肉碱棕榈酰转移酶Ⅱ缺乏症家系CPT2基因突变分析及产前诊断

分析肉碱棕榈酰转移酶Ⅱ（CPTⅡ）缺乏症患儿及其父母CPT2基因突变类型,为家系成员提供遗传咨询及产前诊断。先证者,女,于3个月时发烧8 h入院,血液酯酰肉碱谱分析显示棕榈酰肉碱显著增高,提示CPTⅡ缺乏症。收集患儿临床资料,采集患儿和父母外周血,提取基因组DNA,应用直接测序法进行CPT2基因5个外显子编码区及与外显子交界的部分内含子区域进行测序。患儿母亲于妊娠中期采取羊水,分取羊水细胞进行CPT2基因突变分析。Sanger测序发现先证者CPT2基因存在两个已知致病突变c.886C > T（p.R296X）和c.1148T > A（p.F383Y）,突变来自父母双方。母亲第二胎羊水细胞CPT2基因存在c.886C > T（p.R296X）,为致病基因携带者。胎儿出生后血液酯酰肉碱谱正常,发育正常。通过家系CPT2基因分析,证实了先证者死因为CPTⅡ缺乏症,在突变明确的前提下,成功地进行了下一胎同胞的产前诊断,为该家庭提供帮助。     

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。     

中链酰基辅酶A脱氢酶缺乏症新生儿筛查及随访研究

目的 探讨中链酰基辅酶A脱氢酶缺乏症（MCADD）中国人群流行病学特征、表型、基因型及预后。方法 回顾性分析2009年1月至2018年6月期间经高效液相色谱串联质谱（HPLC-MS/MS）筛查并结合基因检测诊断为MCADD的新生儿资料。结果 2 674 835例接受筛查的新生儿中诊断MCADD的12例（1/222 902）。其中10例接受基因检测,发现ACADM基因16个突变位点的13种突变类型：7种为已报道突变（p.T150Rfs^*4、p.M1V、p.R206C、p.R294T、p.G310R、p.M328V、p.G362E）;5种新突变（p.N194D、p.A324P、p.N366S、c.118+3A > G、c.387+1del G）和1例11号外显子缺失,以p.T150Rfs^*4最常见（4/16）。ACADM基因突变位点检出率80%。未见表型-基因型相关性。确诊后给予饮食指导及对症治疗,随访4~82个月期间未见急性代谢失衡发作,除1例合并脑发育不良外均预后良好。结论 MCADD在中国南方人群相对罕见;p.T150Rfs^*4为中国人群热点突变;筛查阳性的病例建议联合辛酰基肉碱检测及基因判断。     

3-羟基-3甲基戊二酰辅酶A裂解酶缺乏症临床特点及基因变异分析

目的 了解3-羟基-3甲基戊二酰辅酶A裂解酶缺乏症的临床特点及基因变异情况。方法 分析6例3-羟基-3甲基戊二酰辅酶A裂解酶缺乏症患儿的临床资料及基因检测结果。结果 6例患儿，男性3例，女性3例。1例家族史阳性。3例患儿当地医院行新生儿筛查提示该疾病，2例患儿为发病后临床诊断，1例患儿至今未发病。5例患儿发病年龄10天～5岁。初诊年龄为1个月～7岁，发病时均有不同程度的代谢危象、低血糖和高乳酸血症等表现。2例患儿死亡。血串联质谱显示3-羟基异戊酰肉碱升高，部分患儿伴有己二酰肉碱升高；尿有机酸分析提示3-羟基-3-甲基戊二酸显著升高，伴3-甲基戊烯二酸、3-羟基异戊酸等增高。4例患儿基因检测均发现HMGCL基因变异：2例c.122G>A(p.R41Q)纯合；1例c.697C>T(p.H233Y)纯合；1例c.145-2A>G和c.590G>A(p.C197Y)复合杂合。其中，c.697C>T(p.H 233Y)、c.145-2A>G和c.590G>A(p.C197Y)变异均为首次报道，蛋白结构预测均为可能有害，ACMG评级为可能致病。另2例患儿未...     

