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.

Disseminated cryptococcosis in two boys with novel mutation of CD40 Ligand-Associated X-linked hyper-IgM syndrome.

X-linked hyper-IgM syndrome (XHIM) caused by CD40L mutations is a primary immunodeficiency condition that increases susceptibility to opportunistic infections. Disseminated cryptococcosis in XHIM is rarely reported in children. Here, we report two related boys who have a novel hemizygous frameshift c.208delC mutation of CD40L. They live in the western region of Thailand and developed disseminated cryptococcosis while receiving regular intravenous immunoglobulin supplementation.

A novel mutation of WAS gene in a boy with Mycobacterium bovis infection in spleen.

Wiskott-Aldrich syndrome (WAS) is a primary immunodeficiency disorder caused by mutations of the gene encoding WAS protein (WASp). A scoring system has been used to grade severity of the disease. However, the phenotype of the disease may progress over time, especially in children younger than 2 years of age. Here, we report a male child who presented with X-linked thrombocytopenia (XLT). Mutation analysis revealed a novel hemizygous 13-bp deletion (c.181_193delGCTGAGCACTGGA) on exon 2 of the WAS gene. This frameshift mutation resulted in a premature terminating codon at position 71 (p.A61fsX10). Molecular analysis of maternal DNA revealed a heterozygosity of the same mutation. The disease progressed to classic WAS within 8 months. Later, gastric varices as a consequence of Mycobacterium bovis infection in the spleen was detected. The rapid worsening of the disease may be due to the severe genotype of this patient.

Molecular Characterization of Hb H and AEBart's Diseases in Thai Children: Phramongkutklao Hospital Experiences.

Background: Alpha-thalassemia is a common genetic disorder in Thailand and is caused by either deletion or non-deletional mutation of one or both α-globin genes. Inactivation of three α-globin genes causes Hb H disease and interaction of Hb H disease with heterozygous Hb E results in AEBart's disease. Objective: The present study aimed to characterize the genotype of α-globin gene in 81 pediatric patients with Hb H and AEBart's diseases in Phramongkutklao Hospital, a tertiary care center for thalassemic patients in central Thailand. Material and Method: Eighty one unrelated pediatric patients including 60 patients with Hb H disease and 21 patients with AEBart's disease were enrolled in our study. Mutation analysis was performed by multiplex gap-PCR, multiplex-ARMS and direct DNA sequencing of both HBA1 and HBA2 genes, respectively. Results: A total of 81 pediatric patients with Hb H and AEBart's diseases who mainly lived in central Thailand were included in the present study. Eight different α-thalassemia mutations interacting to produce seven genotypes of α-globin gene in both Hb H and AEBart's diseases were identified. The number of patients in the non-deletional form was higher than in the deletional form for both Hb H (51.6% VS 48.4%) and AEBart's diseases (52.4% VS 47.6%). The SEA deletion (--SEA) was the most common (98.8%) α-thalassemia 1 mutation. While 3.7-kb deletion (-α3.7) was the most common (90%) α-thalassemia 2 deletion, Hb CS was the most common (90%) non-deletional a-thalassemia 2. Uncommon non-deletional α-thalassemia 2 mutation identified in our study were Hb QS, Hb PS and initiation codon mutation, respectively. Conclusion: All of the α-thalassemia mutation in our pediatric patients with Hb H and AEBart's diseases have been characterized by the combination of molecular techniques including multiplex gap-PCR, multiplex-ARMS and DNA sequencing of HBA1 and HBA2 genes.

Bone marrow failure and developmental delay caused by mutations in poly(A)-specific ribonuclease (PARN).

