串联质谱技术选择性筛查遗传代谢病高危患儿552例初步分析

目的：应用串联质谱（tandem mass spectrometry, MS/MS）技术进行遗传代谢病（IEM）高危儿筛查,初步了解我国 IEM 的发病种类和阳性率,为其有效防治提供科学依据。方法：利用MS/MS技术对在河北省石家庄市8所省、市级医院就医的552例可疑 IEM 患儿的血液样本进行 IEM 筛查。结果：发现阳性患儿64例,阳性率为11.6%。其中甲基丙二酸血症或丙酸血症33例,苯丙酮尿症2例,肉碱棕榈酰转移酶缺乏Ⅰ型3例,长链酰基辅酶 A 脱氢酶缺乏症1例,中链酰基辅酶A脱氢酶缺乏症2例,枫糖尿症6例,短链酰基辅酶A脱氢酶缺乏症2例,戊二酸血症Ⅰ型2例,异戊酸血症2例,同型胱氨酸尿症2例,肉碱缺乏症4例,酪氨酸血症1例,精氨酸琥珀酸尿症1例,瓜氨酸血症2例,精氨酸血症1例。结论：MS/MS技术是筛查诊断IEM的有效工具。     

遗传性果糖不耐受症

遗传性果糖不耐受症（HFI）是一种罕见的、由于先天性醛缩酶B缺陷导致的果糖代谢病。为常染色体隐性遗传性疾病。特征是摄取果糖、蔗糖或山梨醇后发生严重的低血糖。若不及时终止此类食物，会导致肝肾功能损伤及生长发育障碍。本病诊断比较困难，治疗主要以对症治疗和饮食控制为主。本文就遗传性果糖不耐受症的临床生化特征、诊治方法及醛缩酶B损伤的分子学基础进行综述，为临床早期发现、早期诊断、早期治疗遗传性果糖不耐受症提供参考。     

Next-generation sequencing for inborn errors of immunity

Inborn errors of immunity (IEIs) include several hundred gene defects affecting various components of the immune system. As with other constitutional disorders, next-generation sequencing (NGS) is a powerful tool for the diagnosis of these diseases. While NGS can provide molecular confirmation of disease in a patient with a suspected or classic phenotype, it can also identify new molecular defects of the immune system, expand gene-disease phenotypes, clarify mechanism of disease, pattern of inheritance or identify new gene-disease associations. Multiple clinical specialties are involved in the diagnosis and management of patients with IEI, and most have no formal genetic training or expertise. To effectively utilize NGS tools and data in clinical practice, it is relevant and pragmatic to obtain a modicum of knowledge about genetic terminology, the variety of platforms and tools available for high-throughput genomic analysis, the interpretation and implementation of such data in clinical practice. There is considerable variability not only in the technologies and analytical tools used for NGS but in the bioinformatics approach to variant identification and interpretation. The ability to provide a molecular basis for disease has the potential to alter therapeutic management and longer-term treatment of the disease, including developing personalized approaches with molecularly targeted therapies. This review is intended for the clinical specialist or diagnostic immunologist who works in the area of inborn errors of immunity, and provides an overview of the need for genetic testing in these patients (the “why” aspect), the various technologies and analytical approaches, bioinformatics tools, resources, and challenges (the “how” aspect), and the clinical evidence for identifying which patients might be best served by such testing (the “when” aspect).     

Progressive cardiac failure following orthotopic liver transplantation for type IV glycogenosis

Orthotopic liver transplantation (OLT) has been proposed to treat patients with type IV glycogenosis because of early progressive cirrhosis. Reports have shown absence of disease progression in other organs after OLT and even regression of cardiac amylopectin infiltration in one case. We describe a 15-month-old child in whom a liver transplant was performed for type IV glycogenosis. There were no clinical signs of extrahepatic disease before OLT. Nine months later, the patient developed progressive cardiac insufficiency and died from cardiac failure. Because of massive amylopectin deposits, decreased myofibrils in cardiac cells, and exclusion of other causes of cardiac failure, death was attributed to amylopectinosis. Our observation contrasts with the Pittsburgh experience and suggests that cardiac amylopectionosis may progress after OLT.     

