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A hybrid residue based sequential encoding mechanism with XGBoost improved ensemble model for identifying 5-hydroxymethylcytosine modifications

Uddin I, Awan HH, Khalid M, Khan S, Akbar S, Sarker MR, et al.

Sci Rep, 2024 Sep 06;14(1):20819.
PMID: 39242695 DOI: 10.1038/s41598-024-71568-z

RNA modifications play an important role in actively controlling recently created formation in cellular regulation mechanisms, which link them to gene expression and protein. The RNA modifications have numerous alterations, presenting broad glimpses of RNA's operations and character. The modification process by the TET enzyme oxidation is the crucial change associated with cytosine hydroxymethylation. The effect of CR is an alteration in specific biochemical ways of the organism, such as gene expression and epigenetic alterations. Traditional laboratory systems that identify 5-hydroxymethylcytosine (5hmC) samples are expensive and time-consuming compared to other methods. To address this challenge, the paper proposed XGB5hmC, a machine learning algorithm based on a robust gradient boosting algorithm (XGBoost), with different residue based formulation methods to identify 5hmC samples. Their results were amalgamated, and six different frequency residue based encoding features were fused to form a hybrid vector in order to enhance model discrimination capabilities. In addition, the proposed model incorporates SHAP (Shapley Additive Explanations) based feature selection to demonstrate model interpretability by highlighting the high contributory features. Among the applied machine learning algorithms, the XGBoost ensemble model using the tenfold cross-validation test achieved improved results than existing state-of-the-art models. Our model reported an accuracy of 89.97%, sensitivity of 87.78%, specificity of 94.45%, F1-score of 0.8934%, and MCC of 0.8764%. This study highlights the potential to provide valuable insights for enhancing medical assessment and treatment protocols, representing a significant advancement in RNA modification analysis.

Matched MeSH terms: Cytosine/analogs & derivatives; Cytosine/metabolism
From Nucleic Acids to Drug Discovery: Nucleobases as Emerging Templates for Drug Candidates

Wong XK, Yeong KY

Curr Med Chem, 2021 Oct 27;28(34):7076-7121.
PMID: 33588718 DOI: 10.2174/0929867328666210215113828

Nucleobases represent key structural motifs in biologically active molecules, including synthetic and natural products. Molecular modifications made on nucleobases or their isolation from natural sources are being widely investigated for the development of drugs with improved potency for the treatment of different diseases, such as cancer, as well as viral and bacterial infections. This review article focuses on the nucleobase analogue drug developments of the past 20 years (2000-2020). Various pharmacological and medicinal aspects of nucleobases and their analogues are discussed. The current state and limitations are also highlighted.

Matched MeSH terms: Cytosine
Cytosine methylation of rice mitochondrial DNA from grain and leaf tissues

Muniandy K, Tan MH, Shehnaz S, Song BK, Ayub Q, Rahman S

Planta, 2020 Feb 01;251(2):57.
PMID: 32008119 DOI: 10.1007/s00425-020-03349-7

MAIN CONCLUSION: The rice leaf mitochondrial DNA is more methylated compared to the rice grain mitochondrial DNA. The old rice leaf mitochondrial DNA has also a higher methylation level than the young rice leaf mitochondrial DNA. The presence of DNA methylation in rice organelles has not been well characterized. We have previously shown that cytosine methylation of chloroplast DNA is different between leaf and grain, and varies between young and old leaves in rice. However, the variation in cytosine methylation of mitochondrial DNA is still poorly characterized. In this study, we have investigated cytosine methylation of mitochondrial DNA in the rice grain and leaf. Based on CpG, CHG, and CHH methylation analyses, the leaf mitochondrial DNA was found to be more methylated compared to the grain mitochondrial DNA. The methylation of the leaf mitochondrial DNA was also higher in old compared to young leaves. Differences in methylation were observed at different cytosine positions of the mitochondrial DNA between grain and leaf, although there were also positions with a similar level of high methylation in all the tissues examined. The differentially methylated cytosine positions in rice mitochondrial DNA were observed mostly in the intergenic region and in some mitochondrial-specific genes involved in ATP production, transcription, and translation. The functional importance of cytosine methylation in the life cycle of rice mitochondria is still to be determined.

