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Fulltext Oxygen isotopes in orangutan teeth reveal recent and ancient climate variation

Smith TM, Arora M, Austin C, Nunes Ávila J, Duval M, Lim TT, et al.

Elife, 2024 Mar 08;12.
PMID: 38457350 DOI: 10.7554/eLife.90217

Studies of climate variation commonly rely on chemical and isotopic changes recorded in sequentially produced growth layers, such as in corals, shells, and tree rings, as well as in accretionary deposits-ice and sediment cores, and speleothems. Oxygen isotopic compositions (δ18O) of tooth enamel are a direct method of reconstructing environmental variation experienced by an individual animal. Here, we utilize long-forming orangutan dentitions (Pongo spp.) to probe recent and ancient rainfall trends on a weekly basis over ~3-11 years per individual. We first demonstrate the lack of any consistent isotopic enrichment effect during exclusive nursing, supporting the use of primate first molar teeth as environmental proxies. Comparisons of δ18O values (n=2016) in twelve molars from six modern Bornean and Sumatran orangutans reveal a high degree of overlap, with more consistent annual and bimodal rainfall patterns in the Sumatran individuals. Comparisons with fossil orangutan δ18O values (n=955 measurements from six molars) reveal similarities between modern and late Pleistocene fossil Sumatran individuals, but differences between modern and late Pleistocene/early Holocene Bornean orangutans. These suggest drier and more open environments with reduced monsoon intensity during this earlier period in northern Borneo, consistent with other Niah Caves studies and long-term speleothem δ18O records in the broader region. This approach can be extended to test hypotheses about the paleoenvironments that early humans encountered in southeast Asia.
Fulltext LRRK2 G2385R and R1628P mutations are associated with an increased risk of Parkinson's disease in the Malaysian population

Gopalai AA, Lim SY, Chua JY, Tey S, Lim TT, Mohamed Ibrahim N, et al.

Biomed Res Int, 2014;2014:867321.
PMID: 25243190 DOI: 10.1155/2014/867321

The LRRK2 gene has been associated with both familial and sporadic forms of Parkinson's disease (PD). The G2019S variant is commonly found in North African Arab and Caucasian PD patients, but this locus is monomorphic in Asians. The G2385R and R1628P variants are associated with a higher risk of developing PD in certain Asian populations but have not been studied in the Malaysian population. Therefore, we screened the G2385R and R1628P variants in 1,202 Malaysian subjects consisting of 695 cases and 507 controls. The G2385R and R1628P variants were associated with a 2.2-fold (P = 0.019) and 1.2-fold (P = 0.054) increased risk of PD, respectively. Our data concur with other reported findings in Chinese, Taiwanese, Singaporean, and Korean studies.
PARK16 is associated with PD in the Malaysian population

Gopalai AA, Ahmad-Annuar A, Li HH, Zhao Y, Lim SY, Tan AH, et al.

Am J Med Genet B Neuropsychiatr Genet, 2016 09;171(6):839-47.
PMID: 27174169 DOI: 10.1002/ajmg.b.32454

PARK16 was identified as a risk factor for Parkinson's disease in a Japanese cohort; however, subsequent studies in the other populations including the Chinese, European, Caucasian, and Chilean have shown a protective role instead. To investigate this locus in our Malaysian cohort, 1,144 individuals were screened for five SNPs in the PARK16 locus and logistic regression analysis showed that the A allele of the rs947211 SNP reduced the risk of developing PD via a recessive model (Odds ratio 0.57, P-value 0.0003). Pooled analysis with other Asian studies showed that A allele of the rs947211 SNP decreased the risk of developing PD via a recessive model (Odds ratio 0.71, P-value 0.0001). In addition, when meta-analysis was performed with other Asian population, three SNPs (rs823128, rs823156, and rs11240572) reduced risk of developing PD via a dominant model. © 2016 Wiley Periodicals, Inc.
Glucocerebrosidase (GBA) gene variants in a multi-ethnic Asian cohort with Parkinson's disease: mutational spectrum and clinical features

Lim JL, Lohmann K, Tan AH, Tay YW, Ibrahim KA, Abdul Aziz Z, et al.