BACKGROUND: Deadenylation regulates RNA function and fate. Poly(A)-specific ribonuclease (PARN) is a deadenylase that processes mRNAs and non-coding RNA. Little is known about the biological significance of germline mutations in PARN. METHODS: We identified mutations in PARN in patients with haematological and neurological manifestations. Genomic, biochemical and knockdown experiments in human marrow cells and in zebrafish have been performed to clarify the role of PARN in the human disease. RESULTS: We identified large monoallelic deletions in PARN in four patients with developmental delay or mental illness. One patient in particular had a severe neurological phenotype, central hypomyelination and bone marrow failure. This patient had an additional missense mutation on the non-deleted allele and severely reduced PARN protein and deadenylation activity. Cells from this patient had impaired oligoadenylation of specific H/ACA box small nucleolar RNAs. Importantly, PARN-deficient patient cells manifested short telomeres and an aberrant ribosome profile similar to those described in some variants of dyskeratosis congenita. Knocking down PARN in human marrow cells and zebrafish impaired haematopoiesis, providing further evidence for a causal link with the human disease. CONCLUSIONS: Large monoallelic mutations of PARN can cause developmental/mental illness. Biallelic PARN mutations cause severe bone marrow failure and central hypomyelination.

The C-type lectin receptor CLEC4M binds, internalizes, and clears von Willebrand factor and contributes to the variation in plasma von Willebrand factor levels.

Genetic variation in or near the C-type lectin domain family 4 member M (CLEC4M) has been associated with plasma levels of von Willebrand factor (VWF) in healthy individuals. CLEC4M is a lectin receptor with a polymorphic extracellular neck region possessing a variable number of tandem repeats (VNTR). A total of 491 participants (318 patients with type 1 von Willebrand disease [VWD] and 173 unaffected family members) were genotyped for the CLEC4M VNTR polymorphism. Family-based association analysis on kindreds with type 1 VWD demonstrated an excess transmission of VNTR 6 to unaffected individuals (P = .0096) and an association of this allele with increased VWF:RCo (P = .029). CLEC4M-Fc bound to VWF. Immunofluorescence and enzyme-linked immunosorbent assay demonstrated that HEK 293 cells transfected with CLEC4M bound and internalized VWF. Cells expressing 4 or 9 copies of the CLEC4M neck region VNTR showed reduced interaction with VWF relative to CLEC4M with 7 VNTR (CLEC4M 4%-60% reduction, P < .001; CLEC4M 9%-45% reduction, P = .006). Mice expressing CLEC4M after hydrodynamic liver transfer have a 46% decrease in plasma levels of VWF (P = .0094). CLEC4M binds to and internalizes VWF, and polymorphisms in the CLEC4M gene contribute to variable plasma levels of VWF.

Combined de-novo mutation and non-random X-chromosome inactivation causing Wiskott-Aldrich syndrome in a female with thrombocytopenia.

OBJECTIVE: Disorders linked to mutations in the X chromosomes typically affect males. The aim of the study is to decipher the mechanism of disease expression in a female patient with a heterozygous mutation on the X-chromosome. PATIENTS AND METHODS: Clinical data was extracted from the Canadian Inherited Marrow Failure Registry. Genomic ribonucleic acid (DNA) and complementary DNA (cDNA) underwent Sanger sequencing. Protein analysis was performed by flow cytometry. X-inactivation patterns were analyzed by evaluating the DNA methylation status and cDNA clonal expression of several genes on the X-chromosome. SNP array was used for molecular karyotyping of the X-chromosome. RESULTS: A female with thrombocytopenia, eczema and mild T-lymphocyte abnormalities with extensive negative diagnostic testing, was suspected to have Wiskott-Aldrich syndrome (WAS)/X-linked thrombocytopenia. Although the girl had a mutation (c.397G > A, p.E133K) in only one allele, she was found to have an extremely skewed X-inactivation pattern and no expression of the WAS protein. Family studies using DNA methylation analysis and cDNA clonal expression of several genes on the X-chromosome demonstrated that the patient developed de-novo non-random inactivation of the X-chromosome that does not carry the mutation. Genome-wide high-density molecular karyotyping excluded deletions and amplifications as a cause for the non-random inactivation of one X-chromosome. CONCLUSIONS: Our study emphasizes the need to test selected female patients with complete or incomplete disease expression for X-linked disorders even in the absence of a family history.

Three novel homozygous ITGB2 mutations among two patients with leukocyte adhesion defect type-1: Two case reports.