Matched MeSH terms: Cytosine/metabolism*
Graphite-Based Nanocomposite Electrochemical Sensor for Multiplex Detection of Adenine, Guanine, Thymine, and Cytosine: A Biomedical Prospect for Studying DNA Damage

Ng KL, Khor SM

Anal Chem, 2017 09 19;89(18):10004-10012.
PMID: 28845664 DOI: 10.1021/acs.analchem.7b02432

Guanine (G), adenine (A), thymine (T), and cytosine (C) are the four basic constituents of DNA. Studies on DNA composition have focused especially on DNA damage and genotoxicity. However, the development of a rapid, simple, and multiplex method for the simultaneous measurement of the four DNA bases remains a challenge. In this study, we describe a graphite-based nanocomposite electrode (Au-rGO/MWCNT/graphite) that uses a simple electro-co-deposition approach. We successfully applied the developed sensor for multiplex detection of G, A, T, and C, using square-wave voltammetry. The sensor was tested using real animal and plant DNA samples in which the hydrolysis of T and C could be achieved with 8 mol L-1 of acid. The electrochemical sensor exhibited excellent sensitivity (G = 178.8 nA/μg mL-1, A = 92.9 nA/μg mL-1, T = 1.4 nA/μg mL-1, and C = 15.1 9 nA/μg mL-1), low limit of detection (G, A = 0.5 μg mL-1; T, C = 1.0 μg mL-1), and high selectivity in the presence of common interfering factors from biological matrixes. The reliability of the established method was assessed by method validation and comparison with the ultraperformance liquid chromatography technique, and a correlation of 103.7% was achieved.

Matched MeSH terms: Cytosine/analysis*
Integrative analysis of chloroplast DNA methylation in a marine alga-Saccharina japonica

Teng L, Han W, Fan X, Zhang X, Xu D, Wang Y, et al.

Plant Mol Biol, 2021 Apr;105(6):611-623.
PMID: 33528753 DOI: 10.1007/s11103-020-01113-9

We applied an integrative approach using multiple methods to verify cytosine methylation in the chloroplast DNA of the multicellular brown alga Saccharina japonica. Cytosine DNA methylation is a heritable process which plays important roles in regulating development throughout the life cycle of an organism. Although methylation of nuclear DNA has been studied extensively, little is known about the state and role of DNA methylation in chloroplast genomes, especially in marine algae. Here, we have applied an integrated approach encompassing whole-genome bisulfite sequencing, methylated DNA immunoprecipitation, gene co-expression networks and photophysiological analyses to provide evidence for the role of chloroplast DNA methylation in a marine alga, the multicellular brown alga Saccharina japonica. Although the overall methylation level was relatively low in the chloroplast genome of S. japonica, gametophytes exhibited higher methylation levels than sporophytes. Gene-specific bisulfite-cloning sequencing provided additional evidence for the methylation of key photosynthetic genes. Many of them were highly expressed in sporophytes whereas genes involved in transcription, translation and biosynthesis were strongly expressed in gametophytes. Nucleus-encoded photosynthesis genes were co-expressed with their chloroplast-encoded counterparts potentially contributing to the higher photosynthetic performance in sporophytes compared to gametophytes where these co-expression networks were less pronounced. A nucleus-encoded DNA methyltransferase of the DNMT2 family is assumed to be responsible for the methylation of the chloroplast genome because it is predicted to possess a plastid transit peptide.

