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.

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.

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.

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.

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.

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.

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.

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.

Argininosuccinate synthetase deficiency: mutation analysis in 3 Thai patients.

Remarkable improvements in public health, nutrition, hygiene, and availability of medical services in the last 20 years have significantly reduced infant and childhood mortality in Thailand. Therefore, many rare and previously unidentified genetic disorders, which, in the past, usually led to the death of affected infants before a definitive diagnosis, have now been increasingly recognized. Recently, we identified three unrelated patients from Thailand who suffered from citrullinemia, one of five inherited types of urea cycle disorders. All were diagnosed within their first few weeks of life. Biochemical analyses, including plasma amino acid and urine organic acid profiles, are consistent with argininosuccinate synthetase (ASS) deficiency. Extensive mutation study by direct genomic sequencing of ASS demonstrated a homozygous G117S mutation in one patient and homozygous R363W mutations in the other two families.

The molecular basis of mucopolysaccharidosis type I in two Thai patients.

Two Thai patients diagnosed with Hurler syndrome (mucopolysaccharidosis type 1, MPS I) were found to have no detectable alpha-iduronidase (E.C. 3.2.1.76) activity in leukocytes, while normal Thai children all had significant activity, with a mean of 135 +/- 30 nmol/mg/18h. One patient was heterozygous for A75T (311G>A) and S633L (1986C>T) mutation, previously reported to cause MPS I, together with 9 other heterozygous polymorphisms also found in normal controls. The other patient had the previously described frameshift mutation 252insert C and a new nonsense mutation E299X (983G>T).

Fetal warfarin syndrome.

Fetuses exposed to Warfarin in the first trimester of pregnancy have an increased risk of embryopathy which consists of nasal hypoplasia and stippled epiphyses, known as fetal warfarin syndrome or warfarin embryopathy. We herein report a first case of an infant with fetal warfarin syndrome in Thailand. The patient was an offspring of a 34-year-old mother with history of SLE and arterial embolism for several years. She had an unplanned pregnancy while taking warfarin. The patient developed difficulty breathing in the first few hours after birth from severe nasal hypoplasia. He also had short limbs, brachydactyly, nail hypoplasia, and calcifications in the epiphyseal regions of humeri, femora and vertebrae radiographically. The patient eventually died from respiratory failure at 6 months of age.

Neural tube defects at Siriraj Hospital, Bangkok, Thailand--10 years review (1990-1999).

OBJECTIVES: Neural tube defects (NTDs), (including anencephaly, meningomyelocele and encephalocele), are among the most common birth defects, with high associated mortality and morbidity. NTDs occur in 1-5 per 1,000 births, with marked geographic and ethnic variations. However, there are few data concerning the incidence, associated anomalies, treatment and outcome of NTDs in Thailand. The objective of this study is to analyze data on NTD cases from 1990-1999 at Siriraj Hospital, a hospital with 18,000-20,000 deliveries annually. MATERIAL AND METHOD: A retrospective chart review of patients with NTDs who were born at or referred to Siriraj Hospital 1990-1999 was performed. RESULTS: During the 10 year period we examined, there were 115 patients with NTDs treated in the Department of Pediatrics as well as in other Departments at Siriraj Hospital. The incidence of NTD is 0.67 per 1,000 births. The sex distribution was equal among NTD cases, 55 (48%) females, 59 (51%) males and one (1%) unidentified sex. Isolated NTDs accounted for 105 (91%) cases, and 10 (8.7%) had at least 1 other structural anomaly such as cleft lip/palate, imperforate anus, amniotic band sequence, or ambiguous genitalia. Among all NTD cases, there were 55 (48%) with myelomeningocele, 45 (39%) with anencephaly, and 14 (12%) with encephalocele. Seventeen (15%) cases died; among these, 7 (41% of deaths) died in utero, 8 (47% of deaths) died in the early neonatal period, and 2 (12%) died after 1 year of age. Regarding treatment, 95 surgical corrections, 47 excisions and repairs, 45 excisions and VP shunts, 1 laminectomy and 2 club feet corrections were performed. CONCLUSIONS: In this hospital-based study of 115 patients with NTD, we found an incidence of 0.67/1000 births; however, as this was a hospital-based study, the community incidence is likely higher. Most cases were isolated NTDs, and almost half of NTDs were meningomyelocele. There was a high rate of mortality. Further studies are warranted to better elucidate the health burden from NTDs in Thailand. Public health interventions aimed at increasing the periconceptional consumption of folic acid should be implemented or enhanced to reduce the incidence of NTDs in Thailand.

