Germline mutations of 4567 patients with hereditary breast-ovarian cancer spectrum in Thailand.

Multi-gene panel testing has led to the detection of pathogenic/likely pathogenic (P/LP) variants in many cancer susceptibility genes in patients with breast-ovarian cancer spectrum. However, the clinical and genomic data of Asian populations, including Thai cancer patients, was underrepresented, and the clinical significance of multi-gene panel testing in Thailand remains undetermined. In this study, we collected the clinical and genetic data from 4567 Thai patients with cancer in the hereditary breast-ovarian cancer (HBOC) spectrum who underwent multi-gene panel testing. Six hundred and ten individuals (13.4%) had germline P/LP variants. Detection rates of germline P/LP variants in breast, ovarian, pancreatic, and prostate cancer were 11.8%, 19.8%, 14.0%, and 7.1%, respectively. Non-BRCA gene mutations accounted for 35% of patients with germline P/LP variants. ATM was the most common non-BRCA gene mutation. Four hundred and thirty-two breast cancer patients with germline P/LP variants (80.4%) met the current NCCN genetic testing criteria. The most common indication was early-onset breast cancer. Ten patients harbored double pathogenic variants in this cohort. Our result showed that a significant proportion of non-BRCA P/LP variants were identified in patients with HBOC-related cancers. These findings support the benefit of multi-gene panel testing for inherited cancer susceptibility among Thai HBOC patients. Some modifications of the testing policy may be appropriate for implementation in diverse populations.

STK11 Causative Variants and Copy Number Variations Identified in Thai Patients With Peutz-Jeghers Syndrome.

Introduction Peutz-Jeghers syndrome (PJS) is a rare autosomal dominant inherited disorder caused by germline mutations in the serine-threonine kinase 11 (STK11) tumor suppressor gene. This syndrome is characterized by hamartomatous gastrointestinal polyps, mucocutaneous melanin pigmentation, and a higher risk of developing various cancers. Methods We summarized the clinical and molecular characteristics of five unrelated Thai patients with PJS. Denaturing high-performance liquid chromatography (DHPLC) screening, coupled with direct DNA sequencing and multiplex ligation-dependent probe amplification (MLPA), were applied for the molecular analysis of STK11. Results A total of four STK11 pathogenic changeswere identified in the five PJS patients, including two frameshift variants (a novel c.199dup, p.Leu67ProfsTer96 and a known c.834_835del, p.Cys278TrpfsTer6) and two types of copy number variations (CNV), exon 1 deletion and exons 2-3 deletion. Among reported STK11 exonic deletions, exon 1 and exons 2-3 deletions were found to be the two most commonly deleted exons. Conclusion All identified STK11 mutations were null mutations that were associated with more severe PJS phenotypes and cancers. This study broadens the phenotypic and mutational spectrum of STK11 in PJS.

The efficacy of low-dose warfarin initiation (3 mg versus 5 mg) in newly diagnosed venous thromboembolism patients among a population with a high prevalence of warfarin-sensitive haplotype of the VKORC1 gene: a randomized controlled trial.

OBJECTIVES: The fact that a lower warfarin maintenance dose is required by Asian populations is well-known. Currently, the American College of Chest Physicians recommends commencing warfarin at a dose between 5 and 10 mg for venous thromboembolism (VTE). However, the optimal initiating dose in Asians is unknown. This study aimed to evaluate the efficacy of a 3 mg versus a 5 mg of warfarin initiating dose and a corresponding nomogram in patients with VTE. METHODS: Eligible patients were randomized to receive 3 mg or 5 mg per day warfarin for the first 2 days of treatment. The subsequent dose was adjusted according to the warfarin nomogram. The primary outcome was the number of patients who achieved an INR 2.0-3.0 within 8 days. RESULTS: Fifty-six patients were enrolled. There was no significant difference in baseline characteristics between the groups. Seventeen (60.7%) patients in the 3-mg group and 22 (78.6%) patients in the 5-mg group achieved a therapeutic INR within 8 days (p = 0.146). However, there were significantly more patients in the 5-mg group who achieved the target INR on day 5 (53.6% vs 25.0%, p = 0.029). Furthermore, VKORC1-1639G > A was associated with an increased likelihood to achieve the target INR within 5 days (OR 3.81, 95%CI 1.19-12.16, p = 0.021). CONCLUSIONS: The efficacy of a 3 mg warfarin starting dose with subsequent dose adjustment was similar to that of 5 mg on day 8 after warfarin initiation. However, a 5 mg initiating dose resulted in more patients who achieved therapeutic INR on day 5.