J Neural Transm (Vienna), 2022 Jan;129(1):37-48.
PMID: 34779914 DOI: 10.1007/s00702-021-02421-0

GBA variants are associated with increased risk and earlier onset of Parkinson's disease (PD), and more rapid disease progression especially with "severe" variants typified by p.L483P. GBA mutation screening studies from South-East Asia, with > 650 million inhabitants of diverse ancestries, are very limited. We investigated the spectrum of GBA variants, and associated clinico-demographic features, in a multi-ethnic PD cohort in Malaysia. Patients (n = 496) were recruited from seven centres, primarily of Chinese (45%), Malay (37%), and Indian (13%) ethnicities. All GBA coding exons were screened using a next-generation sequencing-based PD gene panel and verified with Sanger sequencing. We identified 14 heterozygous GBA alleles consisting of altogether 17 missense variants (8 classified as pathogenic or likely pathogenic for PD) in 25 (5.0%) patients, with a substantially higher yield among early (
Fulltext LRRK2 N551K and R1398H variants are protective in Malays and Chinese in Malaysia: A case-control association study for Parkinson's disease

Gopalai AA, Lim JL, Li HH, Zhao Y, Lim TT, Eow GB, et al.

Mol Genet Genomic Med, 2019 Nov;7(11):e604.
PMID: 31487119 DOI: 10.1002/mgg3.604

BACKGROUND: The LRRK2 gene is associated with Parkinson's disease (PD) as a number of mutations within the gene have been shown to be susceptibility factors. Studies on various global populations have determined that mutations such as G2019S, G2385R, and R1628P in LRRK2 increase the risk of developing PD while the N551K-R1398H haplotype is associated with conferring protection against developing PD. Here we report a study looking at the N551K and R1398H variants for the first time in the Malaysian population.
METHODS: Cases (523) which conformed to the United Kingdom PD Brain Bank Criteria for PD were recruited through trained neurologists and age- and ethnically matched controls (491) were individuals free of any neurological disorder. The N551K and R1398H mutations were genotyped using the Taqman SNP genotyping assay.
RESULTS: A significant protective association for N551K was found in those of Malay ancestry, with a protective trend seen for R1398H. A meta-analysis of Chinese individuals in this cohort with other published cohorts of Chinese ancestry indicated a significant protective role for N551K and R1398H.
CONCLUSION: This study reports that the N551K-R1398H haplotype is also relevant to the Malaysian population, with a significant protective effect found in those of Malay and Chinese ancestries.
Movement disorders in Indochina: Resource challenges and future solutions

Bhidayasiri R, Sringean J, Van Le T, Lim TT, Navuth C, Phoumindr A, et al.

J Neural Transm (Vienna), 2023 Jul;130(7):875-889.
PMID: 37306791 DOI: 10.1007/s00702-023-02662-1

Movement disorders are a major cause of disability worldwide and their increasing prevalence predicts a substantial future burden of care. Impactful patient care requires availability of, and accessibility to, effective medications, knowledge, and disease awareness among both medical professionals and patients, driven by skilled personnel to harness and manage resources. The highest burden of movement disorders is in low-to-middle income countries where resources are often limited and infrastructure is insufficient to meet growing demands. This article focuses on the specific challenges faced in the management and delivery of care for movement disorders in Indochina, the mainland region of Southeast Asia comprising the neighboring countries of Cambodia, Laos, Malaysia, Myanmar, Thailand, and Vietnam. The first Indochina Movement Disorders Conference was held in August 2022 in Ho Chi Minh City, Vietnam, to provide a platform to better understand the situation in the region. Future management of movement disorders in Indochina will require progressive adaptation of existing practices to reflect modern approaches to care delivery. Digital technologies offer an opportunity to strengthen these processes and address the challenges identified in the region. Ultimately, a long-term collaborative approach by regional healthcare providers is key.
Lack of association between the LRRK2 A419V variant and Asian Parkinson's disease

Gopalai AA, Lim SY, Aziz ZA, Lim SK, Tan LP, Chong YB, et al.