原发性肉碱缺乏症与猝死两家系分析

目的：探讨两个原发性肉碱缺乏症家系的临床特点及基因突变位点的检测,分析其中3例患儿的猝死原因。方法回顾性分析两个原发性肉碱缺乏症家系的临床资料,分别对两个家系的先证者行血氨、血乳酸、肝酶、心肌酶测定,血酰基肉碱分析和尿有机酸分析,提示原发性肉碱缺乏症可能,进一步对两家系成员行SLC22A5基因测序分析。结果两个家系先证者游离肉碱及多种酰基肉碱明显低下,死亡患儿在发病前均有发热、呕吐、嗜睡等表现。家系Ⅰ的先证者为c.760C>T( p. R254X)纯合突变,家庭其他成员均为c.760C>T杂合子。患儿死于严重心律失常及心肌病。尸体解剖病理提示部分心肌纤维断裂或呈波浪状排列、肝细胞弥漫性脂肪变性、部分肺泡腔可见中性粒细胞浸润。家系Ⅱ中2例死亡患儿疑似“病毒性心肌炎”。先证者并未发病,但已出现轻微心肌肥厚、血氨增高等,经左卡尼汀治疗后各项指标恢复正常,存在c.760C>T和c.844dupC(p. R282fs)两个杂合突变,分别遗传自父母。结论原发性肉碱缺乏症患儿,在疾病的缓解期无特殊表现,发病急且病情迅速恶化,甚至死亡。家系Ⅰ先证者因全身肉碱缺乏而发生心源性猝死。 c.760C>T纯合突变、c.760C>T和c.844dupC复合杂合突变可能分别是家系Ⅰ和家系Ⅱ发病的分子基础。早期诊断、规范治疗是决定远期预后的关键。     

原发性肉碱缺乏症的筛查与患者SLC22A5基因突变分析北大核心CSCD

目的探讨原发性肉碱缺乏症（pfimary camitine deficiency,PCD）患者的临床特点和SLC22A5基因突变情况。方法利用液相（色谱）串联质谱技术对徐州市2015年9月至2017年12月出生的210908例新生儿和576例临床遗传代谢病疑似患儿进行游离肉碱及酰基肉碱检测,对游离肉碱降低的患儿进行SLC22A5基因突变分析以确诊。对确诊患儿的临床表现、生化特点、基因特点及治疗预后进行分析,并采用配对样本t检验对患儿治疗前后的生化指标进行比较。结果共确诊10例PCD患儿（其中9例来自新生儿筛查,1例来自临床患儿）和7例母源性肉碱缺乏症患者,口服左卡尼汀治疗后血游离肉碱和其他酰基肉碱水平恢复正常。1例来自临床患儿的临床症状消失,16例来自新生儿筛查的患儿无任何临床症状,生长发育正常。17例患儿均进行基因突变检测,共检出10种突变类型,分别为c．1400C〉G、c．1462C〉T、c．797C〉T、c．95A〉G、c．92C〉T、c．1093A〉C、c．761G〉A、c．865C〉T、c．428C〉T、c．1195C〉T,其中c．1093A〉C和c．92C〉T为新突变,c．1400C〉G为最常见的突变类型。结论液相（色谱）串联质谱技术可筛查出新生儿及母源性肉碱缺乏症患者,徐州地区c．1400C〉G突变出现频率最高,早期治疗预后良好。     

新生儿全血细胞减少伴代谢异常

患儿,男,9d,急性起病,表现为咳嗽、气促、喂养困难、嗜睡、昏迷。辅助检查提示肺部感染、严重代谢性酸中毒、高血糖、高血氨、血象三系减少。为查明病因,进行了血液酯酰肉碱谱及尿液有机酸分析及基因诊断。结果发现：血异戊酰肉碱及尿异戊酰甘氨酸和3-羟基异戊酸显著升高,游离肉碱降低,提示异戊酸血症 （IVA）;基因检测提示第12号外显子纯合突变c.1208A > G （p.Tyr403Cys）,父母为杂合突变携带者。经低亮氨酸饮食、左卡尼汀等治疗后症状稍改善,但1周后患儿死亡。新生儿肺炎是新生儿常见感染,但可能是遗传代谢病患儿的诱发因素,因此对于肺炎起病的伴有难以解释的代谢异常患儿,应进行遗传代谢性疾病筛查。     

