Objective:To investigate the clinical characteristic and genetic variants of children with carnitine palmitoyltransferase 2(CPT2)deficiency.Methods:The clinical and genetic data of 6 children with CPT2 deficiency were retrospectively analyzed.The blood acylcarnitines and genetic variants were detected with tandem mass spectrometry and whole-exon gene sequencing,respectively.Results:There were 4 males and 2 females with a mean age of 32 months(15 d-9 years)at diagnosis.One case was asymptomatic and with normal laboratory test results,2 had delayed onset,and 3 were of infantile type.Three cases were diagnosed at neonatal screening,and 3 cases presented with clinical manifestations of fever,muscle weakness,and increased muscle enzymes.Five children presented with decreased free carnitine and elevated levels of palmitoyl and octadecenoyl carnitines.CPT2 gene variants were detected at 8 loci in 6 children(4 harboring biallelic mutations and 2 harboring single locus mutations),including 3 known variants(p.R631C,p.T589M,and p.D255G)and 5 newly reported variants(p.F352L,p.R498L,p.F434S,p.A515P,and c.153-2A>G).It was predicted by PolyPhen2 and SIFT software that c.153-2A>G and p.F352L were suspected pathogenic variants,while p.R498L,p.F434S and p.A515P were variants of unknown clinical significance.Conclusions:The clinical phenotypes of CPT2 deficiency are diverse.An early diagnosis can be facilitated by neonatal blood tandem mass spectrometry screening and genetic testing,and most patients have good prognosis after a timely diagnosis and treatment.

Objective:To analyze regional differences in MMACHC gene variations among patients with cblC-type methylmalonic acidemia (MMA) in China and to explore the relationship between these variations and neonatal screening, biochemical markers and prognosis.Methods:Retrospective case summary. Clinical and laboratory data, including general condition, biochemical markers and genetic analysis, were collected from 1 859 cblC MMA patients from 2005 to 2023. Patients were divided into 7 groups according to their regions: north China, northeast China, east China, central China, south China, southwest China and northwest China. They were also classified into neonatal screening and non-neonatal screening groups. Mann-Whitney U and Kruskal-Wallis tests were used to compare biochemical marker levels. In contrast, the Chi-square test was applied to compare MMACHC gene variant frequencies, neonatal screening proportion, onset age and prognosis between groups. Results:Among 1 859 cases of cblC MMA, 1 019 were male and 840 were female, with a consultation age of 1.0 (0.1, 5.0) month. A total of 1 787 cases carried compound heterozygous or homozygous variants and only 1 variant site was identified in 72 cases. The 10 most frequent variants were c.609G>A (1 238 cases), c.658_660delAAG (343 cases), c.80A>G (284 cases), c.482G>A (239 cases), c.567dupT (191 cases), c.656_658delAGA (131 cases), c.217C>T (109 cases), c.394C>T (105 cases), c.445_446delTG (51 cases) and c.1A>G (50 cases). The frequency of the c.609G>A was the lowest in northwest China (28.8% (44/154), χ2=-18.42, P<0.05). The frequency of the c.567dupT was the most common in southwest China (25.0% (20/80), χ2=71.70, P<0.001) and c.656_658delAGA had the highest frequency in northeast China (9.3% (19/205), χ2=32.08, P<0.001). Non-missense variants (91.2% (62/68), 88.5% (46/52)) and early-onset patients (90.0% (36/40), 94.4% (34/36)) were both more prevalent in southwest and south China ( χ2=14.95, 31.69, both P<0.05). The proportion of neonatal screening was the lowest in south China (22.2% (8/36), χ2=98.48, P<0.05), where the mortality rate was the highest (19.1% (4/21), χ2=38.98, P<0.001). East China exhibited the highest frequency of missense variants (21.5% (339/1 579)), the highest proportion of patients identified through neonatal screening (54.5% (465/853)), and a more significant proportion of patients with good prognosis (36.6% (227/621), χ2=14.57, 93.49, 38.98, all P<0.05). In addition, the c.482G>A variant was more frequent in patients diagnosed by neonatal screening compared to those diagnosed by other methods (8.3% (132/1 586) vs. 5.9% (122/2 060), χ2=7.97, P<0.05). Conclusions:The frequency of MMACHC gene variation varies across different regions. The c.609G>A was least frequent in northwest China, c.567dupT was most common in southwest China, and c.656_658delAGA was most prevalent in northeast China. South China had the lowest neonatal screening rate and the highest mortality. At the same time, east China exhibited the highest frequency of missense variants, the highest proportion of patients identified through neonatal screening and the best prognosis. The c.482G>A variant was more frequent in patients diagnosed by neonatal screening compared to those diagnosed by other methods.