Effect of gene polymorphisms in ADAM33, TGFß1, VEGFA, and PLAUR on asthma in Thai population.

BACKGROUND: Most of the asthma susceptibility genes have demonstrated moderate effect. Gene-gene interaction may play a role in asthma. OBJECTIVE: To investigate the genetic and gene-gene interaction effects of single nucleotide polymorphisms (SNPs) in the ADAM33, TGFß1, VEGFA, and PLAUR genes on asthma in Thai population. METHODS: Two hundred and fifty control and 250 asthmatic Thai subjects were recruited. Asthma was diagnosed based on symptoms and spirometry assessments using criteria outlined by the American Thoracic Society. Degrees of asthma severity were determined according to guidelines provided by the Global Initiative for Asthma. Asthmatic subjects were subcategorized into the low-severity (n = 106) and high-severity (n = 144) groups. Eleven SNPs in four genes were genotyped, including ADAM33 SNPs (rs528557/S2, rs598418, rs44707/ST+4), TGFß1 SNPs (rs2241715, rs11466345), VEGFA SNPs (rs833069, rs3025010), and PLAUR SNPs (rs344781, rs344787, rs2239374, rs2239372). Association analyses between SNPs and asthma, and tests for gene-gene interaction were performed. RESULTS: The ADAM33 rs528557/S2 SNP was found to be associated with asthma according to the additive and dominant models. Comparison between the low-severity group and controls showed the VEGFA rs833069 SNP to be significantly associated with the low-severity group. No gene-gene interactions were observed in this study. CONCLUSIONS: The ADAM33 rs528557/S2 and the VEGFA rs833069 SNPs were associated with Thai asthmatics, as well as with other populations worldwide. Further studies are warranted to investigate the use these SNPs as biomarkers for establishing early diagnosis or for predicting future risk of asthma.

Thai patients who fulfilled NCCN criteria for breast/ovarian cancer genetic assessment demonstrated high prevalence of germline mutations in cancer susceptibility genes: implication to Asian population testing.

BACKGROUND: Germline genetic mutation plays a significant role in breast cancer susceptibility. The strength of such predisposition varies among ethnic groups across the globe, and clinical data from Asian population to develop a strategic approach to who should undergo a genetic test are lacking. METHODS: We performed a multigene test with next generation sequencing in Thai patients whose clinical history fulfilled NCCN criteria for breast/ovarian cancer genetic assessment, consists of 306 breast cancer patients, 62 ovarian cancer patients, 14 pancreatic cancer patients and 7 prostate cancer patients. Genetic test result and clinical history were then checked with each NCCN criteria to determined detection rate for each indication. RESULTS: There were 83 pathogenic/likely pathogenic (P/LP) variants identified in 104 patients, 44 of these P/LP variants were novel. We reported a high rate of germline P/LP variants in breast cancer (24%), ovarian cancer (37%), pancreatic cancer (14%), and prostate cancer (29%). Germline P/LP variants in BRCA1 and BRCA2 accounted for 80% of P/LP variants found in breast cancer and 57% of P/LP variants found in ovarian cancer. The detection rate of patients who fulfilled NCCN 2019 guideline for genetic/familial high-risk assessment of breast and ovarian cancers was 22-40%. CONCLUSION: Overall, the data from this study strongly support the consideration of multigene panel test as a diagnostic tool for patients with inherited cancer susceptibility in Thailand and Asian population. Implementation of the NCCN guideline is applicable, some modification may be needed to be more suitable for Asian population.

