先天性遗传代谢病的早期诊断

目的提高儿科医生对新生儿期遗传代谢病的认识，做到早期诊断、早期治疗。方法自2003年9月至2004年9月，根据临床表现确定18名遗传代谢病高危患儿，用“滤纸片代”将采集的尿标本外寄进行气相色谱．质谱(GC／MS)分析，筛查遗传代谢病。结果18例高危儿中确诊为遗传代谢病5例，分别为戊二酸尿症Ⅱ型1例(46h，男)，鸟氨酸氨甲酰转移酶缺陷1例(66h，男)，枫糖尿病1例(8d，男)，甲基丙二酸血症1例(13d，男)，丙酸血症1例(21d，女)，并对其临床特点进行归纳总结。结论掌握新生儿遗传代谢病临床特点，对高危儿早期进行尿GC／MS分析，可以早期诊断遗传代谢病，有利于优生优育。     

Characterization of L-aminocarnitine, an inhibitor of fatty acid oxidation

The pathogenesis of hypoketotic hypoglycemia and cardiomyopathy in patients with fatty acid oxidation (FAO) disorders is still poorly understood. In vitro studies are hampered by the lack of natural mutants to asses the effect of FAO inhibition. In addition, only a few inhibitors of FAO are known. Furthermore, most inhibitors of FAO are activating ligands of peroxisome proliferator-activated receptors (PPARs). We show that l-aminocarnitine (l-AC), a carnitine analog, inhibits FAO efficiently, but does not activate PPAR. l-AC inhibits carnitine palmitoyltransferase (CPT) with different sensitivities towards CPT1 and CPT2, as well as carnitine acylcarnitine translocase (CACT). We further characterized l-AC using fibroblasts cell lines from controls and patients with different FAO defects. In these cell lines acylcarnitine profiles were determined in culture medium after loading with [U-¹³C]palmitic acid. In control fibroblasts, l-AC inhibits FAO leading to a reduction of C2-acylcarnitine and elevation of C16-acylcarnitine. In very long-chain acyl-CoA dehydrogenase (VLCAD)-deficient fibroblasts, l-AC decreased the elevated C14-acylcarnitine and increased C16-acylcarnitine. In CACT and CPT2-deficient cell lines, l-AC did not change the already elevated C16-acylcarnitine level, showing that CPT1 is not inhibited. Oxidation of pristanic acid was only partly inhibited at high l-AC concentrations, indicating minimal CACT inhibition. Therefore, we conclude that in intact cells l-AC inhibits CPT2. Combined with our observation that l-AC does not activate PPAR, we suggest that l-AC is useful to simulate a FAO defect in cells from different origin.     

经高危筛查发现的遗传性代谢病15例分析

目的：提高临床医生对非特异性临床表现的遗传性代谢病的认识,并通过实验室检查早期诊断、早期治疗,减少后遗症。方法：对2003年6月1日至2006年9月30日期间入住上海交通大学医学院附属新华医院儿内科病房的132例非特异性临床表现的高危儿,在常规进行临床生化检查的同时行血串联质谱和尿气相质谱检测。结果：132例中诊断遗传性代谢病15例（11.5%）。其中甲基丙二酸血症(MMA)6例(40％);丙酸血症2例（13.3%）;瓜氨酸血症-II型2例（13.3%）;生物素酶缺乏症1例（6.7%）;酪氨酸血症1例（6.7%）;枫糖尿病1例（6.7%）;鸟氨酸氨甲酰转移酶缺乏症1例（6.7%）;极长链酰基肉碱辅酶A脱氢酶缺乏症1例（6.7%）。结论：对非特异性临床表现疑似遗传性代谢病的高危儿应及时进行串联质谱及气相质谱检查有助于遗传性代谢病的检出。     

Safe and unsafe duration of fasting for children with MCAD deficiency

Objective To study the safe and unsafe duration of fasting in children with medium chain acyl-Coenzyme A dehydrogenase (MCAD) deficiency, the literature and the database on Dutch MCAD-deficient patients were searched for data on fasting studies in patients with MCAD deficiency.Materials and methods These data were extended with information on fasting studies performed on our patients with MCAD deficiency known in the Beatrix Children’s Hospital, UMC Groningen, The Netherlands. The data reflect considerable inter-individual variation and overlap between safe and unsafe duration of fasting.Results In six out of 35 fasting tests, symptoms were reported before hypoglycaemia was observed. Until 1 year of age, the median safe and unsafe duration of fasting was 12 hours (n=7, range 8–19 hours) and 18 hours (n=5, range 15–20 hours), respectively. After the first year of life, the median safe and unsafe duration of fasting was 18 hours (n=17, range 10–24 hours) and 20 hours (n=9, range 13–32 hours), respectively.Conclusion Therefore, to conclude, we recommend a maximum duration of fasting in children with MCAD deficiency of 8 hours between 6 months and 1 year of age, 10 hours in the second year of life and 12 hours thereafter. From this study, no conclusions can be drawn on the duration of fasting during situations of intercurrent illness, especially with fever.     

