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Interaction of Hb South Florida (codon 1; GTG-->ATG) and HbE, with beta-thalassemia (IVS1-1; G-->A): expression of different clinical phenotypes

Tan JA, Tan KL, Omar KZ, Chan LL, Wee YC, George E

Eur J Pediatr, 2009 Sep;168(9):1049-54.
PMID: 19034506 DOI: 10.1007/s00431-008-0877-9

INTRODUCTION: Interactions of different hemoglobin variants with thalassemia alleles can result in various clinical phenotypes. HbE-beta-thalassemia generally manifests with severe anemia where individuals exhibit beta-thalassemia major with regular blood transfusions or beta-thalassemia intermedia with periodic blood transfusions. This study presents a unique Malay family with three beta-globin gene defects-HbE, Hb South Florida, and IVS1-1 (G-->A).
MATERIALS AND METHODS: HbE activates a cryptic splice site that produces non-functional mRNAs. Hb South Florida is a rare beta-hemoglobin variant, and its interactions with other beta-thalassemia alleles have not been reported. IVS1-1 is a Mediterranean mutation that affects mRNA processing giving rise to beta(o)-thalassemia.
RESULTS AND DISCUSSION: Fifteen mutations along the beta-globin gene complex were analyzed using the amplification refractory mutation system. Hb South Florida was identified by direct sequencing using genomic DNA.
CONCLUSION: The affected child with HbE/IVS1-1 produced a beta-thalassemia major phenotype. Compound heterozygosity for Hb South Florida/IVS1-1 produced a beta-thalassemia carrier phenotype in the mother.
Characterisation and confirmation of rare beta-thalassaemia mutations in the Malay, Chinese and Indian ethnic groups in Malaysia

Tan JA, Chin PS, Wong YC, Tan KL, Chan LL, George E

Pathology, 2006 Oct;38(5):437-41.
PMID: 17008283

In Malaysia, about 4.5% of the Malay and Chinese populations are heterozygous carriers of beta-thalassaemia. The initial identification of rare beta-globin gene mutations by genomic sequencing will allow the development of simpler and cost-effective PCR-based techniques to complement the existing amplification refractory mutation system (ARMS) and gap-PCR used for the identification of beta-thalassaemia mutations.
Thalassemia intermedia in HbH-CS disease with compound heterozygosity for beta-thalassemia: challenges in hemoglobin analysis and clinical diagnosis

Tan JA, Kok JL, Tan KL, Wee YC, George E

Genes Genet Syst, 2009 Feb;84(1):67-71.
PMID: 19420802

Co-inheritance of alpha-thalassemia with homozygosity or compound heterozygosity for beta-thalassemia may ameliorate beta-thalassemia major. A wide range of clinical phenotypes is produced depending on the number of alpha-thalassemia alleles (-alpha/alphaalpha --/alphaalpha, --/-alpha). The co-inheritance of beta-thalassemia with alpha-thalassemia with a single gene deletion (-alpha/alphaalpha) is usually associated with thalassemia major. In contrast, the co-inheritance of beta-thalassemia with two alpha-genes deleted in cis or trans (--/alphaalpha or -alpha/-alpha) generally produces beta-thalassemia intermedia. In Southeast Asia, the most common defect responsible for alpha-thalassemia is the Southeast Asian (SEA) deletion of 20.5 kilobases. The presence of the SEA deletion with Hb Constant Spring (HbCS) produces HbH-CS disease. Co-inheritance of HbH-CS with compound heterozygosity for beta-thalassemia is very rare. This study presents a Malay patient with HbH-CS disorder and beta degrees/beta+-thalassemia. The SEA deletion was confirmed in the patient using a duplex-PCR. A Combine-Amplification Refractory Mutation System (C-ARMS) technique to simultaneously detect HbCS and Hb Quong Sze confirmed HbCS in the patient. Compound heterozygosity for CD41/42 and Poly A was confirmed using the ARMS. This is a unique case as the SEA alpha-gene deletion in cis (--SEA/alphaalpha) is generally not present in the Malays, who more commonly possess the two alpha-gene deletion in trans (-alpha/-alpha). In addition, the beta-globin gene mutation at CD41/42 is a common mutation in the Chinese and not in the Malays. The presence of both the SEA deletion and CD41/42 in the mother of the patient suggests the possible introduction of these two defects into the family by marriage with a Chinese.
Molecular defects in the beta-globin gene identified in different ethnic groups/populations during prenatal diagnosis for beta-thalassemia: a Malaysian experience

Tan JA, George E, Tan KL, Chow T, Tan PC, Hassan J, et al.