Molecular and clinical characterization of Thai patients with achromatopsia: identification of three novel disease-associated variants in the CNGA3 and CNGB3 genes.

PURPOSE: Achromatopsia (ACHM) is an autosomal recessive cone disorder characterized by pendular nystagmus, photophobia, reduced visual acuity, and partial or total absence of color vision. Mutations in six genes (CNGA3, CNGB3, GNAT2, PDE6C, PDE6H, and ATF6) have been reported in ACHM. There is no information on these disease-associated genes in Thai population. This study aimed to investigate the molecular and clinical characteristics in Thai patients with ACHM. METHODS: Seven unrelated Thai patients with ACHM were recruited. Detailed ophthalmologic examination was performed. Polymerase chain reaction (PCR)-coupled single-strand conformation polymorphism (SSCP) screening followed by Sanger sequencing was used to identify sequence variants in all exons and splice junctions of three genes (CNGA3, CNGB3, and GNAT2). The pathogenicity of the detected variants was interpreted. Segregation analysis was performed to determine variant sharing in available family members. RESULTS: Four patients displayed different SSCP migration patterns. Sequence analysis revealed a reported pathogenic and a novel disease-associated variant in the CNGA3 gene. For the CNGB3 gene, we found two novel disease-associated variants and a reported variant of uncertain significance (VUS). Segregation analysis confirmed that the variants identified in each patient were present in the heterozygous state in their corresponding family members, which was consistent with an autosomal recessive mode of inheritance. CONCLUSIONS: This study demonstrated the first molecular and clinical characterization of ACHM in Thai patients. The identification of disease-associated genes in a specific population leads to a personalized gene therapy benefiting those affected patients.

High Frequency of KRAS Codon 146 and FBXW7 Mutations in Thai Patients with Stage II-III Colon Cancer.

Background: KRAS, NRAS, and BRAF gene mutations are the most clinically relevant and frequently reported in colorectal cancer (CRC). Although data on these genes are frequently reported in several counties, data specific to these genes among Thai population are scarce. The aim of this study was to investigate and identify molecular alterations associated with colon cancer in Thai population, and to determine the impact of these genetic aberrations on clinical outcome. Methods: DNA from 108 archived formalin-fixed, paraffin-embedded (FFPE) tissue samples that histologically confirmed adenocarcinoma of stage II-III colon cancer between 2010 and 2012 at Siriraj Hospital (Bangkok, Thailand) were extracted. Gene mutational analysis was performed by next-generation sequencing (NGS) using an Oncomine Solid Tumor DNA kit (Thermo Fisher Scientific, Inc., Waltham, MA, USA). Results: A total of 22 somatic gene mutations were detected. The mutation frequency observed in KRAS, NRAS, BRAF, PIK3CA, and FBXW7 mutations was 47.2%, 1.9%, 1.9%, 12%, and 14.8%, respectively. KRAS mutation codon 12, 13, 59, 61, 117, and 146 mutations were identified in 29.6%, 8.3%, 1.8%, 0.9%, 0.0%, and 8.3%, respectively. KRAS Exon 4 had better DFS compared with Exon 2 and 3. Conclusions: This study is the first to comprehensively report hotspot mutations using NGS in Thai colon cancer patients. The most commonly identified gene mutation frequencies among Thai patients (KRAS, NRAS, BRAF, TP53, and PIK3CA) were similar to the gene mutation frequencies reported in Western population, except for subgroup of KRAS codon 146 and FBXW7 mutations that had a slightly higher frequency.

Tumor mutational profile of triple negative breast cancer patients in Thailand revealed distinctive genetic alteration in chromatin remodeling gene.

