Homozygosity for a Rare Plec Variant Suggests a Contributory Role in Congenital Insensitivity to Pain.

Congenital insensitivity to pain is a rare human condition in which affected individuals do not experience pain throughout their lives. This study aimed to identify the molecular etiology of congenital insensitivity to pain in two Thai patients. Clinical, radiographic, histopathologic, immunohistochemical, and molecular studies were performed. Patients were found to have congenital insensitivity to pain, self-mutilation, acro-osteolysis, cornea scars, reduced temperature sensation, tooth agenesis, root maldevelopment, and underdeveloped maxilla and mandible. The skin biopsies revealed fewer axons, decreased vimentin expression, and absent neurofilament expression, indicating lack of dermal nerves. Whole exome and Sanger sequencing identified a rare homozygous variant c.4039C>T; p.Arg1347Cys in the plakin domain of Plec, a cytolinker protein. This p.Arg1347Cys variant is in the spectrin repeat 9 region of the plakin domain, a region not previously found to harbor pathogenic missense variants in other plectinopathies. The substitution with a cysteine is expected to decrease the stability of the spectrin repeat 9 unit of the plakin domain. Whole mount in situ hybridization and an immunohistochemical study suggested that Plec is important for the development of maxilla and mandible, cornea, and distal phalanges. Additionally, the presence of dental anomalies in these patients further supports the potential involvement of Plec in tooth development. This is the first report showing the association between the Plec variant and congenital insensitivity to pain in humans.

Phenotypic and molecular features of Thai patients with primary carnitine deficiency.

BACKGROUND: Primary carnitine deficiency (PCD) is screened by expanded newborn screening (NBS) using tandem mass spectrometry (MS/MS) that can detect both affected neonates and mothers. This study aimed to delineate the clinical, biochemical, and molecular findings of Thai PCD patients. METHODS: Expanded NBS using MS/MS was implemented in Bangkok and 146,757 neonates were screened between 2014 and 2018. PCD was screened by low free carnitine (C0) levels in dried blood spots. Plasma C0 levels and C0 clearance values were measured in neonates and their mothers with positive screening results. Clinically diagnosed cases were described. The coding regions and intron-exon boundaries of the SLC22A5 gene were sequenced in all cases with low plasma C0 levels. RESULTS: There were 14 cases with confirmed PCD: two clinically diagnosed cases, and 12 cases identified through NBS including five newborns, six mothers, and one older sibling. Thus, the incidence of PCD in neonates was 1:29,351. All affected neonates and mothers were asymptomatic except one mother with dilated cardiomyopathy. SLC22A5 gene sequencing identified biallelic causative variants in all cases, comprising 10 different variants of which four were novel. c.51C > G (p.Phe17Leu) and c.760C > T (p.Arg254Ter) were the most prevalent variants in this study. Cases with significant clinical features tended to have higher C0 clearance values. CONCLUSIONS: Primary carnitine deficiency is a common inherited metabolic disorder (IMD) in Thailand. Our findings broaden the spectrum of SLC22A5 variants. The future national NBS program will shed more light on PCD and other IMDs in Thailand.

Molecular characterization of Thai patients with phenylalanine hydroxylase deficiency and in vitro functional study of two novel PAH variants.

Phenylketonuria (PKU) is an autosomal recessive amino acid metabolism disorder caused by variants in the gene encoding phenylalanine hydroxylase (PAH; EC1.14.16.1). This study aimed to assess the specific heterogeneity of PAH variants found in Thai population as well as evaluate enzyme activity and expression of novel variants. PAH gene from 13 patients was analyzed by PCR amplification and direct Sanger-sequencing of 13 exons of the coding region. The novel variants were transiently transfected in COS-7 cells for functional verification. Eleven different PAH variants were identified: all pathogenic variants were missense variants, of which the most frequent variant was p.R169L, accounting for 24% (6/25) of all identified alleles. Two novel variants p.R169L and p.Y317N and previously reported variants with mutated residues at the same positions (p.R169H and p.Y317H) were expressed in COS-7 cells. These showed mildly impaired residual activity levels (42.3-63.1% of wild type), while the protein levels were well expressed (82.8-110%), except for p.R169L, which showed decreased protein expression of 55.7% compared to the wild type enzyme. All subjects with p.R169L identified in at least one of pathogenic alleles (one case is homozygous) had a metabolic phenotype of mild hyperphenylalaninemia (HPA). Our data has expanded the information on the genetic heterogeneity of Thai patients with PAH deficiency. This finding emphasizes the importance of genotyping in patients with HPA, and in vitro studies can provide additional information for prediction of phenotype.