Ann Acad Med Singap, 2013 May;42(5):237-40.
PMID: 23771111

INTRODUCTION: The G2385R and R1628P LRRK2 gene variants have been associated with an increased risk of Parkinson's disease (PD) in the Asian population. Recently, a new LRRK2 gene variant, A419V, was reported to be a third risk variant for PD in Asian patients. Our objective was to investigate this finding in our cohort of Asian subjects.
MATERIALS AND METHODS: Eight hundred and twenty-eight subjects (404 PD patients, and 424 age and gender-matched control subjects without neurological disorders) were recruited. Genotyping was done by Taqman® allelic discrimination assay on an Applied Biosystems 7500 Fast Real-Time PCR machine.
RESULTS: The heterozygous A419V genotype was found in only 1 patient with PD, compared to 3 in the control group (0.4% vs 1.3%), giving an odds ratio of 0.35 (95% confidence interval (CI), 0.01 to 3.79; P = 0.624).
CONCLUSION: A419V is not an important LRRK2 risk variant in our Asian cohort of patients with PD. Our data are further supported by a literature review which showed that 4 out of 6 published studies reported a negative association of this variant in PD.
Delivering patient-centered care in Parkinson's disease: Challenges and consensus from an international panel

Bhidayasiri R, Panyakaew P, Trenkwalder C, Jeon B, Hattori N, Jagota P, et al.

Parkinsonism Relat Disord, 2020 03;72:82-87.
PMID: 32146380 DOI: 10.1016/j.parkreldis.2020.02.013

An international panel of movement disorders specialists explored the views and perceptions of people with Parkinson's disease (PD) about their condition and its treatment, including the potential mismatch between the clinician's view of the patient's condition and their own view of what aspects of the disease most affect their daily lives. The initiative was focused on Asian countries, so participants comprised experts in the management of PD from key centers in Asia, with additional insight provided by European and the North American movement disorders experts. Analysis of peer-reviewed publications on patient perceptions of PD and the factors that they consider important to their wellbeing identified several contributing factors to the mismatch of views, including gaps in knowledge of PD and its treatment, an understanding of the clinical heterogeneity of PD, and the importance of a multidisciplinary approach to patient care. The faculty proposed options to bridge these gaps to ensure that PD patients receive the personalized treatment they need to achieve the best possible outcomes. It was considered essential to improve patient knowledge about PD and its treatment, as well as increasing the awareness of clinicians of PD heterogeneity in presentation and treatment response. A multidisciplinary and shared-care approach to PD was needed alongside the use of patient-centered outcome measures in clinical trials and clinical practice to better capture the patient experience and improve the delivery of individualized therapy.
Association study of MCCC1/LAMP3 and DGKQ variants with Parkinson's disease in patients of Malay ancestry

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.
Genetic study of early-onset Parkinson's disease in the Malaysian population

Tay YW, Tan AH, Lim JL, Lohmann K, Ibrahim KA, Abdul Aziz Z, et al.

Parkinsonism Relat Disord, 2023 Jun;111:105399.
PMID: 37209484 DOI: 10.1016/j.parkreldis.2023.105399

BACKGROUND: About 5-10% of Parkinson's disease (PD) cases are early onset (EOPD), with several genes implicated, including GBA1, PRKN, PINK1, and SNCA. The spectrum and frequency of mutations vary across populations and globally diverse studies are crucial to comprehensively understand the genetic architecture of PD. The ancestral diversity of Southeast Asians offers opportunities to uncover a rich PD genetics landscape, and identify common regional mutations and new pathogenic variants.
OBJECTIVES: This study aimed to investigate the genetic architecture of EOPD in a multi-ethnic Malaysian cohort.
METHODS: 161 index patients with PD onset ≤50 years were recruited from multiple centers across Malaysia. A two-step approach to genetic testing was used, combining a next-generation sequencing-based PD gene panel and multiplex ligation-dependent probe amplification (MLPA).
RESULTS: Thirty-five patients (21.7%) carried pathogenic or likely pathogenic variants involving (in decreasing order of frequency): GBA1, PRKN, PINK1, DJ-1, LRRK2, and ATP13A2. Pathogenic/likely pathogenic variants in GBA1 were identified in thirteen patients (8.1%), and were also commonly found in PRKN and PINK1 (11/161 = 6.8% and 6/161 = 3.7%, respectively). The overall detection rate was even higher in those with familial history (48.5%) or age of diagnosis ≤40 years (34.8%). PRKN exon 7 deletion and the PINK1 p.Leu347Pro variant appear to be common among Malay patients. Many novel variants were found across the PD-related genes.
CONCLUSIONS: This study provides novel insights into the genetic architecture of EOPD in Southeast Asians, expands the genetic spectrum in PD-related genes, and highlights the importance of diversifying PD genetic research to include under-represented populations.