中链酰基辅酶A脱氢酶缺乏症1例肝脏病理分析及基因检测

目的探讨中链酰基辅酶A脱氢酶缺乏症(MCADD)的诊断和治疗。方法回顾性分析1例MCADD患儿的临床表现、实验室检查以及基因检测结果,并复习相关文献。结果 3岁男性患儿,有一过性低血糖、高氨血症、肝功能损伤;血串联质谱分析提示辛酰肉碱、多种酰基肉碱增高,尿气相色谱质谱分析正常;基因检查示酰基辅酶A脱氢酶基因(acyl-Coenzyme A dehydrogenase,ACADM)c.572GA p.(Trp191*)纯合突变;肝脏病理提示肝细胞轻度损害,炎症程度2级,纤维化程度1级。给予高碳水化合物、高蛋白、低脂肪饮食,积极护肝、降酶、补充肉碱等治疗后患儿肝功能恢复正常。结论血串联质谱分析及基因检测可确诊MCADD,确诊后应积极补充高能量营养物质、肉碱,以预防疾病发作和病情进展。     

全羧化酶合成酶缺乏症导致的婴儿死亡1例报告北大核心CSCD

回顾性分析2020年5月包头市第四医院收治的1例确诊为全羧化酶合成酶缺乏症的死亡婴儿的临床和分子遗传学资料。患儿男,2月龄29 d,因“喉中痰鸣5 d,抽搐1 d,昏迷半天”入院。反应差,代谢性酸中毒难以纠正,经积极治疗2 d后病情仍进一步加重,自动出院,返家当日死亡。血氨基酸及及酰基肉碱分析示3-羟基异戊酰肉碱及丙酰肉碱增高。尿液有机酸分析示3-羟基丙酸、丙酰甘氨酸、甲基巴豆酰甘氨酸、甲基枸橼酸升高。采用全外显子组测序示HLCS存在c.1522C>T(p.R508W)/c.782delG(p.G260V)复合杂合突变,经Sanger家系验证突变来源于父母。HLCS缺乏症临床表现不典型,对于重症肺炎合并癫痫及难以纠正的代谢性酸中毒患儿,应考虑HLCS缺乏症可能,及时行代谢筛查及基因分析确诊。     

原发性肉碱缺乏症临床和基因突变特点及1例产前诊断研究

目的探讨原发性肉碱缺乏症的临床特点、基因突变及产前基因诊断。方法回顾分析8例原发性肉碱缺乏症患儿的临床资料、基因突变分析结果,以及1例患儿母亲再次妊娠羊水细胞产前基因诊断结果。结果 6例男性、2例女性患儿,发病年龄5个月～3岁,以呕吐、腹泻、抽搐、意识障碍等就诊。血浆游离肉碱均降低(0.67～4.184μmol/L),血红蛋白均偏低(67～110 g/L)。6例患儿存在不同程度肝功能和心肌酶异常,6例血氨升高,2例血糖降低。心脏彩超示心肌病4例。心电图异常2例。SLC22A5基因共检出6种突变,分别为c.760CT(p.Arg254X)、c.1400CG(p.Ser467Cys)c. 844 dupC(p.R 282 PfsX 10)、IVS 2+1 GT、c. 3 GT(p.Met 1 Ile)、c. 338 GA(p.Cys 113 Tyr)。1例患儿染色体微阵列分析显示5q23.3q31.3区域存在大片段杂合性缺失。1例患儿母亲再次妊娠18周时的羊水细胞检出c.760CT杂合突变,提示胎儿为携带者,出生后外周血SLC22A5基因存在一个c.760CT杂合突变位点,血浆游离肉碱浓度无异常。除1例患儿猝死外,其余7例经左卡尼汀治疗有效,随访中。结论原发性肉碱缺乏症患儿起病急,心肌、肝脏损伤尤为突出,左卡尼汀治疗效果肯定。SLC22A5基因分析可作为确诊和产前诊断的依据。     

The A985 to G mutation of the medium-chain acyl-CoA dehydrogenase gene and sudden infant death syndrome in Normandy

Medium-chain acyl-CoA dehydrogenase deficiency is the most common genetic defect of hepatic fatty acid oxidation. Clinical signs are somnolence and lethargy potentially leading to coma. Death occurs during the first attack in about 20% of cases, suggesting sudden infant death syndrome. A point mutation (adenine to guanine at position 985) in exon 11 of the medium-chain acyl-CoA dehydrogenase gene accounts for 90% of medium-chain acyl-CoA dehydrogenase deficiency-causing alleles. Such a high prevalence of a single mutation makes it possible to estimate the incidence of medium-chain acyl-CoA dehydrogenase deficiency in the general population and in sudden infant death syndrome. The study was performed by polymerase chain reaction amplification from blood spots on filter paper in 2000 randomly selected newborns (group I) and in 225 infants dead from sudden infant death syndrome (group II). Among 2000 newborns, 17 were found to be heterozygote for the G985 mutation. In group 11, one child was found with a single copy of the G985 mutation. So. the estimated frequency of the G985 mutation in the general population was 1/118 and the incidence of medium-chain acyl-CoA dehydrogenase deficiency was calculated as around 1/45 000 in Normandy.     