OBJECTIVE: To explore the disease spectrum for abnormal 3-hydroxyisovalerylcarnitine (C5OH) metabolism identified through newborn screening and clinical diagnosis patients and the key points for differential diagnosis so as to raise the awareness of pediatricians for such diseases. METHODS: Clinical data of 85 neonates with abnormal C5OH metabolism identified from February 2004 to January 2022 at Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine were collected. Their clinical manifestations and results of tandem mass spectrometry (MS/MS), gas chromatography mass spectrometry (GC-MS) and genetic testing were retrospectively analyzed. RESULTS: Among the 85 cases, 46 (54.1%) were identified by neonate screening, whilst 39 (45.9%) were clinically diagnosed patients. Five diseases were diagnosed, including 28 cases with multiple carboxylase deficiency (MCD, 32.9%), 29 cases with 3-methylcrotonyl-coenzymeAcarboxylasedeficiency (MCCD, 34.1%), 4 cases with 3-methylglutaconic acid (3-MGA, 4.7%), 7 cases with 3-hydroxy-3-methylglutaric acid (3-HMG, 8.2%), and 17 cases with beta-ketothiolase deficiency (BKD, 20.0%). The disorders were characterized by sudden onset, anorexia, vomiting, diarrhea, abnormal breathing, consciousness disorder, spasm and developmental delay. CONCLUSION Among newborns with abnormal C5OH metabolism, MCCD is the most common disorder, which was followed by BKD and MCD. For patients with abnormal C5OH metabolism, MCD is the most common, followed by BKD and 3-HMG. C5OH related diseases have great heterogeneity. Combination of blood acylcarnitine levels, urinary organic acid levels and genetic testing based on clinical characteristics can help to attain the diagnosis.
Humans ; Infant, Newborn ; China ; Neonatal Screening ; Retrospective Studies ; Tandem Mass Spectrometry/methods*

Objective:To analyze the disease spectrum of lysosomal storage disorders(LSDs) and explore the prevalent distributions of different LSD types in one center in Shanghai.Methods:A retrospective analysis was made.A total of 5 476 suspected LSD patients, including 3 415 males and 2 061 females, with a median age of 4 years(1 day to 72 years), were collected from Xinhua Hospital, Shanghai Jiaotong University School of Medicine from August 2008 to May 2022.The activity of different lysosomal enzymes was detected by fluorescent and biochemical methods.Results:A total of 1 520 patients were diagnosed with LSDs, including 972 males and 548 females, with a median age of 4 years(1 day to 59 years), involving 19 different subtypes.Mucopolysaccharidosis(MPS) was the most common type among LSDs, with a frequency of 45.46%(691/1 520), followed by sphingolipidoses [33.88%(515/1 520)] and glycogen storage disease type Ⅱ [16.05%(244/1 520)] successively.MPS Ⅱ was the most common type in MPS, with a frequency of 45.73%(316/691), followed by MPS ⅣA [22.87%(158/691)]. Niemann-Pick A/B, Gaucher, and Krabbe diseases were common in Sphingolipidoses patients, with frequencies of 37.09%(191/515), 34.37%(177/515), and 10.29%(53/515), respectively.Conclusions:LSDs are common genetic metabolic diseases, especially MPS and sphingolipidoses.Newborn screening for LSDs should be carried out timely so that the patients can be treated early and their prognosis can be improved.