BACKGROUND: Triple negative breast cancer (TNBC) is a breast cancer subtype characterized by absence of both hormonal receptors and human epithelial growth factor receptor 2 (HER2). TNBC accounts for 15-20% of breast cancer. TNBC is associated with more aggressive disease and worse clinical outcome. Though the underlying mechanism of TNBC is currently unclear, the heterogeneity of clinical characteristics in various population may relate to the difference in tumor mutational profile. There were studies on TNBC gene mutations in various ethnic groups but the tumor genome data on Thai TNBC patients is currently unknown. This study aims to investigate mutational profile of Thai TNBC. METHODS: The patients were Thai individuals who were diagnosed with primary breast carcinoma between 2014 and 2017. All surgically removed primary tumor tissues were carefully examined by pathologists and archived as formalin-fixed paraffin-embedded tumor. TNBC was defined by absence of hormonal receptors and HER2 by immunohistochemistry. Genomic DNA was extracted, enriched and sequenced of all exomes on the Illumina HiSeq. Genomic data were then processed through bioinformatics platform to identify genomic alterations and tumor mutational burden. RESULTS: A total of 116 TNBC patients were recruited. Genomic analysis of TNBC samples identified 81,460 variants, of which 5,906 variants were in cancer-associated genes. The result showed that Thai TNBC has higher tumor mutation burden than previously reported data. The most frequently mutated cancer-associated gene was TP53 similar to other TNBC cohorts. Meanwhile KMT2C was found to be more commonly mutated in Thai TNBC than previous studies. Mutational profile of Thai TNBC patients also revealed difference in many frequently mutated genes when compared to other Western TNBC cohorts. CONCLUSION: This result supported that TNBC breast cancer patients from various ethnic background showed diverse genome alteration pattern. Although TP53 is the most commonly mutated gene across all cohorts, Thai TNBC showed different gene mutation frequencies, especially in KMT2C. In particular, the cancer gene mutations are more prevalent in Thai TNBC patients. This result provides important insight on diverse underlying genetic and epigenetic mechanisms of TNBC that could translate to a new treatment strategy for patients with this disease.

Molecular investigation by whole exome sequencing revealed a high proportion of pathogenic variants among Thai victims of sudden unexpected death syndrome.

INTRODUCTION: Sudden unexpected death syndrome (SUDS) is an important cause of death in young healthy adults with a high incident rate in Southeast Asia; however, there are no molecular autopsy reports about these victims. We performed a combination of both a detailed autopsy and a molecular autopsy by whole exome sequencing (WES) to investigate the cause of SUDS in Thai sudden death victims. MATERIALS AND METHODS: A detailed forensic autopsy was performed to identify the cause of death, followed by a molecular autopsy, in 42 sudden death victims who died between January 2015 and August 2015. The coding sequences of 98 SUDS-related genes were sequenced using WES. Potentially causative variants were filtered based on the variant functions annotated in the dbNSFP database. Variants with inconclusive clinical significance evidence in ClinVar were resolved with a variant prediction algorithm, metaSVM, and the frequency data of the variants found in public databases, such as the 1000 Genome Project, ESP6500 project, and the Exome Aggregation Consortium (ExAc) project. RESULTS: Combining both autopsy and molecular autopsy enabled the potential identification of cause of death in 81% of the cases. Among the 25 victims with WES data, 72% (18/25) were found to have potentially causative SUDS mutations. The majority of the victims had at a mutation in the TTN gene (8/18 = 44%), and only one victim had an SCN5A mutation. CONCLUSIONS: WES can help to identify the genetic causes in victims of SUDS and may help to further guide investigations into their relatives to prevent additional SUDS victims.

Whole Exome Sequencing in Eight Thai Patients With Leber Congenital Amaurosis Reveals Mutations in the CTNNA1 and CYP4V2 Genes.