Matched MeSH terms: Cytosine/metabolism
Simultaneous electrochemical determination of DNA nucleobases using AgNPs embedded covalent organic framework

Arul P, Huang ST, Gowthaman NSK, Shankar S

Mikrochim Acta, 2021 Oct 01;188(10):358.
PMID: 34596766 DOI: 10.1007/s00604-021-05021-7

An efficient electrochemical biosensor has been developed for the simultaneous evaluation of DNA bases using AgNPs-embedded covalent organic framework (COF). The COF (p-Phenylenediamine and terephthalaldehyde) was synthesized by reflux (DMF; 150 °C; 12 h) and the nanoparticles were embedded from the aqueous solutions of AgNO3 and NaBH4. The nanocomposite-modified COF was confirmed by spectral, microscopic, and electrochemical techniques. The nanocomposite material was deposited on a glassy carbon electrode (GCE) and the redox behavior of AgNPs was confirmed by cyclic voltammetry. The electrocatalytic activities of DNA bases were analyzed by differential pulse voltammetry (DPV) in a physiological environment (PBS; pH = 7.0) based on simple and easy-to-use electrocatalyst. The AgNPs-COF/GCE showed well-defined anodic peak currents for the bases guanine (+ 0.63 V vs. Ag/AgCl), adenine (+ 0.89 V vs. Ag/AgCl), thymine (+ 1.10 V vs. Ag/AgCl), and cytosine (+ 1.26 V vs. Ag/AgCl) in a mixture as well as individuals with respect to the conventional, COF, and AgNPs/GCEs. The AgNPs-COF/GCE showed linear concentration range of DNA bases from 0.2-1000 µM (guanine; (G)), 0.1-500 µM (adenine (A)), 0.25-250 µM (thymine (T)) and 0.15-500 µM (cytosine (C)) and LOD of 0.043, 0.056, 0.062, and 0.051 µM (S/N = 3), respectively. The developed sensor showed reasonable selectivity, reproducibility (RSD = 1.53 ± 0.04%-2.58 ± 0.02% (n = 3)), and stability (RSD = 1.22 ± 0.06%-2.15 ± 0.04%; n = 3) over 5 days of storage) for DNA bases. Finally, AgNPs-COF/GCE was used for the determination of DNA bases in human blood serum, urine and saliva samples with good recoveries (98.60-99.11%, 97.80-99.21%, and 98.69-99.74%, respectively).

Matched MeSH terms: Cytosine/chemistry
Fulltext Human papillomavirus type 16 E7 oncoprotein mediates CCNA1 promoter methylation

Chalertpet K, Pakdeechaidan W, Patel V, Mutirangura A, Yanatatsaneejit P

Cancer Sci, 2015 Oct;106(10):1333-40.
PMID: 26250467 DOI: 10.1111/cas.12761

Human papillomavirus (HPV) oncoproteins drive distinctive promoter methylation patterns in cancer. However, the underlying mechanism remains to be elucidated. Cyclin A1 (CCNA1) promoter methylation is strongly associated with HPV-associated cancer. CCNA1 methylation is found in HPV-associated cervical cancers, as well as in head and neck squamous cell cancer. Numerous pieces of evidence suggest that E7 may drive CCNA1 methylation. First, the CCNA1 promoter is methylated in HPV-positive epithelial lesions after transformation. Second, the CCNA1 promoter is methylated at a high level when HPV is integrated into the human genome. Finally, E7 has been shown to interact with DNA methyltransferase 1 (Dnmt1). Here, we sought to determine the mechanism by which E7 increases methylation in cervical cancer by using CCNA1 as a gene model. We investigated whether E7 induces CCNA1 promoter methylation, resulting in the loss of expression. Using both E7 knockdown and overexpression approaches in SiHa and C33a cells, our data showed that CCNA1 promoter methylation decreases with a corresponding increase in expression in E7 siRNA-transfected cells. By contrast, CCNA1 promoter methylation was augmented with a corresponding reduction in expression in E7-overexpressing cells. To confirm whether the binding of the E7-Dnmt1 complex to the CCNA1 promoter induced methylation and loss of expression, ChIP assays were carried out in E7-, del CR3-E7 and vector control-overexpressing C33a cells. The data showed that E7 induced CCNA1 methylation by forming a complex with Dnmt1 at the CCNA1 promoter, resulting in the subsequent reduction of expression in cancers. It is interesting to further explore the genome-wide mechanism of E7 oncoprotein-mediated DNA methylation.
The relationship between single nucleotide polymorphisms of the interleukin-10 gene promoter in systemic lupus erythematosus patients in Malaysia: A pilot study