Pharmacological evidence that α-ketoisovaleric acid induces convulsions through GABAergic and glutamatergic mechanisms in rats

Neurological dysfunction is common in patients with maple syrup urine disease (MSUD). However, the mechanisms underlying the pathophysiology of this disorder are poorly known. In the present study we investigated the effect of intrastriatal administration of the α-keto acids accumulating in MSUD on the behavior of adult rats. After cannula placing, rats received unilateral intrastriatal injections of α-ketoisocaproic acid (KIC, 8 μmol), α-ketoisovaleric acid (KIV, 8 μmol), α-keto-β-methylvaleric acid (KMV, 6 μmol) or NaCl. KIV elicited clonic convulsions in a dose–response manner, whereas KIC and KMV did not induce seizure-like behavior. Convulsions provoked by KIV were prevented by intrastriatal preadministration of muscimol (46 pmol) and MK-801 (3 nmol), but not by the preadministration of DNQX (8 nmol). These results indicate that among the keto acids that accumulate in MSUD, KIV is the only metabolite capable of causing convulsions in the present animal model and indicates that KIV is an important excitatory metabolite. Moreover, the participation of GABAergic and glutamatergic NMDA mechanisms in the KIV-induced convulsant behavior is suggested, since KIV-induced convulsions are attenuated by muscimol and MK-801. The authors suggest that KIV may play an important role in the convulsions observed in MSUD, and highlight its relevance to the understanding of the pathophysiology of the neurological dysfunction of MSUD patients.     

Congenital hypopituitarism associated with hyperammonemia

Neonatal onset hypopituitarism is a life threatening but potentially treatable metabolic condition. However, in the majority of cases it can be fatal due to the metabolic disturbances. We report a newborn with profound symptomatic hypoglycemia and hyperammonemia who initially was thought to have an inborn error of metabolism (IEM). After an initial falsely reassuring magnetic resonance imaging (MRI) brain scan, further endocrine investigation eventually led to the correct diagnosis and treatment.     

Identification of five novel inactivating mutations in the human thyroid peroxidase gene by denaturing gradient gel electrophoresis

Thyroid peroxidase (TPO) is the key enzyme in the synthesis of thyroid hormones. Defects in the TPOgene are reported to be the cause of congenital hypothyroidism due to a Total Iodide Organification Defect (TIOD). This type of defect, where iodide taken up by the thyroid gland cannot be oxidized and bound to protein, is the most common hereditary inborn error causing congenital hypothyroidism in the Netherlands. Denaturing Gradient Gel Electrophoresis (DGGE) of PCR amplified genomic DNA was used to screen for mutation in the TPO gene of TIOD patients from nine apparently unrelated families, and seven different mutations were detected. Three frameshift mutations were found: a 20 bp duplication in exon 2, a 4 bp duplication in exon 8, and an insertion of a single nucleotide (C) at pos. 2505 in exon 14. In addition, four single nucleotide substitutions were identified: one single-base, mutation resulted in a premature termination codon (C → T at pos. 1708 in exon 10), two single-base substitutions changed an amino acid in highly conserved regions of the gene (Tyr → Asp in exon 9 and Glu → Lys in exon 14). The fourth single-base mutation located at the exon 10/intron 10 border altered a conserved Gly into Ser and could also affect splicing. Nine TIOD patients from five families were compound heterozygotes and six patients from four families were homozygous for one of the mentioned mutations in the TPO gene. © 1995 Wiley-Liss, Inc.     

新生儿遗传代谢病的筛查诊断及治疗进展

遗传代谢病在新生儿早期症状大多无特异性,由于累及的部位和病情轻重差异大所以极易造成误诊.孕妇在产前应对胎儿进行遗传代谢疾病的筛查诊断,降低新生儿遗传性代谢病出生缺陷率.新生儿科医生应综合评价筛查结果及时准确地做出临床诊断,以便 对遗传代谢疾病危象期患儿采取补救措施,使他们得到进一步评估及特殊治疗.该文就新生儿遗传代谢病主要的筛查诊断及治疗方法作一综述.     

Necesidades sanitarias y socioeducativas de niños con enfermedades raras de tipo metabólico y sus familias: estudio cualitativo en un hospital de tercer nivel

Introduction

Rare diseases are a challenge for public health due to the lack of information on their magnitude. These include inborn errors of metabolism. The objective of this study was to assess the quality of life and social, health, economic, and educational needs of a group of paediatric patients with inborn errors of metabolism attended to in a hospital.