Asia Pacific Society of Human Genetics (APSHG) from conception to 2019: 13 years of collaboration to tackle congenital malformation and genetic disorders in Asia.

Putting together the reports in this issue that come from a representation of the different countries in Asia presents an opportunity to share the unique story of the Asia Pacific Society of Human Genetics (APSHG), which has provided the authors of many of these articles. This paper, authored by the Past Presidents of the Society, shares glimpses of how medical genetics activities were first organized in the Asia Pacific region and provides interesting corollaries on how under-developed and developing countries in this part of the world had developed a unique network for exchange and sharing of expertise and resources. Although APSHG was formally registered as a Society in Singapore in 2006, the Society has its origins as far back as in the 1990s with members from different countries meeting informally, exchanging ideas, and collaborating. This treatise documents the story of the experiences of the Society and hopes it will provide inspiration on how members of a genetics community can foster and build a thriving environment to promote this field.

Analysis of Novel Mutations and Methylmalonyl-CoA Mutase Levels in Thai Patients with Isolated Methylmalonic Acidemia.

Isolated methylmalonic acidemia (MMA) is an autosomal recessive, inherited disorder that results from either a mut defect of the methylmalonyl-CoA mutase apoenzyme (MCM, the product of the MUT gene) or a cbl defect in the synthesis of its cofactor, adenosylcobalamin (AdoCbl). In this study, biochemical and mutational analyses of three patients clinically diagnosed with MMA were performed. No MCM activity was detected in leukocyte extracts of two patients, while high MCM activity was found in the other, suggesting mut (0) and cbl defects, respectively. A novel (c.IVS6 -3 to -8delCTTTTT, p.K444_L445insFC*) and two known mutations in the MUT gene and one novel (c.227_36delGACCCAAAGA, p.R76Mfs*14) mutation in the MMAB gene were identified. In addition, MCM immunoblot analysis of leukocyte extract samples of these three patients and eight patients previously reported by our group, as well as their parents, showed a good correlation between the MCM protein and activity levels. Patients with mut (0) defective subtypes lacked MCM activity and had no MCM band, while patients carrying the cbl defects had high MCM activity levels and an intense MCM band at about 83 kDa, in comparison to those in their parents. These data expand the mutation spectrum of MMA deficiency. In addition, the examination of MCM protein level may be used as an alternative technique to determine the mut (0) and cbl defective subgroups.

An Economic Evaluation of Neonatal Screening for Inborn Errors of Metabolism Using Tandem Mass Spectrometry in Thailand.

BACKGROUND: Inborn errors of metabolism (IEM) are a rare group of genetic diseases which can lead to several serious long-term complications in newborns. In order to address these issues as early as possible, a process called tandem mass spectrometry (MS/MS) can be used as it allows for rapid and simultaneous detection of the diseases. This analysis was performed to determine whether newborn screening by MS/MS is cost-effective in Thailand. METHOD: A cost-utility analysis comprising a decision-tree and Markov model was used to estimate the cost in Thai baht (THB) and health outcomes in life-years (LYs) and quality-adjusted life year (QALYs) presented as an incremental cost-effectiveness ratio (ICER). The results were also adjusted to international dollars (I$) using purchasing power parities (PPP) (1 I$ = 17.79 THB for the year 2013). The comparisons were between 1) an expanded neonatal screening programme using MS/MS screening for six prioritised diseases: phenylketonuria (PKU); isovaleric acidemia (IVA); methylmalonic acidemia (MMA); propionic acidemia (PA); maple syrup urine disease (MSUD); and multiple carboxylase deficiency (MCD); and 2) the current practice that is existing PKU screening. A comparison of the outcome and cost of treatment before and after clinical presentations were also analysed to illustrate the potential benefit of early treatment for affected children. A budget impact analysis was conducted to illustrate the cost of implementing the programme for 10 years. RESULTS: The ICER of neonatal screening using MS/MS amounted to 1,043,331 THB per QALY gained (58,647 I$ per QALY gained). The potential benefits of early detection compared with late detection yielded significant results for PKU, IVA, MSUD, and MCD patients. The budget impact analysis indicated that the implementation cost of the programme was expected at approximately 2,700 million THB (152 million I$) over 10 years. CONCLUSION: At the current ceiling threshold, neonatal screening using MS/MS in the Thai context is not cost-effective. However, the treatment of patients who were detected early for PKU, IVA, MSUD, and MCD, are considered favourable. The budget impact analysis suggests that the implementation of the programme will incur considerable expenses under limited resources. A long-term epidemiological study on the incidence of IEM in Thailand is strongly recommended to ascertain the magnitude of problem.