Hee CS, Gun SC, Naidu R, Somnath SD, Radhakrishnan AK

Int J Rheum Dis, 2008;11(2):148-154.
DOI: 10.1111/j.1756-185X.2008.00350.x

Aim: Recent studies have shown that single nucleotide polymorphisms (SNPs) have been identified within the promoter of the human interleukin-10 (IL-10) gene may participate in the pathogenesis of systemic lupus erythematosus (SLE) and may be related to disease activity. This is a pilot study that investigated the allelic and genotype frequencies of three SNPs in the human IL-10 gene promoter [rs1800896 (position: -1082G > A), rs1800871 (position: -824C > T) and rs1800872 (position: -597C > A)]among Malaysian SLE patients and normal subjects. Methods: Blood was drawn from 44 SLE patients and 44 age- and sex-matched healthy control subjects for DNA extraction. The SNPs were identified using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Results: There was no significant difference in the genotype and allele frequencies between the SLE patients and control subjects. A statistically significant difference was detected in the haplotype frequencies between the patients and controls (P = 0.004). Conclusions: There is a significant difference in the haplotype frequencies between the SLE patients and controls; the SNPs in the human IL-10 gene promoter could play an important role in the pathogenesis of SLE. © 2008 Asia Pacific League of Associations for Rheumatology and Blackwell Publishing Asia Pty Ltd.

Matched MeSH terms: Cytosine
On-Demand Ligand-Base DNA Sensor with Electrochemical Impedance Spectroscopy

Han H, Sabani NB, Nobusawa K, Takei F, Nakatani K, Yamashita I

Anal Chem, 2023 Jul 04;95(26):9729-9733.
PMID: 37341999 DOI: 10.1021/acs.analchem.3c01126

We have developed a DNA sensor that can be finalized to detect a specific target on demand. The electrode surface was modified with 2,7-diamino-1,8-naphthyridine (DANP), a small molecule with nanomolar affinity for the cytosine bulge structure. The electrode was immersed in a solution of synthetic probe-DNA that had a cytosine bulge structure at one end and a complementary sequence to the target DNA at the other end. The strong binding between the cytosine bulge and DANP anchored the probe DNAs to the electrode surface, and the electrode became ready for target DNA sensing. The complementary sequence portion of the probe DNA can be changed as requested, allowing for the detection of a wide variety of targets. Electrochemical impedance spectroscopy (EIS) with the modified electrode detected target DNAs with a high sensitivity. The charge transfer resistance (Rct) extracted from EIS showed a logarithmic relationship with the concentration of target DNA. The limit of detection (LoD) was less than 0.01 μM. By this method, highly sensitive DNA sensors for various target sequences could be easily produced.