Methylmalonic acidemia (MMA) is a series of rare inherited organic acid metabolic disorders with variable and nonspecific clinical manifestations, in particular neurological symptoms such as vomiting, lethargy, etc. Even with timely treatment, patients may still have various degrees of neurological complications and can even die. The prognosis is mainly related to the type of genetic variants, level of metabolites, newborn screening, onset of disease and early initiation of treatment. This article has reviewed the prognosis of patients with various types of MMA and factors that may affect it.
Infant, Newborn ; Humans ; Amino Acid Metabolism, Inborn Errors/complications* ; Prognosis ; Mutation ; Neonatal Screening ; Propionic Acidemia

Newborn screening is an effective measure for early detection and early treatment of rare genetic diseases. Among the three-level preventive measures to reduce birth defects, newborn screening has a significant preventive effect, and continues to develop with the advancement of new therapies and new technologies. Newborn screening is also relatively more reliable to obtain data on the prevalence of rare diseases. This article introduces the history and current status of neonatal screening for newborn hereditary metabolic disease in China, presents the disease spectrum and prevalence of 7 819 662 cases of neonatal screening by tandem mass spectrometry, and proposes 12 rare diseases as the primary targeting diseases for newborn screening by tandem mass spectrometry in China. At last, the article raises and discusses the issues of requirement for technology development and ethics of newborn screening.

The developments of mass spectrometry and gene detection technology and the introduction of newborn screening have led to an expanding population of patients with inherited metabolic diseases.Therapies of inherited metabolic diseases have attracted much attention.The basic principles of management in these diseases are to limite the consumption of nutrients that produce toxic products, supplement deficient substances, and increase excretion of toxic metabolites.Dietary therapy is one of the major treatments for many inherited metabolic disorders, with the starting point of limiting the intake of substrates for metabolic disorders and supplementing products of insufficient synthesis or alternative energy sources to bypass the defective pathway in order to maintain normal growth and development.With more and more special medical formula nutritional foods being put into production and use, dietary therapy become accessible and compliant.With the effective dietary therapy, many patients get clinical symptom controlled, and their quality of life has been improved.This article mainly elaborates the common inherited metabolic diseases dietary therapy.

Objective:To investigate the spectrum of amino acid, organic acid, and fatty acid oxidative metabolic diseases in children diagnosed by detecting urinary organic acid levels using gas chromatography-mass spectrometry.Methods:From January 2005 to December 2021, clinical data of 2 461 children diagnosed with inherited metabolic diseases (IMD) by gas chromatography-mass spectrometry, in combination with tandem mass spectrometry and genetic testing in Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine were retrospectively analyzed.Results:Among 2 461 children, 1 446 were male and 1 051 were female. A total of 32 types of IMD were detected among 2 461 patients, which included 10 amino acid disorders in 662 cases (26.9%), 6 common diseases were hyperphenylalaninemia, citrin deficiency, ornithine carbamoyltransferase deficiency, maple syrup urine disease, alkaptonuria, and tyrosinemia-I, 17 types of organic acidemias in 1 683 cases (68.4%), 6 common diseases were methylmalonic acidemia, propionic acidemia, valeric acidemia-type Ⅰ, isovaleric acidemia, 3-methylcrotonyl-CoA carboxylase deficiency and multiple carboxylase deficiency and 5 fatty acid β oxidative defects in 116 cases (4.7%), 2 common diseases were multiple acyl-CoA dehydrogenase deficiency and short-chain acyl-CoA dehydrogenase deficiency).Conclusion:Among the diseases diagnosed by analyzing urinary organic acid profiling with gas chromatography-mass spectrometry, the most common are organic acidemias, followed by amino acid disorders and fatty acid oxidation defects.