Carnitine-acylcarnitine translocase deficiency: Two neonatal cases with common splicing mutation and in vitro bezafibrate response.

BACKGROUND: Mitochondrial fatty acid oxidation (FAO) disorders are among the causes of acute encephalopathy- or myopathy-like illness. Carnitine-acylcarnitine translocase (CACT) deficiency is a rare FAO disorder, which represent an energy production insufficiency during prolonged fasting, febrile illness, or increased muscular activity. CACT deficiency is caused by mutations of the SLC25A20 gene. Most patients developed severe metabolic decompensation in the neonatal period and died in infancy despite aggressive treatment. PATIENTS AND METHODS: We herein report the clinical findings of two unrelated cases of CACT deficiency with mutation confirmation, and in vitro bezafibrate responses using in vitro probe acylcarnitine (IVP) assay. Patients 1 and 2 are products of nonconsanguineous parents. Both patients developed cardiac arrest at day 3 of life but survived the initial events. Their blood chemistry revealed hypoglycemia and metabolic acidosis. The acylcarnitine profiles in both patients demonstrated increased long-chain acylcarnitines, suggesting CACT or carnitine palmitoyltransferase-2 (CPT2) deficiency. RESULTS: The mutation analysis identified homozygous IVS2-10T>G in the SLC25A20 gene in both patients, confirming the diagnosis of CACT deficiency. The IVP assay revealed increased C16, C16:1, but decreased C2 with improvement by bezafibrate in the cultured fibroblasts. The short-term clinical trial of bezafibrate in Patient 1 did not show clinical improvement, and died after starting the trial for 6 months. CONCLUSION: This splicing mutation has been identified in other Asian populations indicating a possible founder effect. IVP assay of cultured fibroblasts could determine a response to bezafibrate treatment. A long-term clinical trial of more enrolled patients is required for evaluation of this therapy.

Clinical characteristics and mutation analysis of propionic acidemia in Thailand.

BACKGROUND: Propionic acidemia (PA) is caused by a deficiency of propionyl CoA carboxylase. A characteristic urine organic acid profile includes 3-hydroxypropionate, methylcitrate, tiglylglycine, and propionylglycine. The diagnosis of PA is confirmed by detection of mutations in the PCCA or PCCB genes. We herein report the clinical and molecular findings of four Thai patients with PA. METHODS: Clinical findings of four Thai patients with PA were retrospectively reviewed. Urine organic acids were analyzed by gas chromatography-mass spectrometry. PCR-sequencing analyses of encoding exons and intron/exon boundaries of the PCCA and PCCB genes were performed. RESULTS: All patients had neonatal onset of PA. One patient died of cardiomyopathy, and another one of pneumonia and metabolic decompensation. The remainder experienced significant neurocognitive impairment. Mutation analysis of the PCCA gene identified homozygous c.1284+1G>A in patient 1, c.230G>A (p.R77Q) and c.1855C>T (p.R619X) in patient 2, homozygous c.2125T>C (p.S709P) in patient 3, and only one mutant allele, c.231+1G>T in patient 4. No PCCB mutation was identified. Four mutations including c.230G>A, c.231+1G>T, c.1855C>T, and c.2125T>C have not been reported previously. CONCLUSIONS: The clinical and molecular study of these Thai patients provided additional knowledge of the genotype and phenotype characteristics of PA. The results of the study suggested that PCCA mutations in Asian populations were distinct from those of other populations.

Genetic counseling/consultation in South-East Asia: a report from the workshop at the 10th Asia pacific conference on human genetics.