Clin Exp Med, 2004 Dec;4(3):142-7.
PMID: 15599663 DOI: 10.1007/s10238-004-0048-x

Beta-thalassemia is the most-common genetic disorder of hemoglobin synthesis in Malaysia, and about 4.5% of the population are heterozygous carriers of the disorder. Prenatal diagnosis was performed for 96 couples using the Amplification Refractory Mutation System and Gap-Polymerase Chain Reaction. We identified 17 beta-globin defects-initiation codon for translation (T-G), -29 (A-G), -28 (A-G), CAP +1 (A-C), CD 8/9 (+G), CD 15 (G-A), CD 17 (A-T), CD 19 (A-G), Hb E (G-A), IVS1-1 (G-T), IVS1-5 (G-C), CD 41/42 (-CTTT), CD 71-72 (+A), IVS2-654 (CT), poly A(A-G), 100-kb Ggamma(Agammadeltabeta) degrees and 45-kb Filipino deletions. The 192 beta-alleles studied comprised Chinese (151 patients), Malay (21), Orang Asli from East Malaysia (15), Filipino (1), Indian (1), Indonesian Chinese (2), and Thai (1). In the Chinese, 2 beta-globin defects at CD 41/42 and IVS2-654 were responsible for 74% of beta-thalassemia. beta-mutations at CD 19, IVS1-1 (G-T), IVS1-5, poly A, and hemoglobin E caused 76% of the hemoglobin disorders in the Malays. The Filipino 45-kb deletion caused 73.3% of bthalassemia in the Orang Asli. Using genomic sequencing, the rare Chinese beta-mutation at CD 43 (G-T) was confirmed in 2 Chinese, and the Mediterranean mutation IVS1-1 (G-A) was observed in a Malay beta-thalassemia carrier. The beta-globin mutations confirmed in this prenatal diagnosis study were heterogenous and 65 (68%) couples showed a different globin defect from each other. The use of specific molecular protocols has allowed rapid and successful prenatal diagnosis of beta-thalassemia in Malaysia.
Fulltext High prevalence of alpha- and beta-thalassemia in the Kadazandusuns in East Malaysia: challenges in providing effective health care for an indigenous group

Tan JA, Lee PC, Wee YC, Tan KL, Mahali NF, George E, et al.

J Biomed Biotechnol, 2010;2010.
PMID: 20871816 DOI: 10.1155/2010/706872

Thalassemia can lead to severe transfusion-dependent anemia, and it is the most common genetic disorder in Malaysia. This paper aims to determine the prevalence of thalassemia in the Kadazandusuns, the largest indigenous group in Sabah, East Malaysia. α- and β-thalassemia were confirmed in 33.6% and 12.8%, of the individuals studied respectively. The high prevalence of α- and β-thalassemia in the Kadazandusuns indicates that thalassemia screening, genetic counseling, and prenatal diagnosis should be included as part of their healthcare system. This preliminary paper serves as a baseline for further investigations into the health and genetic defects of the major indigenous population in Sabah, East Malaysia.
Iatrogenic tracheal flap mimicking tracheal stenosis with resultant stridor

Tan KL, Chong AW, Amin MA, Raman R

J Laryngol Otol, 2012 Jul;126(7):751-5.
PMID: 22578299 DOI: 10.1017/S0022215112000795

To illustrate a case of an iatrogenic mucosal tear in the trachea which caused a one-way valve effect, obstructing the airway and manifesting as post-extubation stridor.
Fulltext The prevalence and characteristics associated with mother-infant bed-sharing in Klang district, Malaysia