Purpose: Our goal was to describe the clinical and molecular genetic findings in Thai patients with Leber congenital amaurosis (LCA). Methods: Whole exome sequencing (WES) was performed in eight unrelated patients. All genes responsible for inherited retinal diseases (IRDs) based on RetNet were selected for analysis. Potentially causative variants were filtered through a bioinformatics pipeline and validated using Sanger sequencing. Segregation analysis of the causative genes was performed in family members when available. Results: Eleven deleterious variants, six nonsense and five missense, were identified in seven genes: four LCA-associated genes (CEP290, IQCB1, NMNAT1, and RPGRIP1), one gene responsible for syndromic LCA (ALMS1), and two IRDs-related genes (CTNNA1 and CYP4V2). Clinical reassessment supported the diagnosis of syndromic LCA in those patients harboring potentially pathogenic variants in the ALMS1. Interestingly, two causative genes, CTNNA1 and CYP4V2, previously reported to cause butterfly-shaped pigment dystrophy (BSPD) and Bietti's crystalline dystrophy (BCD), respectively, were detected in two other patients. These two patients developed rapid and severe visual loss in contrast to BSPD and BCD patients in previous studies. The results of this study demonstrate that causative variants identified in the CTNNA1 and CYP4V2 genes are also associated with LCA. Conclusions: This is the first report describing the molecular genetics and clinical manifestations of Thai patients with LCA. The present study expands the spectrum of LCA-associated genes, which is a benefit for molecular diagnosis. The identification of mutations in the CTNNA1 and CYP4V2 genes requires further elucidation in larger cohorts with LCA.

A novel start codon mutation of the MERTK gene in a patient with retinitis pigmentosa.

PURPOSE: Retinitis pigmentosa (RP) is a clinically and genetically heterogeneous group of inherited retinal degenerations characterized by progressive loss of photoreceptor cells and RPE functions. More than 70 causative genes are known to be responsible for RP. This study aimed to identify the causative gene in a patient from a consanguineous family with childhood-onset severe retinal dystrophy. METHODS: To identify the defective gene, whole exome sequencing was performed. Candidate causative variants were selected and validated using Sanger sequencing. Segregation analysis of the causative gene was performed in additional family members. To verify that the mutation has an effect on protein synthesis, an expression vector containing the first ten amino acids of the mutant protein fused with the DsRed2 fluorescent protein was constructed and transfected into HEK293T cells. Expression of the fusion protein in the transfected cells was measured using fluorescence microscopy. RESULTS: By filtering against public variant databases, a novel homozygous missense mutation (c.3G>A) localized in the start codon of the MERTK gene was detected as a potentially pathogenic mutation for autosomal recessive RP. The c.3G>A mutation cosegregated with the disease phenotype in the family. No expression of the first ten amino acids of the MerTK mutant fused with the DsRed2 fluorescent protein was detected in HEK293T cells, indicating that the mutation affects the translation initiation site of the gene that may lead to loss of function of the MerTK signaling pathway. CONCLUSIONS: We report a novel missense mutation (c.3G>A, p.0?) in the MERTK gene that causes severe vision impairment in a patient. Taken together with previous reports, our results expand the spectrum of MERTK mutations and extend our understanding of the role of the MerTK protein in the pathogenesis of retinitis pigmentosa.

Detection of CAPN10 copy number variation in Thai patients with type 2 diabetes by denaturing high performance liquid chromatography and real-time quantitative polymerase chain reaction.