This paper reports on the workshop 'Genetic Counseling/Consultations in South-East Asia' at the 10(th) Asia Pacific Conference on Human Genetics in Kuala Lumpur, Malaysia, in December 2012. The workshop brought together professionals and language/communication scholars from South-East Asia, and the UK. The workshop aimed at addressing culture- and context-specific genetic counseling/consultation practices in South-East Asia. As a way of contextualizing genetic counseling/consultation in South-East Asia, we first offer an overview of communication-oriented research generally, drawing attention to consultation and counseling as part of a communicative continuum with distinctive interactional features. We then provide examples of genetic counseling/consultation research in Hong Kong. As other countries in South-East Asia have not yet embarked on communication-oriented empirical research, we report on the current practices of genetic counseling/consultation in these countries in order to identify similarities and differences as well as key obstacles that could be addressed through future research. Three issues emerged as 'problematic': language, religion and culture. We suggest that communication-oriented research can provide a starting point for evidence-based reflections on how to incorporate a counseling mentality in genetic consultation. To conclude, we discuss the need for creating a platform for targeted training of genetic counselors based on communication-oriented research findings.

Current diagnosis and management of mucopolysaccharidosis VI in the Asia-Pacific region.

INTRODUCTION: Mucopolysaccharidosis (MPS) type VI (Maroteaux-Lamy syndrome) is a clinically heterogeneous lysosomal storage disorder. It presents significant diagnostic and treatment challenges due to the rarity of the disease and complexity of the phenotype. As information about MPS VI in Asia-Pacific countries is limited, a survey was conducted to assess current practices for diagnosis and management of MPS VI in this region. The participants were selected based on their experience in diagnosing and managing MPS patients. METHODS: The survey comprised 29 structured quantitative or qualitative questions. Follow-up consultations were undertaken to discuss the data further. RESULTS: Thirteen physicians from eight countries or regions (Australia, China, Hong Kong, Japan, Malaysia, Philippines, Taiwan and Thailand) were surveyed. At the time of the survey twenty-two patients with MPS VI were directly treated by the respondents and most (~80%) had rapidly progressing disease. A wide range of medical specialists are involved in managing patients with MPS VI, the most common being orthopedic surgeons, pediatricians and geneticists. The availability/accessibility of diagnostic tools, therapies and national insurance coverage vary greatly across the countries/regions and, in some cases, between different regions within the same country. Currently, there are national MPS management groups in Australia and Japan. Australia, Taiwan and Hong Kong have local guidelines for managing MPS and local MPS registries are available in Australia, Taiwan, and Japan. CONCLUSIONS: This survey highlights differences in the diagnosis and management of MPS VI between Asia-Pacific countries/regions. Important barriers to advancing the identification, understanding and treatment of MPS VI include the paucity of epidemiological information, limited access to laboratory diagnostics and therapies, low disease awareness, and a lack of monitoring and treatment guidelines. There is a clear need to facilitate communications between physicians and establish regional or national disease registries, a multidisciplinary referral network, and a centralized diagnostic and management framework.

Clinical and molecular findings in Thai patients with isolated methylmalonic acidemia.

Isolated methylmalonic acidemia (MMA) is a genetically heterogeneous organic acid disorder caused by either deficiency of the enzyme methylmalonyl-CoA mutase (MCM), or a defect in the biosynthesis of its cofactor, adenosyl-cobalamin (AdoCbl). Herein, we report and review the genotypes and phenotypes of 14 Thai patients with isolated MMA. Between 1997 and 2011, we identified 6 mut patients, 2 cblA patients, and 6 cblB patients. The mut and cblB patients had relatively severe phenotypes compared to relatively mild phenotypes of the cblA patients. The MUT and MMAB genotypes were also correlated to the severity of the phenotypes. Three mutations in the MUT gene: c.788G>T (p.G263V), c.809_812dupGGGC (p.D272Gfs*2), and c.1426C>T (p.Q476*); one mutation in the MMAA gene: c.292A>G (p.R98G); and three mutations in the MMAB gene: c.682delG (p.A228Pfs*2), c.435delC (p.F145Lfs*69), and c.585-1G>A, have not been previously reported. RT-PCR analysis of a common intron 6 polymorphism (c.520-159C>T) of the MMAB gene revealed that it correlates to deep intronic exonization leading to premature termination of the open reading frame. This could decrease the ATP:cobalamin adenosyltransferase (ATR) activity resulting in abnormal phenotypes if found in a compound heterozygous state with a null mutation. We confirm the genotype-phenotype correlation of isolated MMA in the study population, and identified a new molecular basis of the cblB disorder.

