A new case of short-chain acyl-CoA dehydrogenase deficiency with isolated ethylmalonic aciduria

A 28-month-old Turkish girl presented with recurrent bronchopneumonia and severe muscular hypotonia. Urinary excretion of ethylmalonic acid was persistently elevated, methylsuccinate appearing only in stress situations. Studies in cultured fibroblasts showed a deficiency of short-chain acyl-CoA dehydrogenase.     

中、短链酰基辅酶A脱氢酶缺乏症患儿临床特点分析及基因突变研究

中、短链酰基辅酶A 脱氢酶缺乏症属脂肪酸β 氧化障碍疾病,其基因突变可导致中、短链脂肪酸无法进入线粒体进行氧化供能,引起多器官功能异常。本研究对2 例临床表现为低血糖合并代谢性酸中毒的患儿进行血酰基肉碱及尿液有机酸分析,同时对患儿及其父母进行基因突变检测。家系1 患儿,男,3 d,出生后因新生儿窒息、吸奶无力、嗜睡住院治疗。血酰基肉碱谱提示中链酰基肉碱（C6~C10）升高,其中辛酰肉碱（C8）3.52 μmol/L（参考值0.02~0.2 μmol/L）;尿有机酸分析未见明显异常;Sanger 测序发现ACADM 基因7 号外显子已报道纯合突变c.580A>G（p.Asn194Asp）。家系2 患儿,女,3 个月,因咳嗽伴反复发热10 余天住院治疗。血酰基肉碱谱提示血丁酰肉碱（C4）1.66 μmol/L（参考值0.06~0.6 μmol/L）;尿有机酸分析提示乙基丙二酸55.9（参考值0~6.2）;Sanger 测序发现ACADS 基因已报道纯合突变c.625G > A（p.Gly209Ser）。研究结果提示对不明原因代谢性酸中毒及低血糖患儿应进行遗传代谢病筛查,通过家系ACADM、ACADS 基因分析,将有助于中、短链酰基辅酶A 脱氢酶缺乏症的诊断。     

Medium-chain acyl-CoA dehydrogenase deficiency

Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is an autosomal recessive disorder of fatty acid oxidation with an incidence in the UK of more than 1:10,000. The majority of patients are homozygous for a missense mutation c.985A > G. Newborn screening for this condition was implemented in England and Northern Ireland in 2009 in Scotland in 2010 and in Wales in 2012. Patients with MCADD are at risk during periods of fasting stress, particularly during intercurrent infections, of developing an encephalopathy associated with hypoketotic hypoglycaemia. These episodes can be prevented by giving high calorie drinks (the emergency regimen) during periods of illness but hospital admission is required for intravenous dextrose if the emergency regimen is not tolerated. No specific treatment is required at other times. This review highlights the pathogenesis, the presentation and management of MCADD.     

Retrospective diagnosis of medium chain acyl-CoA dehydrogenase deficiency

Abstract A male infant is reported who died suddenly and who at post-mortem had pathological evidence suggestive of a genetic defect of fatty acid β-oxidation. A specific diagnosis could not be made enzymatically because of unavailability of suitable tissue for assay. The diagnosis of medium chain acyl-CoA dehydrogenase (MCAD) deficiency was made by specific mutation analysis using the polymerase chain reaction and DNA extracted from the newborn screening card of this infant. This powerful new molecular diagnostic technique should prove to be of use in similar circumstances.     

Early diagnosis and treatment of neonatal medium-chain acyl-CoA dehydrogenase deficiency: Report of two siblings

Two siblings are reported who were syptomatic in the neonatal period. The first died suddenly at 4 days of age after regurgitating a meal. The postmortem examination showed steatosis of the liver, kidney and muscle. In the second, medium-chain acyl-CoA dehydrogenase (MCAD) deficiency was diagnosed at 3 days of age with muscular hypotonia, vomiting, hyperammonaemia and mild acidosis. Thus disorders of fatty acid oxidation should also be considered in newborns. The biochemical work up indicates that in neonates, analysis of serum medium-chain fatty acids and of acyl and free carnitine are more likely to lead to a diagnosis than determining dicarboxylic acids alone in urine. Long-term treatment was effective and monitored by the acyl/free carnitine ratio.An abstract relating the initial findings of this patient was published by Catzeflis C, Délèze G, Kuchler H, Spahr A, Schütz B, Bachmann C (1987) Helv Paediatr Acta 42:47     

