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The association of mitochondrial DNA 5178 C > a polymorphism with plasma lipid levels among three ethnic groups

Lal S, Madhavan M, Heng CK

Ann. Hum. Genet., 2005 Nov;69(Pt 6):639-44.
PMID: 16266403

Mitochondria are eukaryotic cytoplasmic organelles responsible for oxidative phosphorylation. The C to A nucleotide transversion in the NADH dehydrogenase subunit 2 (MT-ND2) coding region of mitochondrial DNA has been reported to be associated with plasma lipid levels, adult onset diseases and longevity. We have examined the role of this polymorphism in relation to plasma lipid levels and age in a total of 713 healthy individuals belonging to 3 ethnic groups in Singapore. The frequency of the A allele was significantly higher (p < 0.05) among the Chinese (0.15) in comparison to the Malays (0.05) and Indians (0.02). No significant difference in the frequency of the allele was observed between healthy and coronary artery disease subjects, and between age-stratified subjects. We found that the polymorphism is significantly associated in an ethnic- and gender-specific manner with plasma apoB levels in the Chinese males (p < 0.05). This is the first epidemiological report of the mt5178 C > A polymorphism and its association with plasma lipid levels in Asian populations outside Japan.
The effects of three factor VII polymorphisms on factor VII coagulant levels in healthy Singaporean Chinese, Malay and Indian newborns

Quek SC, Low PS, Saha N, Heng CK

Ann. Hum. Genet., 2006 Nov;70(Pt 6):951-7.
PMID: 17044869

Factor VII (FVII) is an independent risk factor for coronary artery disease. Three polymorphisms of the factor VII gene (F7) were studied in a group of healthy newborns comprising 561 Chinese, 398 Malays and 226 Asian Indians from Singapore. The allele frequencies of 3 polymorphisms (R353Q, Promoter 0/10bp Del/Ins and Intron 7) in the FVII gene were ascertained through genotyping by polymerase chain reaction and restriction digestion of amplified fragments. In Chinese the minor allele frequencies are Q: 0.04, Ins: 0.03, R7: 0.44; Malays, Q: 0.06, Ins: 0.10, R7: 0.41; and Indians, Q: 0.25, Ins: 0.23, R7: 0.43. Strong linkage disequilibrium (Delta > 0.7) is observed between the 0/10 bp and the R353Q sites in all ethnic groups. We conclude that: (i) the prevalence of the minor Q and Ins alleles of the R353Q and 0/10 bp polymorphisms are significantly higher in the Indian newborns than the Chinese and Malays; (ii) the Q allele is significantly associated (p = 0.01) with a lower plasma FVII coagulant level in the Indian and Malay neonates; and this polymorphism explains up to 3.8% of the variance in FVII coagulant levels; (iii) there is no significant difference in allele frequencies of the three polymorphisms between neonates with and without family histories of CAD.
Genotype associations among seven apolipoprotein B polymorphisms in a population of Orang Asli of western Malaysia

Gajra B, Candlish JK, Heng CK, Mak JW, Saha N

Hum Biol, 1997 Oct;69(5):629-40.
PMID: 9299883

Associations among seven apolipoprotein B (APOB) gene polymorphisms [C-T promoter site; Leu-Ala-Leu signal peptide (SP) insertion/deletion; AG C,G site at codon 71; AG A1,D site at codon 591; XbaI site at codon 2488; AG H,I site at codon 3611; and AG T,Z site at codon 4154] were investigated in 195 members of an Orang Asli (aborigine) population from western Malaysia. Frequencies of the rare alleles for all these polymorphisms turned out to be low when compared with European but not Asian populations. The AG H,I site was not polymorphic. The highly polymorphic sites are in linkage disequilibrium among themselves, as shown by their delta values: SP 24,27 and AG C,G, 0.68; SP 24,27 and AG A1,D, 0.71; XbaI and AG C,G, 0.64; XbaI and AG A1,D, 0.57; SP 24,27 and XbaI, 0.48; and AG C,G and AG A1,D, 0.68. Ten unequivocal haplotypes on the basis of six sites (excluding the promoter polymorphism) were observed, and they represent 80% of the sample. The frequency of haplotype SP27,G,A1,X-,I,T, defined by the common homozygotes at all the sites for the APOB gene was 0.7, compared with 0.22 in Europeans. The ancestral haplotype SP27,G,D,X-,I,T was present at low frequency (0.01) in both the Orang Asli and Europeans. A cladogram constructed on the basis of haplotypes in the Orang Asli shows two different lines of evolution and that other haplotypes evolved by subsequent mutations on the ancestral haplotype.
Fulltext Detection of Helminth Eggs and Identification of Hookworm Species in Stray Cats, Dogs and Soil from Klang Valley, Malaysia