Amino acid disorders detected by quantitative amino acid HPLC analysis in Thailand: an eight-year experience.

BACKGROUND: Amino acid disorders are a major group of inborn errors of metabolism (IEM) with variable clinical presentations. This study was aimed to provide the data of amino acid disorders detected in high-risk Thai patients referred to our metabolic lab from all over the country. METHODS: From 2001 to 2009, we analyzed amino acids by HPLC in 1214 plasma and cerebrospinal fluid specimens. These specimens were obtained from patients with clinical suspicion of IEM or with positive newborn screening. The clinical data of the patients with confirmed diagnoses of amino acid disorders were also analyzed. RESULTS: Fifty-eight patients were diagnosed with amino acid disorders, including 20 cases (34.5%) with maple syrup urine disease, 13 (22.4%) with phenylketonuria and hyperphenylalaninemia, 13 (22.4%) with nonketotic hyperglycinemia, 9 (15.5%) with urea cycle defects, 2 (3.4%) with classical homocystinuria, and 1 (1.7%) with ornithine aminotransferase deficiency. There was considerable delay in diagnoses which led to poor outcomes in most patients. CONCLUSION: The prevalence of amino acid disorders in Thailand is distinct from other countries. This will guide the selection of the prevalent IEM for the future expansion of newborn screening program in this country.

Phenotypic and mutation spectrums of Thai patients with isovaleric acidemia.

BACKGROUND: Isovaleric acidemia (IVA) is an autosomal recessive disorder caused by deficiency of isovaleryl-CoA dehydrogenase (IVD). Clinical features include vomiting, lethargy, metabolic acidosis, and "sweaty feet" odor. The pathognomonic metabolite, isovalerylglycine, is detected on urine organic acid analysis. Clinical diagnosis of IVA can be confirmed on mutation analysis of the IVD gene. METHODS: The cases of five unrelated Thai patients with IVA, identified on urine organic acid analysis, are described. Mutation analysis of the IVD gene was performed using polymerase chain reaction sequencing of the entire coding regions. RESULTS: Four out of the five IVA patients had an acute neonatal form. The hematologic abnormalities were common and thus could be presenting symptoms in the absence of metabolic acidosis. As for the neurological outcome, only one patient had normal intelligence. Mutation analysis of the IVD gene identified the mutations c.457-3_2CA>GG, c.1199A>G (p.Y371C), c.281C>G (p.A65G), c.358G>A (p.G91R), and c.827T>C (p.L247P). The poor outcome in most patients might be explained by the delayed diagnosis and initial unavailability of the metabolic formulas and medications in Thailand. The c.457-3_2CA>GG mutation was identified in all of the present patients. This suggests that it is the most common mutation in the Thai population. Therefore, it could be a founder mutation in Thai subjects. One of the present Thai IVA patients also had the p.Y371C mutation, which is common in Han Chinese subjects. In addition, two novel mutations, p.A65G and p.L247P, were identified. CONCLUSION: The present study provides additional knowledge on the genotype-phenotype of IVA, suggesting that IVD mutations in Asian populations are distinct from these in Western populations.

Glutaric aciduria type 2, late onset type in Thai siblings with myopathy.

Reported here is a novel presentation of late onset glutaric aciduria type 2 in two Thai siblings. A 9-year-old boy presented with gradual onset of proximal muscle weakness for 6 weeks. The initial diagnosis was postviral myositis, and then polymyositis. Electromyography and nerve conduction velocity testing indicated a myopathic pattern. Muscle biopsy revealed excessive accumulation of fat. Acylcarnitine profiling led to the diagnosis of glutaric aciduria type 2. Immunoblot analysis of electron-transferring-flavoprotein and its dehydrogenase electron-transferring-flavoprotein dehydrogenase led to mutation analysis of the ETFDH gene, which revealed two different pathogenic mutations in both alleles and confirmed the diagnosis of glutaric aciduria type 2 caused by electron-transferring-flavoprotein dehydrogenase deficiency. The boy recovered completely after treatment. Later, his younger sibling became symptomatic; the same diagnosis was confirmed, and treatment was similarly effective. Acylcarnitine profiling was a crucial investigation in making this diagnosis in the presence of normal urine organic acid findings. Late onset glutaric aciduria type 2, a rare cause of muscle weakness in children, should be included in the differential diagnosis of myopathy.

