Estudo de associação genética entre fator de necrose tumoral alfa e sepse e choque séptico em pacientes pediátricos tailandeses / Genetic association study of tumor necrosis factor-alpha with sepsis and septic shock in Thai pediatric patients

OBJETIVOS: Avaliar a associação entre o polimorfismo genético do fator de necrose tumoral alfa (TNF-α) e o desenvolvimento de sepse e choque séptico em pacientes pediátricos tailandeses e investigar o impacto clínico de polimorfismos do TNF-α nessa população. MÉTODOS: Para a realização deste estudo de associação genética, foram analisados prospectivamente pacientes pediátricos (idade < 18 anos) com sepse clínica/choque séptico. Todos os dados foram coletados por especialistas em terapia intensiva pediátrica e as análises genéticas foram realizadas em um laboratório central. Um polimorfismo de nucleotídeo único [single nucleotide polymorphism (SNP)], localizado na região promotora 5' na posição -308, foi genotipado e os resultados foram associados a fenótipos clínicos. RESULTADOS: Foram investigados 167 indivíduos tailandeses, dos quais 66 eram pacientes pediátricos com sepse/choque séptico e 101 eram controles saudáveis. Curiosamente, não foi possível identificar associação entre sepse e o polimorfismo -308 (G→A), um dos principais SNPs anteriormente associado à sepse em várias populações caucasianas, visto que não houve diferença de frequência entre casos e controles. CONCLUSÕES: Neste estudo, o principal polimorfismo do TNF-α -308 não esteve associado à sepse clínica/choque séptico na população tailandesa. Essa informação é importante para futuras análises que busquem identificar a função do TNF-α como risco genético para o desenvolvimento de imunopatologia subjacente a várias doenças no continente asiático.

OBJECTIVES: To evaluate the association between the genetic polymorphism of the tumor necrosis factor-alpha (TNF-α) gene and the development of sepsis and septic shock in Thai pediatric patients and to investigate the clinical impacts of TNF-α polymorphisms in this population. METHODS: To perform this genetic association study, a prospective analysis of pediatric patients (age < 18 years) with clinical sepsis/septic shock was conducted. All clinical data were collected by pediatric intensive care experts, and genetic analyses were performed at a central laboratory. A single nucleotide polymorphism (SNP) located in the 5'-promoter region at position -308 was genotyped and the results were associated with clinical phenotypes. RESULTS: A total of 167 Thai individuals were investigated, 66 of which were pediatric patients with sepsis/septic shock and 101 were healthy controls. Interestingly, we could not identify an association between sepsis and -308 (G→A) polymorphism, which have previously been demonstrated to be a major SNP associated with sepsis in several Caucasian populations, since there was no frequency difference between cases and controls. CONCLUSIONS: In this report, the major TNF-α polymorphism (-308) was not associated with clinical sepsis/septic shock in Thais. This information will be important for future analyses to identify the role of TNF-α as a genetic risk for the development of immunopathology underlying several diseases in Asia.

Clinical and hematological phenotype of homozygous hemoglobin E: revisit of a benign condition with hidden reproductive risk.

Hemoglobin E (HbE) is one of the most prevalent beta-globin variant, which is widely distributed in Southeast Asia especially in Thailand. Homozygosity for this variant is common and may occur with iron deficiency. In order to study clinical and hematological phenotypes without the confounding effect of iron deficiency, investigations were carried out before and after iron supplementation for 2 months. The effect of G6PD deficiency and coinheritance of alpha-thalassemia in homozygous HbE were also studied. HbE homozygotes were clinically benign, never had been transfused and had no hepatosplenomegaly. Out of 76 HbE homozygotes, hematological parameters of 7 individuals with iron deficiency improved after iron supplementation. Hemoglobin analysis revealed that HbE was the main hemoglobin detected, but 12 subjects were found to have a substantial percentage of HbF, which might lead to misdiagnosis as HbE/beta-thalassemia. Both clinical and hematological phenotypes of simple homozygous HbE did not differ from those who also inherited alpha-thalassemia and/or G6PD deficiency. It is necessary to perform a comprehensive DNA analysis for alpha-thalassemia in cases of homozygous HbE when their partner is suspected of having alpha-thalassemia 1 gene.

Development of a comprehensive red blood cell enzymopathy laboratory in Thailand: the study of normal activity in eight erythroenzymes in Thais.