Matched MeSH terms: Cytosine
Fulltext Epigenetic Control of the Vasopressin Promoter Explains Physiological Ability to Regulate Vasopressin Transcription in Dehydration and Salt Loading States in the Rat

Greenwood MP, Greenwood M, Gillard BT, Loh SY, Paton JF, Murphy D

J Neuroendocrinol, 2016 04;28(4).
PMID: 26833868 DOI: 10.1111/jne.12371

The synthesis of arginine vasopressin (AVP) in the supraoptic nucleus (SON) and paraventricular nucleus (PVN) of the hypothalamus is sensitive to increased plasma osmolality and a decreased blood volume, and thus is robustly increased by both dehydration (increased plasma osmolality and decreased blood volume) and salt loading (increased plasma osmolality). Both stimuli result in functional remodelling of the SON and PVN, a process referred to as functional-related plasticity. Such plastic changes in the brain have recently been associated with altered patterns of DNA methylation at CpG (cytosine-phosphate-guanine) residues, a process considered to be important for the regulation of gene transcription. In this regard, the proximal Avp promoter contains a number of CpG sites and is recognised as one of four CpG islands for the Avp gene, suggesting that methylation may be regulating Avp transcription. In the present study, we show that, in an immortalised hypothalamic cell line 4B, the proximal Avp promoter is highly methylated, and treatment of these cells with the DNA methyltransferase inhibitor 5-Aza-2'-deoxycytidine to demethylate DNA dramatically increases basal and stimulated Avp biosynthesis. We report no changes in the expression of DNA methyltransferases, Dnmt1 and Dnmt3a, whereas there is decreased expression of the demethylating enzyme ten-eleven-translocation 2, Tet2, in the SON by dehydration and salt loading. We found higher methylation of the SON Avp promoter in dehydrated but not salt-loaded rats. By analysis of individual CpG sites, we observed hypomethylation, hypermethylation and no change in methylation of specific CpGs in the SON Avp promoter of the dehydrated rat. Using reporter gene assays, we show that mutation of individual CpGs can result in altered Avp promoter activity. We propose that methylation of the SON Avp promoter is necessary to co-ordinate the duel inputs of increased plasma osmolality and decreased blood volume on Avp transcription in the chronically dehydrated rat.
Overexpression of DNA methyltransferase 1 (DNMT1) protein in astrocytic tumour and its correlation with O6-methylguanine-DNA methyltransferase (MGMT) expression

Rahman WF, Rahman KS, Nafi SN, Fauzi MH, Jaafar H

Int J Clin Exp Pathol, 2015;8(6):6095-106.
PMID: 26261487

The relationship between DNA methyltransferase (DNMT) and O6-methylguanine-DNA methyltransferase (MGMT) in mediating tumorigenesis is still poorly understood. This study was carried out to investigate a correlation between DNMT1 and MGMT immunoexpression in astrocytic tumour samples.
Fulltext A/T Run Geometry of B-form DNA Is Independent of Bound Methyl-CpG Binding Domain, Cytosine Methylation and Flanking Sequence

Chia JY, Tan WS, Ng CL, Hu NJ, Foo HL, Ho KL

Sci Rep, 2016 08 09;6:31210.
PMID: 27502833 DOI: 10.1038/srep31210

DNA methylation in a CpG context can be recognised by methyl-CpG binding protein 2 (MeCP2) via its methyl-CpG binding domain (MBD). An A/T run next to a methyl-CpG maximises the binding of MeCP2 to the methylated DNA. The A/T run characteristics are reported here with an X-ray structure of MBD A140V in complex with methylated DNA. The A/T run geometry was found to be strongly stabilised by a string of conserved water molecules regardless of its flanking nucleotide sequences, DNA methylation and bound MBD. New water molecules were found to stabilise the Rett syndrome-related E137, whose carboxylate group is salt bridged to R133. A structural comparison showed no difference between the wild type and MBD A140V. However, differential scanning calorimetry showed that the melting temperature of A140V constructs in complex with methylated DNA was reduced by ~7 °C, although circular dichroism showed no changes in the secondary structure content for A140V. A band shift analysis demonstrated that the larger fragment of MeCP2 (A140V) containing the transcriptional repression domain (TRD) destabilises the DNA binding. These results suggest that the solution structure of MBD A140V may differ from the wild-type MBD although no changes in the biochemical properties of X-ray A140V were observed.