短链酰基辅酶A 脱氢酶缺乏症患儿临床特点及基因变异分析

目的探讨新生儿短链酰基辅酶A脱氢酶缺乏症(SCADD)基因型与表型的关系。方法回顾分析2015年至2018年,在青岛地区296 627例新生儿中筛查发现的7例SCADD患儿的临床资料。结果研究期间初次筛查可疑阳性人数为4 864例,初筛阳性率为0.16%;经基因检测确诊7例SCADD患儿,确诊阳性率为1/42375。7例患儿中,男性4例、女性3例,基因检测发现5种已知变异、4种未知变异,分别为c.1029+89_90insC、c.1031AG、c.1157GA、c.164CT和c.989GA,c.1130CT、c.1186GA、c.445AT和c.949AG。结论 SCADD基因型与血尿串联质谱筛查结果一致,但与临床表型关系不明确,早期诊断和治疗有助改善预后。     

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??Multiple acyl-CoA dehydrogenase deficiency??also known as glutaric aciduria type??is an autosomal recessive inherited metabolic disease. It is a mitochondrial electron transport chain and fatty acid metabolism disorder caused by a defect of electron transfer flavoprotein??ETF?? or ETF dehydrogenase??ETFDH????resulting in the damage to multiple organs such as myocardia??liver??brain and skeletal muscle. The clinical diagnosis of multiple acyl-CoA dehydrogenase deficiency is difficult due to the lack of specific symptoms and signs of the patients. To make a definitive diagnosis??blood aminoacids and acylcarnitine profiles??urinary organic acids profiles and gene analysis are necessary. According to the response to riboflavin??or vitamin B2????multiple acyl-CoA dehydrogenase deficiency could be divided into riboflavin-responsive form and riboflavin-unresponsive form. The riboflavin-responsive form is usually observed in the late-onset cases with good outcome. The patients of riboflavin-unresponsive form usually have early-onset with severe diseases. Bezafibrate, L-carnitine??coenzyme Q10??sodium-D??L-3-hydroxybutyrate and low-fat die should be considered for the treatment. Some patients with riboflavin-unresponsive form show poor outcome.     

MS/MS-based newborn and family screening detects asymptomatic patients with very-long-chain acyl-CoA dehydrogenase deficiency

OBJECTIVES: To determine whether asymptomatic persons with biochemical evidence of very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency identified through expanded newborn screening with tandem mass spectometry have confirmed disease. STUDY DESIGN: We characterized 8 asymptomatic VLCAD-deficient individuals by enzyme and/or mutational analysis and compared them with clinically diagnosed, symptomatic patients with regard to mutations, enzyme activity, phenotype, and age of disease onset. RESULTS: VLCAD molecular analyses in 6 unrelated patients revealed the previously reported V243A mutation, associated with hepatic or myopathic phenotypes, on 7/12 alleles. All other mutations were also missense mutations. Residual VLCAD activities of 6% to 11% of normal were consistent with milder phenotypes. In these identified individuals treated prospectively with dietary modification as preventive measures, clinical symptoms did not develop during follow-up. CONCLUSIONS: MS/MS-based newborn screening correctly identifies VLCAD-deficient individuals. Based on mutational and enzymatic findings, these infants probably are at risk of future disease. Because life-threatening metabolic derangement can occur even in otherwise mild phenotypes, we advocate universal newborn screening programs for VLCAD deficiency to detect affected patients and prevent development of metabolic crises. Longer-term follow-up is essential to define outcomes, the definite risk of future disease, and appropriate treatment recommendations.     