BACKGROUND: A leukocyte adhesion defect (LAD) is a rare primary immunodeficiency disorder. LAD type 1 (LAD-1) is the most common, which is caused by ITGB2 mutation resulting in dysfunction of ß2 integrin, which impairs leukocyte adherence to the endothelium. CASE SUMMARY: The first two cases of LAD-1 in Thailand presented with recurrent omphalitis, soft tissue infection, marked leukocytosis, and neutrophilia. One patient experienced delayed umbilical cord separation. Mutation analysis was performed by direct DNA sequencing of the ITGB2 gene. The results revealed two novel homozygous missense mutations, c.920C>T (p.Leu307Pro) in exon 8 and c.758G>A (p.Arg253His) in exon 7, and one novel homozygous nonsense mutation, c.262C>T (p.Gln88Ter) in exon 4, in the genomic DNA of the first and second patients, respectively. Heterozygous mutations were identified in the parents of both patients, suggesting a carrier status. The patients were administered intravenous antibiotics for infections with good clinical responses. Hematopoietic stem cell transplantation could not be performed due to the unavailability of matched donors. However, a significant decline in infections was observed after antibiotic prophylaxis. Several follow-up visits were conducted for both patients. They are currently 6 years old. CONCLUSION: Molecular analysis is essential for definitive diagnosis, early treatment implementation, and prevention of LAD-1 in future pregnancy.

Genotype-Phenotype Correlation of G6PD Mutations among Central Thai Children with G6PD Deficiency.

BACKGROUND: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common X-linked inherited erythroenzymopathy in Thailand. The clinical and hematological manifestations of G6PD deficiency are variable. OBJECTIVE: This study aimed to characterize the genotype-phenotype correlation of G6PD mutations in Thai pediatric patients who were followed-up in Phramongkutklao Hospital, a tertiary center in central Thailand. Material and Method. A total of 102 children including 73 males (71.6%) and 29 females (28.4%) were included in our study. Mutation analysis was performed by direct DNA sequencing of all coding exons of the G6PD gene. Ninety-one patients (89.2%) were presented with neonatal hyperbilirubinemia and 11 patients (10.8%) were presented with acute hemolytic anemia beyond the neonatal period. RESULTS: Molecular analysis of the G6PD gene in 102 G6PD-deficient Thai children identified 12 different mutations. G6PD Viangchan (871G > A) and G6PD Canton (1376G > T) were the first (46.2%) and the second (15.4%) most common identified mutations among both male and female G6PD-deficient individuals, respectively. All affected males were hemizygous for G6PD mutations and had an average G6PD level of 16.7 ± 11.5 (3-76) IU/ml.RBC. Majority of female patients (27 in 29, 93.1%) were heterozygous for G6PD mutations and had an average G6PD level of 133.6 ± 43.4 (9-195) IU/ml.RBC. Two female patients (6.9%) were either homozygous or compound heterozygous for the mutations and had G6PD level in the affected male range (35 and 10 IU/ml.RBC). Only 1 in 27 heterozygous females (3.7%) had G6PD level in the affected male range (9 IU/ml.RBC) which is possibly explained by nonrandom X-chromosome inactivation. The correlation of genotypes, G6PD levels, and clinical phenotypes was not demonstrated in our study in which all of the included G6PD-deficient patients were presented with neonatal hyperbilirubinemia and acute hemolytic anemia, since the genotype-phenotype correlation is normally demonstrated in chronic nonspherocytic hemolytic anemia (CNSHA) G6PD-deficient individuals. CONCLUSION: This study characterizes the molecular heterogeneity of G6PD variants causing G6PD deficiency in Thai children. Our study demonstrated the efficiency of direct DNA sequencing which can identify 12 missense mutations in Thai children.

ITPA:c.94C>A and NUDT15:c.415C>T Polymorphisms and Their Relation to Mercaptopurine-Related Myelotoxicity in Childhood Leukemia in Thailand.