Down syndrome parents' support group in Thailand Siriraj Hospital, fifteen years experience: a review.

Down Syndrome Parents' Support Group Siriraj Hospital was established on February 14, 1993. It consists of a group of pediatricians, nurses, parents of children with Down Syndrome (DS) who received care at the Genetics Clinic, Division of Medical Genetics, Department of Pediatrics, Faculty of Medicine Siriraj Hospital. The objective is to educate parents with DS children whose diagnosis of DS given at birth causing grief and disappointment which led to abandonment of these children at Siriraj Hospital almost every other month (fifteen years ago) due to lack of education on the part of the medical professionals. Down Syndrome Parents' Support Group Siriraj Hospital received financial support from Terres des hommes of the Netherlands in the first 6 years. Later it received partial financial support from a government agency; however, the majority of the funding came from private donations. Throughout the years, the group had several successful activities: Siriraj Down Syndrome Annual Meeting since 1991 (total of 17 years) and Down Syndrome Provincial Lecture tour, so called "Down Sunjorn" since 1997. The latest in 2008 (the tenth) which was organized with major provincial hospitals of the Ministry of Public Health (MOPH). Moreover the group took part in (1) working with the Ministry of Education for Thailand Educational Act B.E. 1999 which promotes integration of DS children into normal schools all over the country, (2) working with the Department of Maternal & Child Health, MOPH started the Child Development Center in the provincial community hospitals where the service was lacking; (3) working with Ministry of Social Development' and Human Security to initiate an educational program for the DS families in the rural areas (from 2001 - 2006) to help educate families with DS children and raise awareness for their educational & legal rights. In the past 15 years, there was no more abandonment of DS children at Siriraj Hospital and others; these children received better care and improved quality of life.

Factors influencing development of Down syndrome children in the first three years of life: Siriraj experience.

OBJECTIVE: To analyze factors influencing development of Down syndrome children in the first three years of life. MATERIAL AND METHOD: A cross-sectional study was conducted in 100 Down syndrome (DS) children attending at the Genetics clinic, Department of Pediatrics, Siriraj Hospital between January 2002 and December 2005. All individuals were three to six years of age. The data was collected from January to December 2006, including general information and factors on the child and their families. The child developmental quotient (DQ) was evaluated by Capute Scales Cognitive Adaptive Test/Clinical Linguistic & Auditory Milestones Scale (CAT/CLAMS) at three years of age. Data were analyzed by descriptive statistic and multiple linear regression with the significant level at p-value < 0. 05. RESULTS: The mean development quotient (DQ) was 63.78 +/- 11.25 (range 32-91) with the majority being mild developmental delay. The child and family factors contributing to developmental quotient (DQ) outcome were birthplace, congenital heart disease, age at the first genetic counseling, regular follow-up in the Genetics clinic, age at the first early stimulation program/speech training program, parental education/occupation, and family income. Only family income and age at the first speech-training program were found to be independently associated with developmental quotient (DQ) at the age of three years (p-value < 0.05). CONCLUSION: Down syndrome is the most common genetic cause of mental retardation. Various factors contribute to developmental quotient (DQ) outcome but the most important factors are family income and age at the first speech-training program. Therefore, Down syndrome children with the above factors should be followed-up and monitored closely for the optimal long-term outcome.

Organic acid disorders detected by urine organic acid analysis: twelve cases in Thailand over three-year experience.

BACKGROUND: Disorders of organic acid (OA) metabolism are generally detected by qualitative analysis of urine organic acids by gas chromatography/mass spectrometry (GC/MS) which was well established in developed countries since 1980s. Confirmation of the diagnosis of organic acid disorders by OA analysis, enzyme analysis and molecular study is a difficult task in developing countries. METHODS: During 2001-2004, we had analysed 442 urine samples in 365 patients and identified 12 cases of organic acid disorders. RESULTS: We identified the following disorders: alkaptonuria (ALK)=1, isovaleric acidemia (IVA)=3, propionic acidemia (PA)=2, methylmalonic acidemia (MMA)=3, glutaric aciduria, type I (GA-I)=1, multiple carboxylase deficiency (MCD)=1, and glutaric acidemia, type II (GA-II)=1. CONCLUSIONS: OA disorders had never been diagnosed in Thailand before, until GC/MS technology was introduced to Thailand in 2001. Urine OA analysis also provided a diagnostic clue to other inborn errors of metabolism including amino acid disorders, urea cycle disorders, disorders of carbohydrate metabolism, and mitochondrial fatty acid oxidation disorders. Since then, we were able to diagnose numerous disorders, which led to prompt treatment and better outcome in our patients.