AIMS/INTRODUCTION: A combination of multiple genetic and environmental factors contribute to the pathogenesis of type 2 diabetes. Copy number variations (CNVs) are associated with complex human diseases. However, CNVs can cause genotype deviation from the Hardy-Weinberg equilibrium (HWE). A genetic case-control association study in 216 Thai diabetic patients and 192 non-diabetic controls found that, after excluding genotyping errors, genotype distribution of calpain 10 (CAPN10) SNP44 (rs2975760) deviated from HWE. Here, we aimed to detect CNV within the CAPN10 SNP44 region. MATERIALS AND METHODS: CNV within the CAPN10 SNP44 region was detected using denaturing high-performance liquid chromatography, and the results confirmed by real-time quantitative polymerase chain reaction with SYBR Green I. RESULTS: Both methods successfully identified CNV in the CAPN10 SNP44 region, obtaining concordant results. Correction of genotype calling based on the status of identified CNVs showed that the CAPN10 SNP44 genotype is in good agreement with HWE (P > 0.05). However, no association between CNV genotypes and risk of type 2 diabetes was observed. CONCLUSIONS: Identified CNVs for CAPN10 SNP44 genotypes lead to deviation from HWE. Furthermore, both denaturing high-performance liquid chromatography and real-time quantitative polymerase chain reaction are useful for detecting CNVs.

Novel Mutation of the TINF2 Gene in a Patient with Dyskeratosis Congenita.

Dyskeratosis congenita (DKC) is a rare inherited disease that is characterized by abnormal skin pigmentation, nail dystrophy and mucosal leukoplakia. DKC is caused by an abnormality in a component of the telomerase and shelterin complexes. TINF2 encodes a protein in the shelterin complex and TERC encodes a component of the telomerase complex. Mutations of both genes have been associated with DKC. This study examined mutations in TINF2.

Circulating thyrotropin receptor messenger ribonucleic acid is not an effective marker in the follow-up of differentiated thyroid carcinoma.

BACKGROUND: Circulating thyrotropin receptor messenger ribonucleic acid (TSHR mRNA) assay has been validated in the follow-up of differentiated thyroid carcinoma (DTC) because of its high sensitivity during thyroid hormone therapy and no interference with endogenous anti-thyroglobulin antibodies (TgAb) compared to serum thyroglobulin (Tg). We investigated the efficacy of TSHR mRNA assay in 160 DTC patients using quantitative PCR (qPCR). FINDINGS: Only TSHR mRNA level of structural persistent disease with TgAb-positive (3.47 (2.97-9.53) pg equivalents/µg total RNA; p = 0.013) and its subgroup of distant metastasis patients with TgAb-positive (5.55 (3.28-12.52) pg equivalents/µg total RNA; p = 0.009) were significantly different from patients with no evidence of disease (2.32 (1.44-3.94) pg equivalents/µg total RNA). Applying cutoff at 2.00 pg equivalents/µg total RNA enabled us to predict structural persistent disease patients with a sensitivity of 62.3 % and a specificity of 42.9 %. Although, the sensitivity of TSHR mRNA assay in TgAb-postive patients (88.2 %) was superior than serum Tg (47.1 %) (p = 0.00002), the accuracy of the test is only 54.5 %. CONCLUSIONS: This study demonstrated that TSHR mRNA assay has good sensitivity in TgAb-positive patients but it is neither specific enough as a first-line of testing nor a surrogate marker in the follow-up of our DTC patients.

No association between CYP17 -34T/C polymorphism and insulin resistance in Thai polycystic ovary syndrome.

AIM: To investigate the association of CYP 17 -34T/C polymorphism with insulin resistance (IR) in Thai polycystic ovary syndrome (PCOS). METHODS: A cross-sectional study was performed on 210 Thai women diagnosed with PCOS. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to analyze CYP17 polymorphism at -34T/C. Student's t-test was used to compare the mean of normally distributed variables between A1/A1 and A2/X. Chi-squared or Fisher's exact tests and OR were used to analyze the association at P < 0.05. RESULTS: Out of 210 cases, PCR-RFLP was successful in 199. Mean patient age was 24.4 ± 4.7 years, with body mass index 25.2 ± 6.3 kg/m(2) . There were 65 and 134 women in the A1/A1 genotype group and A2/X genotype group, respectively. The A2/X genotype group was statistically significantly younger and had a strong trend toward overweight/obesity compared with the A1/A1 genotype group. The prevalence of IR according to different methods varied from 15.4% to 70.8% and was not different between the two groups. On subgroup analysis, in the overweight/obese PCOS group, the A2/X genotype was not associated with any indices of IR. CONCLUSION: No significant association between CYP17-34T/C polymorphism and IR was found in Thai PCOS women, although the A2/X genotype group was statistically significantly younger than the A1/A1 genotype group.