Tun S, Ithoi I, Mahmud R, Samsudin NI, Kek Heng C, Ling LY

PLoS One, 2015;10(12):e0142231.
PMID: 26671680 DOI: 10.1371/journal.pone.0142231

The present study was conducted to determine the prevalence of helminth eggs excreted in the faeces of stray cats, dogs and in soil samples. A total of 505 fresh samples of faeces (from 227 dogs and 152 cats) and soil were collected. The egg stage was detected via microscopy after the application of formalin-ether concentration technique. Genomic DNA was extracted from the samples containing hookworm eggs and used for further identification to the species level using real-time polymerase chain reaction coupled with high resolution melting analysis. Microscopic observation showed that the overall prevalence of helminth eggs among stray cats and dogs was 75.7% (95% CI = 71.2%-79.9%), in which 87.7% of dogs and 57.9% of cats were infected with at least one parasite genus. Five genera of heliminth eggs were detected in the faecal samples, including hookworms (46.4%), Toxocara (11.1%), Trichuris (8.4%), Spirometra (7.4%) and Ascaris (2.4%). The prevalence of helminth infections among stray dogs was significantly higher than that among stray cats (p < 0.001). Only three genera of helminths were detected in soil samples with the prevalence of 23% (95% CI = 15.1%-31%), consisting of hookworms (16.6%), Ascaris (4%) and Toxocara (2.4%). The molecular identification of hookworm species revealed that Ancylostoma ceylanicum was dominant in both faecal and soil samples. The dog hookworm, Ancylostoma caninum, was also detected among cats, which is the first such occurrence reported in Malaysia till date. This finding indicated that there was a cross-infection of A. caninum between stray cats and dogs because of their coexistent within human communities. Taken together, these data suggest the potential role of stray cats and dogs as being the main sources of environmental contamination as well as for human infections.
Thiopurine methyltransferase polymorphisms in a multiracial asian population and children with acute lymphoblastic leukemia

Kham SK, Tan PL, Tay AH, Heng CK, Yeoh AE, Quah TC

J Pediatr Hematol Oncol, 2002 Jun-Jul;24(5):353-9.
PMID: 12142782

The purpose of this study was to determine the frequency of thiopurine methyltransferase (TPMT) polymorphisms in a multiracial Asian population and to assess its relevance in the management of childhood acute lymphoblastic leukemia (ALL). Six hundred unrelated cord blood samples from 200 Chinese, Malay, and Indian healthy newborns were collected at the National University Hospital, Singapore; an additional 100 children with ALL were analyzed for five of the commonly reported TPMT variant alleles using polymerase chain reaction/restriction fragment length polymorphism and allele-specific polymerase chain reaction-based assays. In the cord blood study, the TPMT*3C variant was detected in all three ethnic groups; Chinese, Malays, and Indians had allele frequencies of 3%, 2.3%, and 0.8%, respectively. The TPMT*3A variant was found only among the Indians at a low allele frequency of 0.5%. The TPMT*6 variant was found in one Malay sample. Among the children with ALL, two white and one Chinese were heterozygous for the TPMT*3A variant and showed intermediate sensitivity to 6-mercaptopurine during maintenance therapy. Three Chinese patients and one Malay patient were heterozygous for the TPMT*3C variant. Mercaptopurine sensitivity could be validated in only one out of four TPMT*3C heterozygous patients. The overall allele frequency of the TPMT variants in this multiracial population was 2.5%. The TPMT*3C was the most common variant allele; TPMT*3A and TPMT*6 were rare. These results support the feasibility of performing TPMT genotyping in all children diagnosed with acute leukemia to minimize toxicity from thiopurine chemotherapy.
Perceptions of oral health among older Cambodians and their caregivers: A qualitative study

Horn R, Heng C, Chea C, Sieng C, Louv C, Turton B, et al.

Gerodontology, 2018 Mar;35(1):45-50.
PMID: 29226455 DOI: 10.1111/ger.12315

OBJECTIVE: Older adults (those above the age of 60) are an emerging demographic in Cambodia, and very little is understood about their oral health experiences, needs, perceptions and behaviours. The aim of this study was to explore the oral health experiences, practices and perceptions of a convenience sample of a small but diverse group of older adults in Cambodia.
METHOD: A cross-sectional qualitative study in which focus group interviews were conducted by 5 trained senior Cambodian dental students. A convenience sample of 56 older adults and caregivers was recruited across urban, semi-urban and rural locations. Focus group conversations were recorded, transcribed and analysed thematically.
RESULTS: The themes that emerged were around low expectations for both general health and oral health. A communal responsibility for health was expressed, and both money and transport were identified as key barriers to accessing care. Participants recognised that they had oral health problems, and acknowledged the impact of poor oral function on health and nutrition.
CONCLUSION: This study is an important first step in better understanding the oral health experiences and perceptions of older people in Cambodia. Participants described the impacts of poor oral health as being important, even when compared with other general health conditions.
A Red Flag: A Case of Oropharyngeal Cancer Masquerading as an Ulcer of an Infective Origin

Habib Rahman AF, Ahmad Fahmi AK, Ahmad Tarmizi NE, Hui Heng C, Mohan Singh AS

Cureus, 2023 Dec;15(12):e50411.
PMID: 38213374 DOI: 10.7759/cureus.50411

Oropharyngeal squamous cell carcinoma is a prevalent neoplastic condition. The incidence rate in Malaysia is rising, with human papillomavirus (HPV) infection being recognized as a significant contributing factor. Hence, it is paramount for physicians to effectively diagnose and identify significant indicators that may indicate a malignant etiology. In this study, we present a case of a middle-aged Malay male who presented with the primary symptom of persistent right throat discomfort for one month. The preliminary presentation, blood parameters, and initial histopathological examination (HPE) findings indicate the presence of an infection. However, despite undergoing several medical treatments, the patient's symptoms remain, albeit with only minor clinical improvement. Subsequently, the patient underwent a biopsy under general anesthesia, which subsequently yielded a report indicating the presence of oropharyngeal squamous cell carcinoma with a negative p16 status. Therefore, it is imperative for clinicians to possess knowledge of warning flags and exercise vigilance when encountering a patient who fails to respond despite thorough and precise evaluation. If there is a strong suspicion of malignancy, it is imperative to do a comprehensive clinical investigation and regular monitoring.