Organising services for IMD in Thailand: twenty years experience.

The study of inherited metabolic disorders (IMD) in Thailand is in its infancy when compare with developed countries. Prior to 1987, majority of these disorders were clinically diagnosed since there were only a handful of clinicians and scientists with expertise in inborn errors of metabolism, lack of well-equipped laboratory facilities and government support. In developing countries, inherited metabolic disorders are not considered a priority due to the prevalence of infectious diseases such as HIV infection and congenital infections. A multicentre survey conducted in 1994 and 2001 revealed the existence of numerous cases of IMD from all over the country. Case reports and publications on IMD in Thai (and international) medical journals in past 20 years had undoubtedly raised its awareness among Thai paediatricians and scientists. In 2001, the Genetic Metabolic Centre was first established in Siriraj Hospital Faculty of Medicine, Thailand. Numerous new cases of IMD had been identified since then.

Highest accuracy of combined consensus clinical criteria and SNRPN gene molecular markers in diagnosis of Prader-Willi syndrome in Thai patients.

BACKGROUND: Prader-Willi Syndrome (PWS) is a complex human genetic disease arising from a loss of paternal allele expression of imprinting genes on chromosome 15q11-q13. Normally the CpG islands at this site are heavily methylated in the maternal allele, but unmethylated in the paternal allele and therefore activated in gene expression. only the methylated allele should present in pws patients when methylation-specific pcr (msp) is analyzed. METHODS: This paper reports an analysis of PWS in Thai patients using consensus diagnostic criteria based on a combination of clinical data, basic G-banding and fluorescence in situ hybridization (FISH) cytogenetics, PCR-based methylation assay, and bisulfite sequencing of the CpG islands of SNRPN to confirm 15q deletion or the methylation pattern of the SNRPN promoter and exon 1. Lack of complete clinical reports or inadequacy of the minimum laboratory support required had made it difficult to diagnose PWS, Angelman syndrome and other microdeletion disorders. RESULTS: Accuracy of 100% was obtained for diagnosis of the PWS study patients using the minimum requirements necessary. A total of 20 patients were diagnosed as PWS based on clinical criteria and the scoring tool for PWS, and the same approach was applied to four separate patients with some unmatched criteria but phenotypic similarity to PWS. Findings showed that 70% of those clinically diagnosed as PWS patients (14/20) had a deletion at 15q11-q13 according to FISH, while all 20 patients showed MSP positive of SNRPN gene. Six cases (30%) without a paternal deletion were confirmed to have maternal uniparental disomy (mUPD) of PWS by MSP and methylation sequencing approaches. Noteworthy, two of the six cases with mUPD were 3.5 year-old twins. None of the five cases with scores lower than the reported consensus criteria showed positive G-band, FISH or MSP results. CONCLUSIONS: We demonstrate here the high power of combining clinical findings, FISH and MSP in definitive diagnosis of PWS and in distinguishing between the two major different types of molecular mechanisms. No false positives or false negatives were observed in our analysis.

Novel mutations found in two genes of thai patients with isolated methylmalonic acidemia.

Molecular genetic analysis of three patients diagnosed with isolated methylmalonic acidemia (MMA) revealed that one was mut (0) MMA, with a mutation in the MUT gene encoding the L: -methylmalonyl-CoA mutase (MCM), and two were cblB MMA, with mutations in the MMAB gene required for synthesizing the deoxyadenosylcobalamin cofactor of MCM. The mut (0) patient was homozygous for a novel nonsense mutation in MUT, p.R31X (c.167C --> T), and heterozygous for three previously described polymorphisms, p.K212K (c.712A --> G), p.H532R (c.1671A --> G), and p.V671I (c.2087G --> A). The new MMAB mutation, p.E152X (c.454G --> T), was found to be homozygous in one cblB patient and heterozygous in the other patient, who also had four intron polymorphisms in this gene.