Tan KL, Ghani SN, Moy FM

Med J Malaysia, 2009 Dec;64(4):311-5.
PMID: 20954557 MyJurnal

This was a cross-sectional study to determine the prevalence and characteristics of mother-infant bed-sharing practice in Klang district, Malaysia. Data was collected by face-to-face interview using a structured questionnaire for a four month period in 2006. A total of 682 mother-infant pairs attending government health clinics were included in the study. Data regarding socio-demographic characteristics of the mothers, information on the infants, bed-sharing and breastfeeding practices were collected. The mean maternal age was 28.4 +/- 5.1 years while the mean infant gestational age was 38.8 +/- 1.8 weeks. The study showed the prevalence of bed-sharing was 73.5% (95% CI: 70.0, 76.7). In multivariate analysis; area of interview, maternal occupation, family income, breastfeeding and infant birth weight were associated with bed-sharing after adjusted for maternal ethnicity, age, marital status, educational level, parity, infant gender and infant gestational age. In conclusion, bed-sharing is a common practice in Klang district, Malaysia, not specific to ethnicity, but strongly associated with low family income and breastfeeding.
Fulltext Prevalence of onodi cells in Hospital Raja Permaisuri Bainun, Ipoh, Malaysia

Tan KL, Harvinder S

Med J Malaysia, 2010 Jun;65(2):101-2.
PMID: 23756790 MyJurnal

Onodi cell is a posterior ethmoid air cell that pneumatizes into the sphenoid sinus, It is an important entity for clinicians when performing endoscopic sinus surgery (EES) because it encroaches into the optic nerve and internal carotid artery. CT-scans are the road map for ESS to prevent damage to structures mentioned above. Its prevalence in Malaysia is unknown.
Fulltext Factors associated with exclusive breastfeeding among infants under six months of age in peninsular malaysia

Tan KL

Int Breastfeed J, 2011 Feb 02;6(1):2.
PMID: 21284889 DOI: 10.1186/1746-4358-6-2

BACKGROUND: Breastfeeding is accepted as the natural form of infant feeding. For mothers to be able to breastfeed exclusively to the recommended six months, it is important to understand the factors that influence exclusive breastfeeding. The aim of the study was to identify factors associated with exclusive breastfeeding in Peninsular Malaysia.
METHODS: This was a cross-sectional study involving 682 mother-infant pairs with infants up to six months attending maternal and child health section of the government health clinics in Klang, Malaysia. Data were collected by face-to-face interviews using a pre-tested structured questionnaire over 4 months in 2006. Data on breastfeeding were based on practice in the previous one month period. Logistic regression was used to assess the independent association between the independent variables and exclusive breastfeeding adjusting for infant age.
RESULTS: The prevalence of exclusive breastfeeding among mothers with infants aged between one and six months was 43.1% (95% CI: 39.4, 46.8). In the multivariate model exclusive breastfeeding was positively associated with rural residence, Malay mothers, non-working and non-smoking mothers, multiparous mothers, term infants, mothers with husbands who support breastfeeding and mothers who practice bed-sharing.
CONCLUSIONS: Interventions that seek to increase exclusive breastfeeding should focus on women who are at risk of early discontinuation of breastfeeding.
Bed sharing among mother-infant pairs in Klang district, Peninsular Malaysia and its relationship to breast-feeding

Tan KL

J Dev Behav Pediatr, 2009 Oct;30(5):420-5.
PMID: 19827222 DOI: 10.1097/DBP.0b013e3181ba083a

OBJECTIVE: The aim of the study was to determine the prevalence of mother-infant bed sharing in Klang district, Peninsular Malaysia and to identify factors associated with bed sharing.

METHOD: This was a cross-sectional study involving 682 mother-infant pairs with infants up to 6 months attending government clinics in Klang district, Peninsular Malaysia. Data were collected by face-to-face interview using a pretested structured questionnaire for a 4-month period in 2006. Data regarding maternal, paternal, obstetric, infant, occupancy, breast-feeding characteristics, and bed-sharing practice were collected. Data on bed sharing were based on practice in the past 1-month period. Bed sharing was defined as an infant sharing a bed with mother, and infant must be within arms reach from the mother, whereas a bed was defined as either a sleeping mattress placed on a bed frame or placed on the floor. The prevalence of bed sharing was estimated. Relationship and magnitude of association between independent factors and bed sharing were examined using odds ratio and 95% confidence interval. Logistic regression analysis was used to control for confounding factors.