BACKGROUND: Mercaptopurine is a key agent in childhood leukemia treatment. Genetic polymorphism in the genes involving thiopurine metabolisms is related to 6-MP related toxicity. OBJECTIVE: This study aimed to determine the prevalence of ITPA:c.94C>A and NUDT15:c.415C>T polymorphisms among Thai children diagnosed with leukemia and their association with mercaptopurine-related myelotoxicity. METHODS: Patients and survivors with a diagnosis of leukemia treated with mercaptopurine-containing chemotherapy regimens were enrolled. Clinical data and laboratory parameters during treatment as well as ITPA:c.94C>A and NUDT15:c.415C>T genotypes were analyzed. RESULTS: In all, 99 patients with acute leukemia or survivors were enrolled in the study. The prevalences of ITPA:c.94C>A, NUDT15:c.415C>T, and co-occurrence of ITPA:c.94C>A and NUDT15:c.415C>T polymorphisms were 34, 17, and 4%, respectively. Numbers of absolute neutrophil count (ANC) and platelet count significantly decreased among patients carrying NUDT15:c.415C>T compared with NUDT15 wild type patients with p-values<0.001 and 0.019, respectively. The differences were not observed among patients carrying ITPA:c.94C>A compared with ITPA wild type patients. According to multivariate GEE, NUDT15:c.415C>T and co-occurrence of ITPA:c.94C>A and NUDT15:c.415C>T had a significant negative effect on ANC during treatment (coefficient: -463.81; CI: -778.53, -149.09; p-value=0.004 and coefficient: -527.56; CI: -1045.65, -9.48; p-value=0.046). No significant effect of ITPA:c.94C>A on ANC during treatment was observed. CONCLUSION: ITPA:c.94C>A and NUDT15:c.415C>T polymorphisms are common among Thai children with leukemia. A strong association with mercaptopurine-related myelotoxicity was observed among patients carrying either NUDT15:c.415C>T alone or combined with ITPA:c.94C>A.

A First Case Report of Subependymoma in PTPN11 Mutation-Associated Noonan Syndrome.

Noonan syndrome (NS) is an autosomal dominant disorder in some cases caused by PTPN11 mutations. Since somatic mutations in PTPN11 are seen in several tumor types, NS which causes germline PTPN11 mutations are also increase the risk of hematologic malignancies and brain solid tumors. However, the report of brain tumors in Noonan syndrome remains rather rare. Here, we report the first case of an 11-year-old Thai boy with Noonan syndrome who presented with symptoms related to hydrocephalus secondary to subependymoma in the fourth ventricle, and PTPN11 mutation was identified in this patient.

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.

Genotype-phenotype correlation among beta-thalassemia and beta-thalassemia/HbE disease in Thai children: predictable clinical spectrum using genotypic analysis.

INTRODUCTION: Beta-thalassemia is a group of inherited hemolytic anemias and one of the most common genetic disorders in Thailand. The clinical spectrum of beta-thalassemia disease ranges from mild to severe clinical symptoms including mild beta-thalassemia intermedia (TI) and severe beta-thalassemia major (TM). OBJECTIVE: This study aimed to determine the correlation between beta-globin gene (HBB) mutations and their phenotypic manifestations by evaluating patients' clinical characteristics, transfusion requirements, growth and hematologic parameters, and hemoglobin typing among pediatric patients treated at Phramongkutklao Hospital. MATERIALS AND METHODS: Seventy beta-thalassemia patients, including 63 with beta-thalassemia/hemoglobin E (HbE) and 7 with either homozygous or compound heterozygous beta-thalassemia, were enrolled in this study. Their clinical presentation, growth parameters and laboratory findings were reviewed and analyzed. The mean follow-up time was 10.52±5.62 years. Mutation analysis in each individual was performed using multiplex amplification refractory mutation system (M-ARMS), direct DNA sequencing of beta-globin gene and gap PCR for 3.4 kb deletion detection. RESULTS: All 7 homozygous and compound heterozygous beta-thalassemia patients were classified in TM. Among 63 patients with beta-thalassemia/HbE, 58 were classified in TM and 4 were classified in TI. Mean age at diagnosis was 0.8±0.49 years for homozygous or compound heterozygous beta-thalassemia and 3.43±3.5 years for beta-thalassemia/HbE. The most common HBB mutation was HBB:c.126_129delCTTT [codon 41/42 (-TCTT)] found in 34 alleles (48.6%). The height for age was also lower in homozygous beta-thalassemia patients (<3rd percentile) compared to compound heterozygous beta-thalassemia patients (25-50th percentile). CONCLUSION: This study revealed a genotype-phenotype correlation of the most prevalent beta-thalassemia in Thai children using diagnostic capacity in genotypic analysis of HBB mutation. Our findings can provide a better prediction of clinical manifestation and severity by early identification of the type of the HBB mutations.