Hypoglycaemia and elevated urine ethylmalonic acid in a child homozygous for the short-chain acyl-CoA dehydrogenase 625G > A gene variation

The aim of this case report is to call attention to short-chain acyl-CoA dehydrogenase (SCAD) deficiency as a possible contributory factor to hypoglycaemia in childhood. We report on a previously healthy 14 mo-old Danish boy who presented with hypoglycaemia and metabolic acidosis after a few days of upper airway infection. After two days on a normal diet, he recovered clinically and biochemically. A thorough biochemical examination did not reveal the cause of the hypoglycaemia. However, the excretion of ethylmalonic acid in two morning urine samples was moderately increased, and hence the SCAD gene was screened for mutations. We found the child homozygous for the G > A SCAD gene variation at position 625.
Conclusion : In this patient, reduced function of the SCAD protein is reflected in the excretion of ethylmalonic acid, a marker of intracellular accumulation of butyryl-CoA and the cytotoxic butyric acid. Furthermore, gluconeogenesis might be compromised owing to lack of reducing equivalents from the oxidation of short-chain fatty acids in the fasting or stressed state, thus contributing to the predisposition for fasting hypoglycaemia.     

多种酰基辅酶A脱氢酶缺乏症儿童与成人患者临床特点比较

目的比较儿童和成人多种酰基辅酶A脱氢酶缺乏症(MADD)患者的临床和实验室检查特点。方法对12例儿童和19例成人MADD患者进行常规实验室检查、血酰基肉碱谱及尿有机酸分析。对中国人电子转运黄素蛋白脱氢酶(ETFDH)基因常见突变A84T通过DNA测序方法进行筛检。结果儿童MADD患者临床表现高度异质,可表现为肌无力、肝大、低酮性低血糖、肥厚性心肌病或脑发育不良及脱髓鞘病变;而成人患者均以肌无力起病。成人和儿童MADD有肝酶和CK升高,血多种酰基肉碱升高,多数伴有二羧酸尿。儿童组3例死亡,成人组全部存活。存活患者的症状和生化指标治疗后好转或正常。A84T突变在儿童和成人患者的发生率分别为20.8%(5/24)和21%(8/38)。结论儿童与成人MADD患者的临床表现和预后存在差异,成人患者预后好;A84T突变可能与轻型相关。[临床儿科杂志,2012,30(5):446-449]     

Multiple acyl-CoA dehydrogenation deficiency (glutaric aciduria type II), congenital polycystic kidneys,and symmetric warty dysplasia of the cerebral cortex in two brothers

Two male siblings suffering from a severe form of glutaric aciduria type II were studied. One patient died within one hour after birth, the other at the age of five days. Both patients presented with respiratory distress soon after birth. They had a variety of congenital morphologic abnormalities. One patient's outstanding sweaty-feet odour on the second day of life led to organic acid analysis of urine revealing massive lactic, glutaric, and ethylmalonic aciduria along with a high excretion of various other carboxylic acids and glycine conjugates of the branched chain carboxylic acids. The pattern of metabolites in serum and urine as well as results of degradation studies with various substrates in cultured fibroblasts were consistent with a defect in multiple acyl-CoA dehydrogenation.The morphological abnormalities are presented in a subsequent paper.     

Pitfalls of neonatal screening for very-long-chain acyl-CoA dehydrogenase deficiency using tandem mass spectrometry

Neonatal screening programs for very-long-chain acyl-CoA dehydrogenase deficiency (VLCADD) have recently been implemented. We report 2 newborns with elevated C14:1-carnitine levels on day 3 of life and normal levels on days 5 to 7. Enzyme and molecular analyses confirmed VLCADD in the first patient and heterozygosity in the second patient. We conclude that the diagnosis of VLCADD can be missed by acylcarnitine analysis during anabolic conditions. An increased C14:1-carnitine level can also occur in heterozygous individuals. Elevated C14:1-carnitine level on neonatal screening warrants further diagnostic workup even if a repeat sample demonstrates normal acylcarnitine levels.     

多种酰基辅酶A脱氢酶缺乏症的诊治进展

多种酰基辅酶A脱氢酶缺乏症是一种较为常见的脂肪酸代谢紊乱,临床表现高度异质,常有呕吐、酸中毒以及脂质沉积性肌病表现,根据血多种酰基肉碱升高及尿中戊二酸等有机酸升高可明确诊断.新生儿发作型临床表现重,预后较差;核黄素治疗反应性患者给予核黄素治疗可完全纠正其临床症状及生化紊乱;核黄素无反应者应同时给予低脂、低蛋白、高碳水化合物饮食,并预防急性代谢紊乱的发作.     