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.     

Recognition of medium-chain acyl-CoA dehydrogenase deficiency in asymptomatic siblings of children dying of sudden infant death or Reye-like syndromes

The medium-chain acyl-CoA dehydrogenase (MCAD) deficiency of mitochondrial beta oxidation has been identified in two asymptomatic siblings in a family in which two previous deaths had been recorded, one attributed to sudden infant death syndrome and the other to Reye syndrome. Recognition of this disorder in one of the deceased and in the surviving siblings was accomplished by detection of a diagnostic metabolite, octanoylcarnitine, using a new mass spectrometric technique. This resulted in early treatment with L-carnitine supplement in the survivors, which should prevent metabolic deterioration. Further studies suggest that breast-feeding may be protective for infants with MCAD deficiency. Families with children who have had Reye syndrome or in which sudden infant death has occurred are at risk for MCAD deficiency. We suggest that survivors and asymptomatic siblings should be tested for this treatable disorder.     

The frequency of a disease-causing point mutation in the gene coding for medium-chain acyl-CoA dehydrogenase in sudden infant death syndrome

A number of rare inherited metabolic disorders are known to lead to death in infancy. Deficiency of medium-chain acyl CoA dehydrogenase has, on clinical grounds, been related particularly to sudden infant death syndrome. The contribution of this disorder to the etiology of sudden infant death syndrome is still a matter of controversy. The present study investigated 120 well-defined cases of sudden infant death syndrome in order to detect the frequency of the most common disease-causing point mutation in the gene coding for medium-chain acyl-CoA dehydrogenase (G985) compared with the frequency in the general population. A highly specific polymerase chain reaction assay was applied on dried blood spots. No over-representation of homo- or heterozygosity-for G985 appears to exist in such a strictly defined population, for which reason it may be m'bre relevant to look at a broader spectrum of clinical presentations of inherited metabolic disorders and examine a wider range of sudden death in infancy.     

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.     

Medium-Chain Acyl-Coa Dehydrogenase Deficiency: Postmortem Diagnosis in a Case of Sudden Infant Death and Neonatal Diagnosis of an Affected Sibling

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is an inherited disorder of fatty acid oxidation associated with sudden death in infants and, in its fulminant form(s), a Reye-like syndrome. In an 18-month-old female who died suddenly and unexpectedly, the postmortem diagnosis of MCAD deficiency was made by analysis of organic acids, acylglycines, and acylcarnitines and by analysis of the most common mutation causing MCAD deficiency (A985G) in a sample of heart blood obtained at autopsy and frozen at—20° C for 8 months. The patient was homozygous for A985G and metabolites characteristic of MCAD deficiency were identified. Parents and an older sibling were heterozygous for A985G. The mother was 6 months pregnant when the results were known. At the birth of her male infant, blood spot cards and urine were obtained. The infant was homozygous for A985G by analysis of DNA extracted from blood spots and he excreted metabolites characteristic of MCAD deficiency. These results demonstrate the use of novel molecular and metabolite analysis in making the postmortem diagnosis of MCAD deficiency. The neonatal diagnosis of an affected sib permits the institution of appropriate dietary measures to prevent potentially fatal episodes of illness.     

Urinary excretion of l-carnitine and acylcarnitines by patients with disorders of organic acid metabolism: evidence for secondary insufficiency of l-carnitine