HLA-DRB1 and HLA-DQB1 Are Associated with Adult-Onset Immunodeficiency with Acquired Anti-Interferon-Gamma Autoantibodies.

Recently a newly identified clinical syndrome of disseminated non-tuberculous mycobacterial diseases (with or without other opportunistic infections in adult patients who were previously healthy, has been recognized in association with an acquired autoantibody to interferon-gamma. This syndrome is emerging as an important cause of morbidity and mortality, especially among people of Asian descent. Trigger for the production of this autoantibody remains unknown, but genetic factors are strongly suspected to be involved. We compared HLA genotyping between 32 patients with this clinical syndrome, and 38 controls. We found that this clinical syndrome was associated with very limited allele polymorphism, with HLA-DRB1 and DQB1 alleles, especially HLA-DRB1*15:01, DRB1*16:02, DQB1*05:01 and DQB1*05:02. Odds ratio of DRB1*15:01, DRB1*16:02, DQB1*05:01 and DQB1*05:02 were 7.03 (95% CI, 2.18-22.69, P<0.0001, 9.06 (95% CI, 2.79-29.46, P<0.0001), 6.68 (95% CI, 2.29-19.52, P = 0.0004), and 6.64 (95% CI, 2.30-19.20, P = 0.0004), respectively. Further investigation is warranted to provide better understanding on pathogenesis of this association.

Acquired somatic mutations of isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2) in preleukemic disorders.

Mutations of isocitrate dehydrogenase isoform 1 and 2 (IDH1 and IDH2) genes have been identified in glioblastoma and acute myeloid leukemia (AML). However, little is known about the molecular alterations of IDH genes in preleukemic disorders with a propensity to transform to AML. We performed polymerase chain reaction-denaturing high performance liquid chromatography (PCR-DHPLC) followed by direct sequencing to detect IDH mutations in 237 patients with myeloproliferative neoplasms (MPNs; n=108), myelodysplastic syndrome (MDS; n=22), paroxysmal nocturnal hemoglobinuria (PNH; n=41), and aplastic anemia (AA; n=66). No IDH1 R132 and IDH2 R172 mutations were identified in the entire cohort, whereas IDH1 G105G allele was detected in 4/108 MPN (3.70%), 2/22 MDS (9.09%), and 2/41 PNH (4.88%) patients. Three IDH2 R140Q mutations were found in 2/108 MPN (1.85%) and 1/22 MDS (4.54%) patients, while one IDH2 G145G allele was found in 0.92% (1/108) of MPN patients. Overall, our data suggest that IDH mutations are rare in the preleukemic disorders and may not be the major initial step in AML leukemogenesis.

Mycophenolic acid AUC in Thai kidney transplant recipients receiving low dose mycophenolate and its association with UGT2B7 polymorphisms.

BACKGROUND: Despite use of a lower mycophenolate dose in Thai kidney transplant patients, acceptable graft and patient outcomes can be achieved. We therefore examined the pharmacokinetics of mycophenolic acid (MPA) by area under the curve (AUC) and investigated genetic contribution in mycophenolate metabolism in this population. METHODS: Kidney transplant recipients with stable graft function who were receiving mycophenolate mofetil 1,000 mg/d in combination with either cyclosporine or tacrolimus, and prednisolone were studied. The MPA concentration was measured by fluorescence polarization immunoassay (FPIA), at predose and 1, 1.5, 2, 4, 6, 8, 10, and 12 hours after dosing. Genetic polymorphisms in UGT1A8, UGT1A9, and UGT2B7 were examined by denaturing high-performance liquid chromatography (DHPLC)-based single-base extension (SBE) analysis. RESULTS: A total 138 patients were included in study. The mean AUC was 39.49 mg-h/L (28.39-89.58 mg-h/L), which was in the therapeutic range. The correlation between the predose MPA concentration and AUC was poor. The mean AUC in the tacrolimus group was higher than that in the cyclosporine group. Polymorphisms in UGT2B7 showed significant association with AUC. CONCLUSION: Most of our patients with reduced mycophenolate dose had the AUC within the therapeutic range. Genetic polymorphisms in UGT2B7 may play a role in MPA metabolism in Thai kidney transplant patients.