Retrospective study of patients with suspected inborn errors of metabolism at Siriraj Hospital, Bangkok, Thailand (1997-2001).

INTRODUCTION: This retrospective clinical study was carried out on patients with suspected inborn errors of metabolism (IEM) at Siriraj Hospital during 1997-2001. The authors investigated 114 patients by quantitative plasma amino acid analysis. OBJECTIVE: The objective of this study was to collect and analyze epidemiologic and specific clinical data of IEM, especially in small-molecule diseases. MATERIAL AND METHOD: All patients were categorized into 2 major groups. 1) positive diagnoses for IEM 2) negative diagnoses for IEM. The two groups were investigated, studied including statistical analysis. RESULTS: The authors found that most IEM ascertained through plasma amino acid analysis were small-molecule diseases (74.3%) and amino acid disorders consisted of the most frequent disorders. The presented data demonstrated that the ratio of positive diagnoses to all patients studied was 1:8. Epidemiological data showed there were more male than female patients. Onset of diseases occurred predominantly during the first month of age, and was rarely found after 3 years of age. There were histories of consanguinity in half of the IEM patients. The most common presenting symptom was acute metabolic encephalopathy and specific signs for small-molecule disorders included hepatomegaly, unusual urine odor, acidosis, hyperammonemia, alteration of consciousness, and ketosis/ketonuria. These signs or symptoms indicated further metabolic investigations. CONCLUSION: Comparison of the data from Thailand with other countries showed both similarities and differences to the Caucasian population. Thus, further studies in IEM are much needed for the Thai population.

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.

Identification of 16 novel mutations in the argininosuccinate synthetase gene and genotype-phenotype correlation in 38 classical citrullinemia patients.

Classical citrullinemia (CTLN1), a rare autosomal recessive disorder, is caused by mutations of the argininosuccinate synthetase (ASS) gene, localized on chromosome 9q34.1. ASS functions as a rate-limiting enzyme in the urea cycle. Previously, we identified 32 mutations in the ASS gene of CTLN1 patients mainly in Japan and the United States, and to date 34 different mutations have been described in 50 families worldwide. In the present study, we report ASS mutations detected in 35 additional CTLN1 families from 11 countries. By analyzing the entire coding sequence and the intron-exon boundaries of the ASS gene using RT-PCR and/or genomic DNA-PCR, we have identified 16 novel mutations (two different 1-bp deletions, a 67-bp insertion, and 13 missense) and have detected 12 known mutations. Altogether, 50 different mutations (seven deletion, three splice site, one duplication, two nonsense, and 37 missense) in 85 CTLN1 families were identified. On the basis of primary sequence comparisons with the crystal structure of E. coli ASS protein, it may be concluded that any of the 37 missense mutations found at 30 different positions led to structural and functional impairments of the human ASS protein. It has been found that three mutations are particularly frequent: IVS6-2A>G in 23 families (Japan: 20 and Korea: three), G390R in 18 families (Turkey: six, U.S.: five, Spain: three, Israel: one, Austria: one, Canada: one, and Bolivia: one), and R304W in 10 families (Japan: nine and Turkey: one). Most mutations of the ASS gene are "private" and are distributed throughout the gene, except for exons 5 and 12-14. It seems that the clinical course of the patients with truncated mutations or the G390R mutation is early-onset/severe. The phenotype of the patients with certain missense mutations (G362V or W179R) is more late-onset/mild. Eight patients with R86H, A118T, R265H, or K310R mutations were adult/late-onset and four of them showed severe symptoms during pregnancy or postpartum. However, it is still difficult to prove the genotype-phenotype correlation, because many patients were compound heterozygotes (with two different mutations), lived in different environments at the time of diagnosis, and/or had several treatment regimes or various knowledge of the disease.