Inter-laboratory quality control in neonatal screening for inborn errors of metabolism

Screening of neonates for inborn errors of metabolism has been carried out on a national level since 1969 in the Federal Republic of Germany. To raise the reliability of these routine investigations, we introduced an external quality control in March 1982. Every 2 months ten filter paper samples were sent to the screening centres in West Germany. Some of these samples have a normal and others a slightly raised content of phenylalanine, leucine, methionine and galactose. The success of this external quality control is appraised on the basis of the number of false negative results. In the course of time, screening centres in France, Israel, Italy, Japan, Switzerland, Taiwan, Turkey and Yugoslavia have also practicipated in these inter-laboratory quality controls.Abbreviations QC quality control - BIA bacterial inhibition assay - HPLC high pressure liquid chromatography     

Seven years of experience with selective screening for organic acidurias

Between 1975 and 1981 nearly 9000 patients with suspected inherited metabolic diseases were investigated by a selective screening procedure including, apart from simple tests for ketone bodies, sugars and SH-containing compounds, high voltage electrophoresis of amino acids as well as gas liquid chromatography and gas liquid chromatography-mass spectrometry of the organic acids. Fifty-two cases with 18 different inborn errors of metabolism were detected. The effectivity index was calculated to be 0.6% or 1 case in about 170 requests. From the presented and from already existing data in the literature the overall incidences for all organic acidurias together and for propionic acidemia separately were appraized to be 1:10000 and 1:50000, respectively. About half of the patients diagnosed by this screening may benefit from the diagnosis.     

In vitro metabolism of a nitroderivative of acetylsalicylic acid (NCX4016) by rat liver: LC and LC-MS studies

The metabolism of a nitroderivative of acetylsalicylic acid, benzoic acid, 2-(acetyloxy)-3-[(nitrooxy)methyl]phenyl ester (NCX4016), the lead compound of a new class of NO-releasing non steroidal-antiinflammatory drugs has been studied in vitro in rat liver subcellular fractions (S 9000xg, microsomes, cytosol). Samples were extracted with CH3CN (2 vol.) containing 1% H3PO4 (2 M), vortexed for 3 min and then centrifuged for 5 min at 5000 rpm. Supernatants were diluted with 0.02 M phosphoric acid and analysed by reverse-phase LC. Linearity of calibration for NCX4016 and metabolites was observed over the range 0.25-50 microg/ml with coefficients of determination greater than 0.9996. Extraction efficiency from spiked liver samples ranged from 85 to 95% for all the analytes. In the S 9000xg fraction, NCX4016 undergoes rapid metabolization, with the formation of salicylic acid (SA) and [3-(nitrooxymethyl)phenol] (HBN). HBN is then rapidly metabolised to 3-hydroxybenzylalcohol (HBA), and mainly to a new metabolic species, whose formation takes place specifically in the liver cell cytosol. LC-MS analysis (electrospray ionisation) of the cytosol extract in negative and positive-ion modes furnished deprotonated [M-H]- and protonated [M+H]+ molecular ions at m/z 412 and 414, respectively, accompanied by the typical clusters with sodium. MS/MS analysis in negative-ion mode, by selection and collision of the ion at m/z 412, gave a fragmentation pattern characterized by the ions at m/z 272 and 254, which allowed to assign the structure of 1-(glutathion-S-yl)methylene-3-hydroxy-benzene, a conjugated product between GSH and the benzyl carbon atom of HBN. In rat liver cytosol HBN is completely metabolised to this thioether adduct within 30 min incubation; the process is enzymatically mediated by GSH transferase and strictly dependent on GSH availability. The relevance of this new metabolic pathway in NCX4016 detoxification by rat liver is discussed.     

3-Methylglutaconic aciduria: Report on a sibship with infantile progressive encephalopathy

Choreoathetosis, spastic parapareses, dementia and optic atrophy were the main clinical features in a sibship with progressive encephalopathy of late onset. The urine contained constantly elevated amounts of 3-methylglutaric and 3-methylglutaconic acids. The identity of these metabolites was confirmed by synthesis and mass spectrometry. On leucine loading, the excretion of the metabolites was elevated.     

Inborn errors of metabolism (IEM) — an Indian perspective

The inborn errors of metabolism (IEM) constitute a diverse heterogeneous group of disorders with protean clinical manifestations presenting mainly in the pediatric population. Though individually rare, together they constitute a significant percentage of children seen in genetic and neurology clinics. This review focuses on selected IEMs and highlights those seen in the neonatal period. Data from Indian centers are presented. It also emphasizes principles of management in these difficult disorders in the context of a developing country