Matched MeSH terms: Cytosine/chemistry*
Development of a modified method for sequencing high G:C regions in chicken anemia virus genome

Chowdhury SM, Omar AR, Aini I, Hair-Bejo M, Jamaluddin AA, Wan KL, et al.

J. Biochem. Mol. Biol. Biophys., 2002 Jun;6(3):229-32.
PMID: 12186760

Two areas in the chicken anemia virus (CAV) genome have high G:C content with secondary structures. These two G:C rich areas could not be sequenced with Perkin Elmer's Big Dye Terminator Cycle Sequencing Kit. Several modifications were carried out to solve the problem. Finally, a package of modified method was developed to sequence the high G:C areas. The result showed that the Perkin Elmer's Big Dye Terminator Cycle Sequencing Kit with the normal procedures are not suitable for sequencing the high G:C regions of the CAV genome. The present developed method made the Perkin Elmer's Kit useful for the first time to sequence the G:C rich hairpin structures of the CAV genome. The system may be useful to sequence all other G:C rich DNA templates.

Matched MeSH terms: Cytosine
Fulltext Penile warts: an update on their evaluation and management

Leung AK, Barankin B, Leong KF, Hon KL

Drugs Context, 2018;7:212563.
PMID: 30622585 DOI: 10.7573/dic.212563

Background: Penile warts are the most common sexually transmitted disease in males. Clinicians should be familiar with the proper evaluation and management of this common condition.
Objective: To provide an update on the current understanding, evaluation, and management of penile warts.
Methods: A PubMed search was completed in Clinical Queries using the key terms 'penile warts' and 'genital warts'. The search strategy included meta-analyses, randomized controlled trials, clinical trials, observational studies, and reviews.
Results: Penile warts are caused by human papillomavirus (HPV), notably HPV-6 and HPV-11. Penile warts typically present as asymptomatic papules or plaques. Lesions may be filiform, exophytic, papillomatous, verrucous, hyperkeratotic, cerebriform, fungating, or cauliflower-like. Approximately one-third of penile warts regress without treatment and the average duration prior to resolution is approximately 9 months. Active treatment is preferable to watchful observation to speed up clearance of the lesions and to assuage fears of transmission and autoinoculation. Patient-administered therapies include podofilox (0.5%) solution or gel, imiquimod 3.75 or 5% cream, and sinecatechins (polypheron E) 15% ointment. Clinician-administered therapies include podophyllin, cryotherapy, bichloroacetic or trichloroacetic acid, oral cimetidine, surgical excision, electrocautery, and carbon dioxide laser therapy. Patients who do not respond to first-line treatments may respond to other therapies or a combination of treatment modalities. Second-line therapies include topical/intralesional/intravenous cidofovir, topical 5-fluorouracil, and topical ingenol mebutate.
Conclusion: No single treatment has been shown to be consistently superior to other treatment modalities. The choice of the treatment method should depend on the physician's comfort level with the various treatment options, the patient's preference and tolerability of treatment, and the number and severity of lesions. The comparative efficacy, ease of administration, adverse effects, cost, and availability of the treatment modality should also be taken into consideration.

Matched MeSH terms: Cytosine
DNMT1 is associated with cell cycle and DNA replication gene sets in diffuse large B-cell lymphoma

Loo SK, Ab Hamid SS, Musa M, Wong KK

Pathol Res Pract, 2018 Jan;214(1):134-143.
PMID: 29137822 DOI: 10.1016/j.prp.2017.10.005