Influence of valproic acid on the expression of various acyl-CoA dehydrogenases in rats

BACKGROUND: Valproic acid (2-propyl-N-pentanoic acid, VPA) causes severe hepatic dysfunction, similar to Reye's syndrome, in a small number of patients. An enhanced excretion of dicarboxylic acids by patients indicates an interference with mitochondrial beta-oxidation. We investigated the expression of various acyl-coenzyme A (acyl-CoA) dehydrogenases (ACD), which catalyze the first step of beta-oxidation in VPA-treated rats. METHODS: The control group received normal saline and the experimental group received VPA (500 mg/kg per day) by intraperitoneal injections for 7 days. Various clinical chemistry parameters in rat blood and free and total carnitine levels in plasma and tissue were determined. Mitochondria were isolated from rat liver and heart and the relative amount of each ACD protein was determined by immunoblot analysis. Total RNA was prepared from various tissues and the mRNA levels for various ACD were measured by slot-blot hybridization analysis using respective cDNA probes. RESULTS: Administration of VPA to rats caused various metabolic effects including hypoglycemia, hyperammonemia and decreased beta-hydroxybutyrate concentration. Free carnitine levels in plasma and heart were also decreased. Enzyme activities of various acyl-CoA dehydrogenases, which are involved in fatty acid oxidation, decreased moderately in heart (57-79%), and slightly in liver (78-95%). The most prominent effects were observed in mRNA levels involved in fatty acid oxidation (short-, medium- and long-chain acyl-CoA dehydrogenase). Each mRNA increased in the liver, kidney, skeletal muscle and heart to varying degrees when rats were fed ad libitum. The increase of short- and medium- chain acyl-CoA dehydrogenase mRNA in the heart were particularly large. However, 3 day starvation strongly inhibited expression of ACD in VPA-treated rats. There was an apparent decrease in the amount of ACD mRNA and proteins in VPA-treated liver. CONCLUSIONS: Valproic acid causes enhanced expression of fatty ACD mRNA, especially in the heart, by a feedback mechanism related to inhibition of beta-oxidation in rats fed ad libitum. However, it impairs the expression of ACD in the liver when there is a drastic change in nutritional state.     

极长链酰基辅酶A脱氢酶缺乏症研究进展

极长链酰基辅酶A脱氢酶缺乏症是一种较罕见的脂肪酸代谢障碍疾病,根据起病年龄和临床表现分为三型：心肌病型、肝型、肌病型。心肌病型病情重,病死率高。临床诊断可通过血串联质谱(MS/MS)检测血肉豆蔻烯酰基肉碱(C14:1)水平进行,进一步确诊可通过基因诊断、酶学分析及脂肪酸氧化流量分析。治疗上主要包括避免空腹,减少长链脂肪酸的摄入,补充中链甘油三酯等。     

The natural history of medium-chain acyl CoA dehydrogenase deficiency in the Netherlands: clinical presentation and outcome

OBJECTIVES: To describe the clinical presentation and long-term follow-up of a large cohort of patients with medium-chain acyl-CoA dehydrogenase (MCAD) deficiency. STUDY DESIGN: A nationwide, retrospective analysis of clinical presentation and follow-up in 155 Dutch patients with MCAD deficiency. RESULTS: Most patients presented between 3 months and 5.1 years of age; 13% had symptoms as neonates not exclusively related to breast-feeding. An acute presentation before the diagnosis was made resulted in a mortality of 22% (25/114), whereas 21% (19/89) developed disabilities after the diagnosis. On follow-up, a total of 44 patients reported fatigue (35%; 28/80), muscle pain (31%; 25/80), and/or reduced exercise tolerance (39%; 31/80). Cardiac evaluation in 11 adult patients revealed no abnormalities in cardiac function explaining these complaints. Children with MCAD deficiency readily become overweight. CONCLUSIONS: Mortality and morbidity were high in undiagnosed children with MCAD deficiency; establishment of the diagnosis significantly improves outcome. Strikingly, after the diagnosis and initiation of treatment, overweight and chronic complaints (fatigue, muscle pain, and reduced exercise tolerance) were prominent.     