X-Linked Chronic Granulomatous Disease: Initial Presentation with Intracranial Hemorrhage from Vitamin K Deficiency in Infant.

Vitamin K deficiency bleeding (VKDB) is a life-threatening condition and can be found in children as early as neonatal period with early onset intracranial hemorrhage (ICH). Here, we reported a 1-year-old boy who initially presented with intracranial hemorrhage secondary to vitamin K deficiency since 3 months of age and later found to have XL-CGD which was complicated by malabsorption due to severe vaccine-associated mycobacterial disease.

Clinical and molecular genetic features of Hb H and AE Bart's diseases in central Thai children.

BACKGROUND: α-Thalassemia, one of the major thalassemia types in Thailand, is caused by either deletion or non-deletional mutation of one or both α-globin genes. Inactivation of three α-globin genes causes hemoglobin H (Hb H) disease, and the combination of Hb H disease with heterozygous hemoglobin E (Hb E) results in AE Bart's disease. OBJECTIVE: This study aimed to characterize the clinical and hematological manifestations of 76 pediatric patients with Hb H and AE Bart's diseases treated at Phramongkutklao Hospital, a tertiary care center for thalassemia patients in central Thailand. PATIENTS AND METHODS: Seventy-six unrelated pediatric patients, 58 patients with Hb H disease and 18 patients with AE Bart's disease, were enrolled in this study. Their clinical presentations, transfusion requirement, laboratory findings, and mutation analysis were retrospectively reviewed and analyzed. RESULTS: A total of 76 pediatric patients with Hb H and AE Bart's diseases who mainly lived in central Thailand were included in this study. The clinical severities of patients with non-deletional mutations were more severe than those with deletional mutations. Eighty-six percent of patients with non-deletional AE Bart's disease required more blood transfusion compared to 12.5% of patients with deletional AE Bart's disease. Non-deletional AE Bart's disease also had a history of urgent blood transfusion with the average of 6±0.9 times compared to 1±0.3 times in patients with deletional Hb H disease. The difference was statistically significant. CONCLUSION: This study revealed the differences in clinical spectrum between patients with Hb H disease and those with AE Bart's disease in central Thailand. The differentiation of α-thalassemia is essential for appropriate management of patients. The molecular diagnosis is useful for diagnostic confirmation and genotype-phenotype correlation.

Genotype and phenotype correlation in intracranial hemorrhage in neonatal factor VII deficiency among Thai children.

Congenital factor VII (FVII) deficiency is a rare inherited coagulopathy. The clinical manifestations and clinical findings vary widely, ranging from asymptomatic to life-threatening bleeding, including intracranial hemorrhage (ICH), with prolonged prothrombin time, normal partial thromboplastin time and normal platelet counts, which are confirmed by the low level of FVII assay. Treatment consists of fresh frozen plasma (FFP), prothrombin complex concentrates (PCCs), and recombinant activated FVII to treat bleeding and prophylactic therapy. Here, we report four patients with FVII levels <5% (severe type) who presented ICH during the neonatal period. The IVS6+1G>T was the most common (50%) mutation identified in our study, followed by the K376X nonsense mutation (37.5%). In our study, we found that genetic information affected the severity of congenital FVII deficiency with ICH.

Galactosemia in Thai patient at Phramongkutklao Hospital: a case report.