In order to provide a reference range for normal red blood cell enzyme activities in Thai, we analyzed data from 113 healthy non-anemic Thai people (55 males and 58 females) age 1-42 years, who all had a normal pattern of hemoglobin typing (HbA and HbA2 less than 3.5%). Hematological analysis was performed using an automated cell counter and the hemoglobin studies were carried out by low pressure liquid chromatography. Owing to a high frequency of alpha-thalassemia in Thailand, cases with an MCV < 75 fl were excluded from the study since these cases were likely to be heterozygotes for alpha0-thalassemia. Cases with reticulocytes > 2.5% were excluded from the study since reticulocytes have a higher enzyme activity than mature erythrocytes. Cases with abnormal red blood cell morphology, such as spherocytes and ovalocytes, were also excluded. These criteria were applied to select "normal" controls for our analysis. We assayed eight red blood cell enzyme activities in normal subjects: glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), pyruvate kinase (PK), hexokinase (HK), glucose phosphate isomerase (GPI), phosphofructokinase (PFK), aldolase (ALD) and phosphoglycerate kinase (PGK). The mean normal ranges (+/- SD) for G6PD, 6PGD, PK, HK, GPI, PFK, ALD and PGK were 12.7 (+/-2.2), 10.7 (+/-1.3), 18.5 (+/-4.0), 1.5 (+/-0.4), 80.5 (+/-11.8), 11.8 (+/-2.1), 4.5 (+/-1.6) and 370 (+/-43) IU/gHb, respectively. Age-dependent differences for the reference values for these enzyme activities were summarized. All red blood cell enzyme activities were highest during the early childhood period and slightly lower in the adult period. These values will be of clinically useful for future reference.

Successful treatment of disseminated BCG infection in a SCID patient with granulocyte colony stimulating factor.

Severe combined immunodeficiencies (SCID) are disorders with impairment of humoral and cellular immune functions. The prognosis of disseminated bacillus Calmette-Guérin (BCG) infection in immunocompromised host is unfavorable since response to standard therapy is poor. We report a successful treatment of disseminated BCG infection with granulocyte colony stimulating factor (G-CSF) in a patient with severe combined immunodeficiency. The patient failed to response to intensive anti-tuberculous (anti-TB) therapy. After 2 months of G-CSF, in addition to anti-TB treatment, the clinical signs of disseminated BCG infection were improved. Since serious BCG infections in SCID are not uncommon in developing countries, where BCG vaccination is mandatory to all newborns, the combination of G-CSF and anti-TB drugs should be considered in immunocompromised patients with protracted mycobacterial infection.

Clinical phenotypes and molecular diagnosis in a hitherto interaction of Hb E/beta thalassemia syndrome (beta(E)/beta(-31), (A -->G)).

Molecular identification of affected alleles in the index family with rare mutation(s) and/or interaction(s) is an important prerequisite toward a proper genetic counseling. In Thailand, where more than 30% of the populations are heterozygotes for either alpha or beta thalassemia mutation(s). More than 60 different thalassemia syndromes resulting from the interactions of these heterogeneous alleles have been observed. The majority of patients in the hospital based-study are compound heterozygotes for beta thalassemia alleles and another hemoglobinopathy namely Hb E, highly prevalent in Thailand, gave rise to Hb E/beta thalassemia syndrome. The phenotypes of these syndromes vary from asymptomatic individual to a very severe phenotype mimic that of beta thalassemia major. In this report, we describe a three-year-old Thai girl presenting with mild hypochromic microcytic anemia since birth. She was born prematurely and developed anemia within the first week of life. The cause of anemia was suspected to result from prematurity and low intrauterine iron storage, however hypochromic anemia did not resolve after a three-month of iron supplement therapy. Subsequent studies indicated that the patient had Hb E/beta thalassemia disease and the molecular study revealed that the patient was a compound heterozygote for Hb E and a rare beta thalassemia mutation (beta(-31), A --> G). This hitherto genotype results in a relatively mild clinical symptom since the patient's baseline Hb values were around 9-10 g/dL with normal weight and height development during the follow-up period.

Hematological parameters and red blood cell indices in healthy Thai children: a revision for 2005.

In order to provide a reference range for hematological parameters and red blood cells indices in Thai children, we analyzed data from 395 healthy non-anemic Thai children age from 1-16 years old, who all had normal pattern of hemoglobin typing (Hb A and Hb A2 less than 3.5%). Hematological analysis was performed using an automated cell counter and the hemoglobin studies were carried out by electrophoresis and liquid chromatography. Owing to a high frequency of a thalassemia in Thailand, cases with MCV < 75 fL has been excluded from the study since these cases were likely to be heterozygotes for alpha0 thalassemia. These criterions were applied to select so-called 'normal' controls for our analysis. Relatively mild microcytosis and hypochromia were observed, in particular in the first three years of age, suggesting an intrinsic immature nature of erythropiesis in the children. Age-dependent differences in the reference values for white blood cell (WBC) count and differential and platelet count were observed. Herein the hematological data and red blood cell indices were summarized according to ages and these will be of clinically useful for the future reference.

