, 2021 12 14;5(23):5226-5238.
    PMID: 34547766 DOI: 10.1182/bloodadvances.2021004895
    Among the recently described subtypes in childhood B-lymphoblastic leukemia (B-ALL) were DUX4- and PAX5-altered (PAX5alt). By using whole transcriptome RNA sequencing in 377 children with B-ALL from the Malaysia-Singapore ALL 2003 (MS2003) and Malaysia-Singapore ALL 2010 (MS2010) studies, we found that, after hyperdiploid and ETV6-RUNX1, the third and fourth most common subtypes were DUX4 (n = 51; 14%) and PAX5alt (n = 36; 10%). DUX4 also formed the largest genetic subtype among patients with poor day-33 minimal residual disease (MRD; n = 12 of 44). But despite the poor MRD, outcome of DUX4 B-ALL was excellent (5-year cumulative risk of relapse [CIR], 8.9%; 95% confidence interval [CI], 2.8%-19.5% and 5-year overall survival, 97.8%; 95% CI, 85.3%-99.7%). In MS2003, 21% of patients with DUX4 B-ALL had poor peripheral blood response to prednisolone at day 8, higher than other subtypes (8%; P = .03). In MS2010, with vincristine at day 1, no day-8 poor peripheral blood response was observed in the DUX4 subtype (P = .03). The PAX5alt group had an intermediate risk of relapse (5-year CIR, 18.1%) but when IKZF1 was not deleted, outcome was excellent with no relapse among 23 patients. Compared with MS2003, outcome of PAX5alt B-ALL with IKZF1 codeletion was improved by treatment intensification in MS2010 (5-year CIR, 80.0% vs 0%; P = .05). In conclusion, despite its poor initial response, DUX4 B-ALL had a favorable overall outcome, and the prognosis of PAX5alt was strongly dependent on IKZF1 codeletion.
  17. Yeoh AE, Li Z, Dong D, Lu Y, Jiang N, Trka J, et al.
    Br J Haematol, 2018 Jun;181(5):653-663.
    PMID: 29808917 DOI: 10.1111/bjh.15252
    Accurate risk assignment in childhood acute lymphoblastic leukaemia is essential to avoid under- or over-treatment. We hypothesized that time-series gene expression profiles (GEPs) of bone marrow samples during remission-induction therapy can measure the response and be used for relapse prediction. We computed the time-series changes from diagnosis to Day 8 of remission-induction, termed Effective Response Metric (ERM-D8) and tested its ability to predict relapse against contemporary risk assignment methods, including National Cancer Institutes (NCI) criteria, genetics and minimal residual disease (MRD). ERM-D8 was trained on a set of 131 patients and validated on an independent set of 79 patients. In the independent blinded test set, unfavourable ERM-D8 patients had >3-fold increased risk of relapse compared to favourable ERM-D8 (5-year cumulative incidence of relapse 38·1% vs. 10·6%; P = 2·5 × 10-3 ). ERM-D8 remained predictive of relapse [P = 0·05; Hazard ratio 4·09, 95% confidence interval (CI) 1·03-16·23] after adjusting for NCI criteria, genetics, Day 8 peripheral response and Day 33 MRD. ERM-D8 improved risk stratification in favourable genetics subgroups (P = 0·01) and Day 33 MRD positive patients (P = 1·7 × 10-3 ). We conclude that our novel metric - ERM-D8 - based on time-series GEP after 8 days of remission-induction therapy can independently predict relapse even after adjusting for NCI risk, genetics, Day 8 peripheral blood response and MRD.
  18. Lange LM, Avenali M, Ellis M, Illarionova A, Keller Sarmiento IJ, Tan AH, et al.
    NPJ Parkinsons Dis, 2023 Jun 27;9(1):100.
    PMID: 37369645 DOI: 10.1038/s41531-023-00526-9
    The Monogenic Network of the Global Parkinson's Genetics Program (GP2) aims to create an efficient infrastructure to accelerate the identification of novel genetic causes of Parkinson's disease (PD) and to improve our understanding of already identified genetic causes, such as reduced penetrance and variable clinical expressivity of known disease-causing variants. We aim to perform short- and long-read whole-genome sequencing for up to 10,000 patients with parkinsonism. Important features of this project are global involvement and focusing on historically underrepresented populations.
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