Galactosemia is a rare autosomal recessive disorder of galactose metabolism, which occurs as a consequence of a deficiency of one of these three enzymes: galactokinase, galactose-1-phosphate uridyltransferase, and uridine diphosphate galactose-4-epimerase, leading to elevated level of galactose and its metabolites in blood. The presented case was a 2-month-old, Thai female infant with persistent cholestatic jaundice, bilateral posterior subcapsular cataracts, and hepatomegaly. Laboratory investigations showed slightly elevated serum aminotransferase, and increased urinary excretion of galactose, galactitol and galactonate (by urine gas chromatography/mass spectrometry). These findings indicated an error in galactose metabolism. Soy-based formula was introduced to the patient. Clinical and laboratory results were improved after a few months of treatment. Genetic counseling was provided to the family for 25% of recurrence risk. Prenatal diagnosis is not established in Thailand.

Homocystinuria in Thai patient--Phramongkutklao Hospital experience.

Homocystinuria is a rare autosomal recessive disorder of amino acid metabolism. Classic (type I) homocystinuria is the most common type and occurs as a consequence of a deficiency of cystathionine-b-synthase, producing increased blood and urine homocysteine. The authors report a 15-year-old Thai male who presented with generalized tonic-clonic seizures from superior sagittal sinus thrombosis, bilateral downward subluxation of ocular lenses (ectopia lentis), Marfanoid habitus, osteoporosis, attention deficit and hyperactivity disorder. Urine metabolic screening was positive for cyanide nitroprusside test. Levels of plasma homocysteine and methionine were elevated. The clinical and laboratory findings in this case are consistent with the diagnosis of "type I" or "classical homocystinuria". The treatment was started with a low methionine diet, vitamin B6 or pyridoxine, folic acid, anticonvulsants, antithrombotic treatment and calcium supplementation. Genetic counseling was provided to the family with the recurrent risk of 25%. Definite diagnosis by enzyme assay or mutation analysis and also prenatal diagnosis are not established in Thailand.

Molecular analysis of beta-globin gene mutations among Thai beta-thalassemia children: results from a single center study.

BACKGROUND: Beta-thalassemia is one of the most common genetic disorders in Thailand. Clinical phenotype ranges from silent carrier to clinically manifested conditions including severe beta-thalassemia major and mild beta-thalassemia intermedia. OBJECTIVE: This study aimed to characterize the spectrum of beta-globin gene mutations in pediatric patients who were followed-up in Phramongkutklao Hospital. PATIENTS AND METHODS: Eighty unrelated beta-thalassemia patients were enrolled in this study including 57 with beta-thalassemia/hemoglobin E, eight with homozygous beta-thalassemia, and 15 with heterozygous beta-thalassemia. Mutation analysis was performed by multiplex amplification refractory mutation system (M-ARMS), direct DNA sequencing of beta-globin gene, and gap polymerase chain reaction for 3.4 kb deletion detection, respectively. RESULTS: A total of 13 different beta-thalassemia mutations were identified among 88 alleles. The most common mutation was codon 41/42 (-TCTT) (37.5%), followed by codon 17 (A>T) (26.1%), IVS-I-5 (G>C) (8%), IVS-II-654 (C>T) (6.8%), IVS-I-1 (G>T) (4.5%), and codon 71/72 (+A) (2.3%), and all these six common mutations (85.2%) were detected by M-ARMS. Six uncommon mutations (10.2%) were identified by DNA sequencing including 4.5% for codon 35 (C>A) and 1.1% initiation codon mutation (ATG>AGG), codon 15 (G>A), codon 19 (A>G), codon 27/28 (+C), and codon 123/124/125 (-ACCCCACC), respectively. The 3.4 kb deletion was detected at 4.5%. The most common genotype of beta-thalassemia major patients was codon 41/42 (-TCTT)/codon 26 (G>A) or beta(E) accounting for 40%. CONCLUSION: All of the beta-thalassemia alleles have been characterized by a combination of techniques including M-ARMS, DNA sequencing, and gap polymerase chain reaction for 3.4 kb deletion detection. Thirteen mutations account for 100% of the beta-thalassemia genes among the pediatric patients in our study.