Milder childhood form of very long-chain acyl-CoA dehydrogenase deficiency in a 6-year-old Japanese boy

We investigated the clinical and biochemical characteristics of a 6-year-old Japanese boy with very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency. He had hypoketotic hypoglycaemia, exercise- and fasting-induced lethargy, hepatomegaly and cardiomegaly. Significant laboratory findings included elevated plasma levels of creatine phosphokinase and acyl-carnitine and a fatty liver at biopsy suggesting a diagnosis of VLCAD deficiency. Conclusion The diagnosis of very long-chain acyl-CoA dehydrogenase deficiency was supported by the results of acyl-CoA dehydrogenase activity for C₈ and C₁₆ fatty acids in skin fibroblasts from the patient. Treatment with medium chain triglycerides and l-carnitine in the diet improved his hepatomegaly and cardiomegaly. Received: 17 April 2000 / Accepted: 5 July 2000     

Incidence of medium-chain acyl-CoA dehydrogenase deficiency in Canada using the Canadian Paediatric Surveillance Program: Role of newborn screening

BACKGROUND:

The incidence of medium-chain acyl-CoA dehydrogenase deficiency (MCADD) was estimated using the Canadian Paediatric Surveillance Program (CPSP) in Canada over a three-year period. Data regarding mutations associated with MCADD cases were collected wherever available.

METHODS:

Data were collected over a 36-month period using a monthly mailed questionnaire distributed through the CPSP to more than 2500 Canadian paediatricians, medical geneticists and paediatric pathologists.

RESULTS AND CONCLUSIONS:

During the three years of MCADD surveillance, 46 confirmed cases out of a total of 71 reported cases were found – an average of approximately 15 cases per year. This rate is lower than the initial estimate of approximately 30 cases per year of MCADD in Canada, based on the reported incidence of MCADD in the literature of approximately one in 10,000 to one in 20,000. All cases ascertained by newborn screening were asymptomatic. There were two deaths, both in jurisdictions without newborn screening for MCADD. The data support population-based newborn screening for MCADD.     

Frequency of 985A-to-G mutation in medium-chain acyl-CoA dehydrogenase gene among patients with sudden infant death syndrome,Reye syndrome,severe motor and intellectual disabilities and healthy newborns in Japan

The prevalence of the ⁹⁸⁵A-to-G mutation in the medium-chain acyl-CoA dehydrogenase (MCAD) gene among Japanese patients with sudden infant death syndrome, Reye syndrome, unknown fatty acid oxidation disorders and severe motor and intellectual disabilities was studied using the PCR/Nco-I method for molecular diagnosis. A frequency study of this common mutation was also conducted on blood samples and left over Guthrie cards from 329 healthy newborns in Japan. Neither heterozygotes nor homozygotes for the ⁹⁸⁵A-to-G mutation were identified among both patients and controls. The result of the present study accord with previous reports that MCAD deficiency is a common disorder in Caucasians, but quite rare among Japanese. Therefore, newborn mass-screening for MCAD deficiency using this method will not be practical in Japan. However, it still seems necessary to investigate a child with fatty acid oxidation disorder for the presence of MCAD deficiency, using both biochemical and molecular genetic methods.     

Medium-chain acyl-CoA dehydrogenase deficiency does not correlate with apparent life-threatening events and the sudden infant death syndrome: results from phenylpropionate loading tests and DNA analysis

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is the most common inherited disorder of fatty acid metabolism and typically presents in early childhood as potentially fatal hypoketotic, hypoglycaemic crisis often associated with Reye-like symptoms. Re-investigations of cases of sudden infant death syndrome (SIDS) have revealed in some instances a deficiency of MCAD, suggesting that this metabolic disorder may lead to sudden infant death without prior clinical symptoms. In the present study, we examined 142 infants who had suffered from an apparent life-threatening event (ALTE) or were otherwise considered at risk for SIDS for MCAD deficiency by phenylpropionate loading. In no case excretion of phenylpropionylglycine, the hallmark of MCAD deficiency, was increased. In contrast, 3 out of 55 children with symptoms of metabolic disorders showed increased phenylpropionylglycine excretion, and in all three cases MCAD deficiency was confirmed by DNA analysis. In addition, we investigated 142 cases of sudden unexplained child death and 100 control subjects for the A985G mutation in the MCAD gene which is associated with about 98% of enzyme deficiencies. We found one case of heterozygosity each in the patient and control group. Our data indicate that MCAD deficiency is not a major cause of ALTE and, in agreement with results from similar studies in other countries, its frequency is not increased in children who died of SIDS.