Dengue hemorrhagic fever in patients with thalassemia.

Dengue hemorrhagic fever (DHF) causing by dengue viral infection is endemic in Thailand and Southeast Asian countries where thalassemias are prevalent. Thalassemic patients are also at risk to acquire dengue viral infections and to develop DHF. However, they can have different clinical manifestations and complications as well as more severity than general population requiring special awareness for proper diagnosis and management. We reported 20 thalassemic patients (10 boys and 10 girls) with DHF admitted to Department of Pediatrics, Siriraj Hospital during 1977 to 2001. Their ages ranged from 2-16 years (average 9.5 years). These cases included 5 cases of Hb H disease, 5 cases of Hb H with Hb Constant Spring (CS), 9 cases of beta-thalassemia/Hb E disease and 1 case of beta-thalassemia major. Two cases were in Grade I, 10 cases in grade II, 7 cases in Grade III and one case in grade IV severity of DHF. Though there were evidences of plasma leakage, instead of hemoconcentration, eighteen patients (90 percent) had hematocrit dropped at the range of 11-66% of the initial level. Fifteen patients (75 percent) required at least one packed red cell transfusion. Nine patients (45 percent) had mild bleeding symptoms, one of them had upper gastrointestinal hemorrhage requiring platelet concentrate transfusion. Two patients (10 percent) had serious complications including one with infection-associated hemophagocytic syndrome (IAHS) requiring intravenous immunoglobulin (IVIG) and packed red cell transfusion and the other had generalized seizure due to hyponatremia and hypotension. No mortality was observed among this group of patients. Early recognition of the DHF in thalassemic patients and appropriate packed red cell transfusion in patients with anemic symptoms is warranted to reduce morbidity and mortality in these patients.

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.

Effect of red blood cell glucose-6-phosphate dehydrogenase deficiency on patients with dengue hemorrhagic fever.

Eighty nine males aged 1-13 years diagnosed with dengue haemorrhagic fever (DHF) and admitted to the Department of Pediatrics Siriraj Hospital from March 1998 to April 2000 were included in this study. 17 cases (19.1%) had red blood cell glucose-6-phosphate dehydrogenase (G-6-PD) deficiency and 72 cases (80.9%) had normal G-6-PD enzyme activities. Most of the patients were classified as DHF grade II in severity. 3 of 17 G-6-PD deficient cases had serious complications and all of them had acute intravascular hemolysis requiring blood transfusions. One of these also had hematemesis, one had azothemia and the other one had renal failure and severe liver failure with hepatic encephalopathy. In the cases without obvious hemolytic or hepatic complications, G-6-PD deficient cases had mildly but significantly higher total birirubin and indirect bilirubin, as well as a lower hematocrit than those who had normal G-6-PD. Reticulocyte count was low during the acute phase, however, during recovery, the levels were significantly increased in both groups. In the non G-6-PD deficient group, G-6-PD enzyme levels were significantly decreased during the acute phase compared to the normal controls but rose significantly to normal levels during the recovery phase. There were no statistically significant differences in other laboratory data. All patients recovered fully from DHF. The prevalence of G-6-PD deficiency in male patients who had DHF in this study was 19.1 per cent which was higher than the prevalence in a previous study of 12 per cent in Bangkok. This may imply that G-6-PD deficient males suffer more from DHF compared to normal G-6-PD subjects.

Allele related mutation specific-polymerase chain reaction for rapid diagnosis of Hb New York (beta 113 (G15) Val-->Glu, beta(CD113 GTG-->GAG)).

Hemoglobin New York (beta 113 (G15) Val-->Glu), a beta-globin variant, was first reported in a Chinese family living in New York. Subsequently, this abnormal hemoglobin was reported in many Chinese descendants from several groups and it was also known as Hb Kaohsiung. The subtle change in alpha1beta1 contact region apart from the heme group connecting area by Val-->Glu substitution has minor changes in both the electrophoretic mobility and stability making this hemoglobin variant difficult to distinguish from Hb A using routine hemoglobin analysis. The authors described a case of heterozygosity of Hb New York diagnosed by a molecular technique and revealed a mutation in beta(CD113 GTG-->GAG). A novel Allele Related Mutation Specific-Polymerase Chain Reaction (ARMS-PCR) for rapid diagnosis of this mutation has been proposed.