Dysregulation of DNA (cytosine-5)-methyltransferase 1 (DNMT1) is associated with the pathogenesis of various types of cancer. It has been previously shown that DNMT1 is frequently expressed in diffuse large B-cell lymphoma (DLBCL), however its functions remain to be elucidated in the disease. In this study, we gene expression profiled (GEP) shRNA targeting DNMT1(shDNMT1)-treated germinal center B-cell-like DLBCL (GCB-DLBCL)-derived cell line (i.e. HT) compared with non-silencing shRNA (control shRNA)-treated HT cells. Independent gene set enrichment analysis (GSEA) performed using GEPs of shRNA-treated HT cells and primary GCB-DLBCL cases derived from two publicly-available datasets (i.e. GSE10846 and GSE31312) produced three separate lists of enriched gene sets for each gene sets collection from Molecular Signatures Database (MSigDB). Subsequent Venn analysis identified 268, 145 and six consensus gene sets from analyzing gene sets in C2 collection (curated gene sets), C5 sub-collection [gene sets from gene ontology (GO) biological process ontology] and Hallmark collection, respectively to be enriched in positive correlation with DNMT1 expression profiles in shRNA-treated HT cells, GSE10846 and GSE31312 datasets [false discovery rate (FDR) <0.05]. Cell cycle progression and DNA replication were among the significantly enriched biological processes (FDR <0.05). Expression of genes involved in the activation of cell cycle and DNA replication (e.g. CDK1, CCNA2, E2F2, PCNA, RFC5 and POLD3) were highly correlated (r>0.8) with DNMT1 expression and significantly downregulated (log fold-change

Matched MeSH terms: Cytosine
Fulltext Molecular analysis of fragile X syndrome (FXS) among Malaysian patients with developmental disability

Ali EZ, Yakob Y, Md Desa N, Ishak T, Zakaria Z, Ngu LK, et al.

Malays J Pathol, 2017 08;39(2):99-106.
PMID: 28866690 MyJurnal

Fragile X syndrome (FXS) is a neurodevelopmental disorder commonly found worldwide, caused by the silencing of fragile X mental retardation 1 (FMR1) gene on the X-chromosome. Most of the patients lost FMR1 function due to an expansion of cytosine-guanine-guanine (CGG) repeat at the 5' untranslated region (5'UTR) of the gene. The purpose of this study is to identify the prevalence of FXS and characterize the FMR1 gene CGG repeats distribution among children with developmental disability in Malaysia. Genomic DNA of 2201 samples from different ethnicities (Malays, Chinese, Indian and others) of both genders were PCR-amplified from peripheral blood leukocytes based on specific primers at 5'UTR of FMR1 gene. Full mutations and mosaics were successfully identified by triple methylation specific PCR (ms-PCR) and subsequently verified with FragilEase kit. The findings revealed for the first time the prevalence of FXS full mutation in children with developmental disability in Malaysia was 3.5%, a slightly higher figure as compared to other countries. Molecular investigation also identified 0.2% and 0.4% probands have permutation and intermediate alleles, respectively. The CGG repeats length observation showed 95% of patients had normal alleles within 11 to 44 CGG repeats; with 29 repeats found most common among Malays and Indians while 28 repeats were most common among Chinese. In conclusion, this is the first report of prevalence and characterisation of CGG repeats that reflects genetic variability among Malaysian ethnic grouping.

Matched MeSH terms: Cytosine
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.

Matched MeSH terms: Cytosine
Fulltext Hb E beta +-thalassaemia in west Malaysia: clinical features in the most common beta-thalassaemia mutation of the Malays [IVS 1-5 (G-->C)]

George E, Wong HB

Singapore Med J, 1993 Dec;34(6):500-3.
PMID: 8153710

Patients with the Hb beta + [IVS 1-5 (G-->C)] clinically presented as beta-thalassaemia intermedia and remained asymptomatic in the absence of blood transfusions. With or without blood transfusions the patients were short and had moderate to marked thalassaemia facies. Children who received blood transfusions showed progressive iron loading with age. The serum ferritin and serum alanine transaminase levels were significantly raised in the patients who were given blood transfusions. In the presence of blood transfusions, and absence of adequate iron chelation therapy, splenectomy became an inevitable event at some stage of the disease because of increasing transfusing requirements.

Matched MeSH terms: Cytosine

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