RESULTS: The prevalence of bed sharing among mothers with infants aged between 1 and 6 months was 73.5% (95% confidence interval: 70.0-76.7). In multivariate analysis, urban/rural differences, mothers' ethnicity, occupation, family income, husbands' support on bed sharing, number of children younger than 12 years staying in the house, and breast-feeding were associated with bed sharing.

CONCLUSIONS: These factors need to be considered in analyzing the overall risks and benefits of bed sharing, paying attention to breastfeeding practices.
Fulltext Reassessment on the development of children with disability in Malaysia

Tan KL, Yadav H

Med J Malaysia, 2008 Mar;63(1):17-20.
PMID: 18935725 MyJurnal

This is a cohort study investigating the profile of children with disability registered with the primary health care clinics in Malaysia. The purpose of the study was to determine whether reassessment on the development of children with disability under rehabilitation should be done at three months interval or six months interval. Secondary data from the pilot project conducted by the Family Health Development Division, Ministry of Health Malaysia was used in this study. The study was carried out for seven months from 1st August 2004 until 28th February 2005. A total of 168 disabled children followed up for six months were selected in this study. Schedule of Growing Scale (SGS) II was the tool used for analysis. Results showed a statistically significant difference in the mean total SGS score at six months interval but not at three months interval. The result suggests that reassessment on children with Down Syndrome, Autism, Cerebral Palsy, mental retardation and delayed speech under rehabilitation should be carried out every six months while children with gross developmental delay and slow learner might need a longer interval for reassessment.
Fulltext Assessing the development of children with disability in Malaysia

Tan KL, Yadav H

Med J Malaysia, 2008 Aug;63(3):199-202.
PMID: 19248689 MyJurnal

This is a cross-sectional study investigating the profile of children with disability registered with the primary health care clinics in Malaysia. The purpose of the study was to assess the developmental stage of children with disability. Secondary data from the pilot project conducted by the Family Health Development Division, Ministry of Health Malaysia was used in this study. The study period was for six months from 1st August 2004 until 31st January 2005. A total of 900 disabled children were selected in this study. Schedule of Growing Scale (SGS) II was used for analysis. Results showed more boys than girls were affected with a ratio of 6:4. The mean total SGS score increases as the age of the child increased. The score was highest in delayed speech cases and lowest in cerebral palsy cases. The performance among children with delayed speech was the highest while children with cerebral palsy were the lowest. There was a statistically significant difference between the major ethnic groups in delayed speech and attention deficit hyperactive disorder.
Questionnaire: Denver Developmental Assessment Test II chart; DSST; Schedule of Growing Scale II; SGS
Fulltext Transcriptional profiling of the postnatal brain of the Ts1Cje mouse model of Down syndrome

Tan KL, Ling KH, Hewitt CA, Cheah PS, Simpson K, Gordon L, et al.

Genom Data, 2014 Dec;2:314-7.
PMID: 26484118 DOI: 10.1016/j.gdata.2014.09.009

The Ts1Cje mouse model of Down syndrome (DS) has partial trisomy of mouse chromosome 16 (MMU16), which is syntenic to human chromosome 21 (HSA21). It develops various neuropathological features demonstrated by DS patients such as reduced cerebellar volume [1] and altered hippocampus-dependent learning and memory [2,3]. To understand the global gene expression effect of the partially triplicated MMU16 segment on mouse brain development, we performed the spatiotemporal transcriptome analysis of Ts1Cje and disomic control cerebral cortex, cerebellum and hippocampus harvested at four developmental time-points: postnatal day (P)1, P15, P30 and P84. Here, we provide a detailed description of the experimental and analysis procedures of the microarray dataset, which has been deposited in the Gene Expression Omnibus (GSE49050) database.
Combine-ARMS: a rapid and cost-effective protocol for molecular characterization of beta-thalassemia in Malaysia