Concentrations of l-carnitine and acylcarnitines have been determined in urine from patients with disorders of organic acid metabolism associated with an intramitochondrial accumulation of acyl-CoA intermediates. These included propionic acidemia, methylmalonic aciduria, isovaleric acidemia, multicarboxylase deficiency, 3-hydroxy-3-methylglutaric aciduria, methylacetoacetyl-CoA thiolase deficiency, and various dicarboxylic acidurias including glutaric aciduria, medium-chain acyl-CoA dehydrogenase deficiency, and multiple acyl-CoA dehydrogenase deficiency. In all cases, concentrations of acylcarnitines were greatly increased above normal with free carnitine concentrations ranging from undetectable to supranormal values. The ratios of acylcarnitine/carnitine were elevated above the normal value of 2.0 +/- 1.1. l-Carnitine was given to three of these patients; in each case, concentrations of plasma and urine carnitines increased accompanied by a marked increase in concentrations of short-chain acylcarnitines. These acylcarnitines have been examined using fast atom bombardment mass spectrometry in some of these diseases and have been shown to be propionylcarnitine in methylmalonic aciduria and propionic acidemia, isovalerylcarnitine in isovaleric acidemia, and hexanoylcarnitine and octanoylcarnitine in medium-chain acyl-CoA dehydrogenase deficiency. The excretion of these acylcarnitines is compatible with the known accumulation of the corresponding acyl-CoA esters in these diseases. In this group of disorders, the increased acylcarnitine/carnitine ratio in urine and plasma indicates an imbalance of mitochondrial mass action homeostasis and, hence, of acyl-CoA/CoA ratios. Despite naturally occurring attempts to increase endogeneous l-carnitine biosynthesis, there is insufficient carnitine available to restore the mass action ratio as demonstrated by the further increase in acylcarnitine excretion when patients were given oral l-carnitine.(ABSTRACT TRUNCATED AT 250 WORDS)     

Metabolic defects with hypoketotic hypoglycemia

Metabolic defects resulting in hypoketotic hypoglycemia can lead to hepato-encephalopathy and can be lethal. Recognition of the association of hypoglycemia with hypoketonemia is essential for efficient diagnostic and therapeutic procedures. The pattern of urinary excretion of organic acids is useful in differential diagnosis between the possible metabolic defects, viz. carnitine deficiency, carnitine palmitoyl transferase deficiency, medium-chain, long-chain and multiple acyl-CoA dehydrogenase deficiencies, and HMG-CoA lyase deficiency. These (except for carnitine deficiency) can be confirmed by enzyme activity measurements in cultured fibroblasts and tissue biopsies and prenatally. Treatment is available for all of them except some cases of multiple acyl-CoA dehydrogenase deficiency. Genetic counselling of the families must be based on a precise biochemical diagnosis.     

Acyl coenzyme A dehydrogenase deficiency of medium-chain fatty acids in a 9-year-old boy with adymia. A rare mitochondrial cytopathy which may be more common than previously assumed]

The medium-chain acyl-CoA dehydrogenase (MCAD) deficiency of mitochondrial beta oxidation has been identified in a nine-year old boy with a very bland course and easy fatigue as the main symptom. Repeated low frequency stimulation test and EMG for excluding a myasthenia gravis, and screening for urinary organic acid excretion were helpful for the diagnosis. The EMG test at the m. trapezius by stimulation of the n. accessorius showed an extreme decrease of muscle power down to 49%. After i.v. injection of Edrophonium the loss of power of 20% was still significant, so that we could exclude a myasthenia gravis, but we had found signs of a generalised defect in cell chemistry. The diagnosis could be confirmed by a positive 3-phenylpropionic acid-test and moleculargenetic proof of the Adenine to Guanine mutation at position 985 in the MCAD cDNA (G985) with the polymerase chain reaction. The incidence of this organic aciduria is probably 1:60,000 in Germany, but with more attention to this disease and diagnosis of cases with bland courses the incidence will be higher. The MCAD-defect should be considered in the differential diagnosis of patients with Reye syndrome-like encephalopathies, non-ketotic hypoglycaemia or sudden unexpected deaths in infancy.     

Medium-chain acyl-CoA dehydrogenase deficiency: postmortem diagnosis in a case of sudden infant death and neonatal diagnosis of an affected sibling.

Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency is an inherited disorder of fatty acid oxidation associated with sudden death in infants and, in its fulminant form(s), a Reye-like syndrome. In an 18-month-old female who died suddenly and unexpectedly, the postmortem diagnosis of MCAD deficiency was made by analysis of organic acids, acylglycines, and acylcarnitines and by analysis of the most common mutation causing MCAD deficiency (A985G) in a sample of heart blood obtained at autopsy and frozen at -20 degrees C for 8 months. The patient was homozygous for A985G and metabolites characteristic of MCAD deficiency were identified. Parents and an older sibling were heterozygous for A985G. The mother was 6 months pregnant when the results were known. At the birth of her male infant, blood spot cards and urine were obtained. The infant was homozygous for A985G by analysis of DNA extracted from blood spots and he excreted metabolites characteristic of MCAD deficiency. These results demonstrate the use of novel molecular and metabolite analysis in making the postmortem diagnosis of MCAD deficiency. The neonatal diagnosis of an affected sib permits the institution of appropriate dietary measures to prevent potentially fatal episodes of illness.