Biomedical subjects

Ene-choo Tan

Publications and source records attributed to Ene-choo Tan.

4 recordsLinked to original sources

PubMed2006

Singapore Human Mutation/Polymorphism Database: a country-specific database for mutations and polymorphisms in inherited disorders and candidate gene association studies.

There is a need for country/population-specific databases because the existence of population-specific mutations for single gene disorders is well documented, and there is also good evidence for ethnic differences in the frequencies of genetic variations involved in complex disorders. Thus the Singapore Human Mutation/Polymorphism Database (SHMPD) was created to provide clinicians and scientists access to a central genetic database for the Singapore population. The data catalogued in the database include mutations identified in Singapore for Mendelian diseases, and frequencies of polymorphisms that have been investigated in either healthy controls or samples associated with specific phenotypes. Data from journal articles identified by searches in PubMed and other online resources, and via personal communications with researchers were compiled and assembled into a single database. Genes are categorized alphabetically and are also searchable by name and disease. The information provided for each variant of the gene includes the protein encoded, phenotype association, gender, size, and ethnic origin of the sample, as well as the reported genotype and allele frequencies, and direct links to the corresponding abstracts on PubMed. Our database will facilitate molecular diagnosis of Mendelian disorders and improve study designs for complex traits. It will be useful not only for researchers in Singapore, but also for those in countries with similar ethnic backgrounds, such as China, Taiwan, Hong Kong, Indonesia, and Malaysia.

Alleles↗

PubMed2006

Congenital long QT syndromes: clinical features, molecular genetics and genetic testing.

Congenital long QT syndrome (LQTS) is a primary electrical disease characterized by a prolonged QT interval in the surface electrocardiogram and increased predisposition to a typical polymorphic ventricular tachycardia, termed Torsade de Pointes. Most patients with LQTS are asymptomatic and are diagnosed incidentally based on an electrocardiogram. Symptomatic patients may suffer from severe cardiac events, such as syncope and/or sudden cardiac death. Autosomal dominant forms are caused by heterozygous mutations in genes encoding the components of the ion channels. The autosomal recessive form with congenital deafness is also known as Jervell and Lang-Nielsen syndrome. It is caused by homozygous mutations or certain compound heterozygous mutations. Depending on the genetic defects, there are differences in the age of onset, severity of symptoms, and number of cardiac events and event triggers. With advances in gene technology, it is now feasible to perform genetic testing for LQTS, especially for those with family history. Identification of the mutation will lead to better management of symptoms and more targeted treatment, depending on the underlying genetic defect, resulting in a reduction of mortality and cardiac events.

Ether-A-Go-Go Potassium Channels↗

PubMed2003

Case-control and linkage disequilibrium studies of the tryptophan hydroxylase gene polymorphisms and major depressive disorder.

OBJECTIVES: Alterations in the level of the serotonin, serotonin uptake and the number of binding sites have been linked to affective illness. We investigated the association of tryptophan hydroxylase gene polymorphisms and unipolar depression in a case-control study design. METHODS: Patients and ethnically matched controls were genotyped for three polymorphisms of the tryptophan hydroxylase gene. RESULTS Significant difference in genotype frequency between patient and control groups was observed for the IVS7+218A >C polymorphism but not for the two promoter polymorphisms -1067G >A and -347T >G. Strong linkage disequilibrium among the three polymorphisms was also observed. CONCLUSIONS: As the sample size was small, the positive association would need to be replicated by family-based association studies or in a larger set of samples. As our results did not indicate association with either of the two promoter polymorphisms, there is a need to continue the search for the causative variant directly involved in the susceptibility to unipolar depression in Chinese as this polymorphism within the intron might not be the true susceptibility variant.

Case-Control Studies↗

PubMed2002

Heterozygosities and allelic frequencies of a set of microsatellite markers used for genome-wide scans in a Chinese population.

Microsatellite (short tandem repeat) markers are useful tools for genetic linkage analysis because of their high frequency of occurrence in eukaryotic genomes, ease of typing, and high polymorphism content. To establish a panel of microsatellite markers useful for genome-wide screens in the Chinese population, we determined the heterozygosities and allelic frequencies of a widely used set of 285 markers in 208 individuals of Han Chinese descent. Although the median heterozygosity level in our Chinese population was 0.72, only 63.6% of these markers have a heterozygosity of at least 0.7, compared with 90.8% in the original Caucasian sample. The significant difference in heterozygosity and allelic frequencies between populations suggests that markers should be optimally selected for each study population to maximize information content and power.

China↗