The study on telomere length for age estimation in a Thai population.

Age is one of the key parameters in establishing a physical characteristic profile of an individual. For biological evidence left in crime scenes such as blood, saliva, hair, etc, the evidence owner's age can be determined only by DNA extracted from these materials. Previous researches have found that there are certain DNA regions with specialized characteristic and function called telomere being able to predict age. The present study was to determine the correlation between telomere length and age as well as the effect of sex on the correlation and to create linear regression equation for age estimation in Thai population for forensic purposes. Blood samples obtained from unrelated healthy Thai fresh cadavers without anatomical organ abnormalities were used in this study. All cadaver subjects underwent the postmortem examination in jurisdiction of the Department of Forensic Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, and Institute of Forensic Medicine, Police General Hospital. Fifty blood samples from both sexes of all ages divided into 6 groups for equal age distribution (0-11, 12-23, 24-35, 36-47, 48-59, and 60 years old and older) were collected for a total of 100 samples. The extracted genomic DNA samples were then subjected to telomere length estimation by terminal restriction fragment (TRF) assay. The results showed that the mean TRF length was inversely correlated with age (r = -0.625), and sex did not have a statistically significant influence on the association between age and mean TRF length (P > 0.05). The obtained linear regression equation was y = 113.538 ± 9.604 - 0.012 × (R = 0.391; P < 0.001). However, the correlation was too low to be used for age estimation with high certainty and a possible reason for this in part would be the postmortem DNA degradation at some level, even using fresh cadaver blood, and other biological factors such as ethnicity and DNA sources. Roughly, those individuals who had a mean TRF length longer than 6.3 kilobase (kb), between 5.5 and 6.3 kb, and shorter than 5.5 kb aged younger than 28 years, 30 to 44 years, and older than 46 years, respectively (P < 0.01). As a preliminary study, this study highlighted that telomere length could act as a useful biomarker of aging in human population and might be used for rough age estimation in a Thai population. However, further studies with a larger sample size and/or in living human bloods as well as other cell types are recommended to support the results of this study.

Whole exome sequencing in Thai patients with retinitis pigmentosa reveals novel mutations in six genes.

PURPOSE: To identify disease-causing mutations and describe genotype-phenotype correlations in Thai patients with nonsyndromic retinitis pigmentosa (RP). METHODS: Whole exome sequencing was performed in 20 unrelated patients. Eighty-six genes associated with RP, Leber congenital amaurosis, and cone-rod dystrophy were analyzed for variant detection. RESULTS: Seventeen variants (13 novel and 4 known) in 13 genes were identified in 11 patients. These variants include 10 missense substitutions, 2 nonsense mutations, 3 deletions, 1 insertion, and 1 splice site change. Nine patients with identified inheritance patterns carried a total of 10 potentially pathogenic mutations located in genes CRB1, C8orf37, EYS, PROM1, RP2, and USH2A. Three of the nine patients also demonstrated additional heterozygous variants in genes ABCA4, GUCY2D, RD3, ROM1, and TULP1. In addition, two patients carried variants of uncertain significance in genes FSCN2 and NR2E3. The RP phenotypes of our patients were consistent with previous reports. CONCLUSIONS: This is the first report of mutations in Thai RP patients. These findings are useful for genotype-phenotype comparisons among different ethnic groups.