Tan KL, Tan JA, Wong YC, Wee YC, Thong MK, Yap SF

Genet. Test., 2001;5(1):17-22.
PMID: 11336396 DOI: 10.1089/109065701750168626

Beta-thalassemia major patients have chronic anemia and are dependent on blood transfusions to sustain life. Molecular characterization and prenatal diagnosis of beta3-thalassemia is essential in Malaysia because about 4.5% of the population are heterozygous carriers for beta-thalassemia. The high percentage of compound heterozygosity (47.62%) found in beta-thalassemia major patients in the Thalassaemia Registry, University of Malaya Medical Centre (UMMC), Malaysia, also supports a need for rapid, economical, and sensitive protocols for the detection of beta-thalassemia mutations. Molecular characterization of beta-thalassemia mutations in Malaysia is currently carried out using ARMS, which detects a single beta-thalassemia mutation per PCR reaction. We developed and evaluated Combine amplification refractory mutation system (C-ARMS) techniques for efficient molecular detection of two to three beta-thalassemia mutations in a single PCR reaction. Three C-ARMS protocols were evaluated and established for molecular characterization of common beta-thalassemia mutations in the Malay and Chinese ethnic groups in Malaysia. Two C-ARMS protocols (cd 41-42/IVSII #654 and -29/cd 71-72) detected the beta-thalassemia mutations in 74.98% of the Chinese patients studied. The CARMS for cd 41-42/IVSII #654 detected beta-thalassemia mutations in 72% of the Chinese families. C-ARMS for cd 41-42/IVSI #5/cd 17 allowed detection of beta-thalassemia mutations in 36.53% of beta-thalassemia in the Malay patients. C-ARMS for cd 41-42/IVSI #5/cd 17 detected beta-thalassemia in 45.54% of the Chinese patients. We conclude that C-ARMS with the ability to detect two to three mutations in a single reaction provides more rapid and cost-effective protocols for beta-thalassemia prenatal diagnosis and molecular analysis programs in Malaysia.
Transcutaneous bilirubinometry in fullterm Chinese and Malay infants

Tan KL

Acta Paediatr Scand, 1982 Jul;71(4):593-6.
PMID: 7136674
Perinatal mortality with particular reference to the Singapore situation

Tan KL

Ann Acad Med Singap, 1984 Apr;13(2):252-63.
PMID: 6497323

Perinatal mortality rates have been gradually declining in all countries. The initial decline mainly resulted from improvements in the late foetal mortality rates. Later with improvements in neonatal care, early neonatal mortality rates also improved. The developed countries have consistently shown better results than the developing countries, an indication of the higher standard of living, general health as well as the delivery of health care in these countries. In the Singapore situation, a rapid improvement in perinatal mortality was initially observed due to improvements in the late foetal mortality, followed later by reduction in the early neonatal mortality due to upgrading of neonatal intensive care. The perinatal mortality rate is lowest in the Chinese compared to the Indians and Malays, most likely due to the dietary practices of the three ethnic groups in Singapore; while the Chinese encourage extra nutrition in the pregnant female, the Malays and Indians tend to practise dietary restriction during this period. The improved nutrition of the pregnant mother is a factor in improving the perinatal mortality.
Perinatal mortality

Tan KL, Woon KY

J Singapore Paediatr Soc, 1979;Suppl:57-67.
PMID: 550004
Phototherapy for neonatal jaundice in Chinese, Malay and Indian infants

Tan KL

Aust Paediatr J, 1976 Mar;12(1):43-6.
PMID: 962730
Neonatal jaundice in premature infants

Tan KL

J Singapore Paediatr Soc, 1977 Dec;19(4):238-40.
PMID: 616476
Fulltext Factors Associated with Non-exclusive Breastfeeding among 4-Week Post-partum Mothers in Klang District, Peninsular Malaysia

Tan KL

Malays J Nutr, 2009 Mar;15(1):11-8.
PMID: 22691800 MyJurnal

This is a cross-sectional study which investigated the association between non-exclusive breastfeeding and maternal, paternal, obstetric and infant factors. Data on maternal, paternal, obstetric and infant factors were collected through face-to-face interview using a structured questionnaire from 498 mothers with four-week-old infants who attended government clinics in Klang district between 17 and 28 July 2006. The prevalence of non-exclusive breastfeeding at four weeks was 45.8%. Factors significantly associated with non-exclusive breastfeeding at four weeks included Indian ethnic mother (OR = 4.06), working mother (OR = 3.55), mother from high household income (OR = 1.90), mother who smokes (OR = 7.27), primiparous (OR = 1.97), infant not sharing a bed with mother (OR = 1.75) and infant born prematurely (OR = 7.69). Identification of risk factors should assist in targeting women who are at increased risk of non-exclusive breastfeeding.

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