Objective:To investigate the treatment and prognosis of children with propionic acidemia (PA).Methods:This study involved 82 children with PA treated in the Department of Pediatric Endocrinol-ogy and Genetic Metabolism, Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine from December 2002 to June 2020. Clinical data, including manifestations, laboratory test results, treatment strategy, and follow-up data, were summarized and analyzed using t-test or Mann-Whitney U test. Results:(1) Among the 82 cases consisting of 50 (61.0%) boys and 32 (39.0%) girls, 59 (72.0%) were diagnosed after clinical onset; 22 (26.8%) were diagnosed by newborn screening, including eight asymptomatic ones; the other one (1.2%) was asymptomatic but confirmed after the diagnosis of PA in the patient's sibling. The average age at first onset was 4.5 months (2 d-5 years) in 73 subjects, of which 28 (38.4%) were early-onset PA (within three months after birth). (2) Cranial MRI was performed on 26 cases, and abnormality was identified in 19 (73.1%) cases. (3) Hyperlactatemia was found in 16 cases among 30(53.3%) who underwent relevant examination with the average lactic acid level of 3.5 (2.1-4.3) μmol/L, while 35 out of 40 patients (87.5%) had hyperammonemia with an average blood ammonia level of 105.4 (34-907) μmol/L. (4) Among the 28 early-onset PA cases, 16 (57.1%) died, and 12 (42.9%) survived. There was no significant difference in the serum propionylcarnitine level, propionylcarnitine to acetylcarnitine ratio, urine 3-hydroxypropionic acid, or methylcitrate level between the survival and death cases. (5) Genetic mutations were detected in 75 patients (91.5%), among which 26 (34.7%) carried PCCA gene mutations and 48 (64%) with PCCB gene mutations. One patient (1.3%) harbored one known pathogenic mutation in each of the PCCA and PCCB genes. All mutations were inherited from the parents. (6) Followed up to June 2020, 57 (69.5%) patients survived, and 25 (30.5%) died from multiple organ failure secondary to severe acidosis, including 16 early-onset and nine late-onset cases. Conclusions:The primary treatment of PA is dietary control. Most PA patients are diagnosed after clinical onset, but symptoms may recur and even have developmental retardation despite treatment. Some of those diagnosed through newborn screening are asymptomatic after treatment. Newborn screening using tandem mass spectrometry is recommended for early diagnosis and treatment of PA.

Objective:Nuclear magnetic resonance spectroscopy (NMR) was used to detect the species and content of metabolites in urine of patients with inherited metabolic diseases, and to explore the application value of NMR technology in the diagnosis of inherited metabolic diseases.Methods:Urine samples were collected from 20 patients with inherited metabolic diseases diagnosed in Xinhua Hospital, Shanghai Jiaotong University School of Medicine from March to June 2019, including 9 cases of methylmalonic acidemia (MMA). NMR pulse length-based concentration determination and Gas chromatography mass spectrometry (GC/MS) semi-quantitative method were used to detect the composition of metabolites in urine samples of patients with inherited metabolic diseases, and the levels of abnormal metabolites in the two methods were analyzed.Results:NMR technology can detect the levels of characteristic metabolites significantly increased in the urine of patients with MMA, isovalerinemia, glutaric acidemia, propionic acidemia, 3-methylcrotonyl-CoA carboxylase deficiency, ornithine carbamyltransferase deficiency, Citrin deficiency, Canavan disease, tyrosinemia and lysinuria protein intolerance. The average is 8 times of the upper limit of the reference value, and the highest is 545 times. Compared to GC/MS, NMR technology can detect the levels of various metabolites such as organic acids, amino acids and sugars. In 9 cases of untreated MMA,the median levels of methylmalonic acid and 3-hydroxypropionic acid in NMR [1 800 (180-12 000) and 50 (0-270) mmol/mol Cr] were higher than the reference values (0-31, 0-35). The median levels of methylmalonic acid and methylmalonic acid in GC/MS [136.56 (43.79-518.67) and 4.87 (1.52-7.52)] were higher than the reference values (0-4 and 0-0.7).Conclusions:NMR and GC/MS technologies are specific for the diagnosis of organic acidemia. The primary component detected by GC/MS is organic acid. NMR technology can break through this limitation and measure the level of various metabolites in urine, which provides a more theoretical basis for the diagnosis and research of inherited metabolic disease.