ABSTRACT
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.
ABSTRACT
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.
Subject(s)
Infant, Newborn , Humans , Amino Acid Metabolism, Inborn Errors/complications , Prognosis , Mutation , Neonatal Screening , Propionic AcidemiaABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
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.
ABSTRACT
Objective To study the dynamic changes of blood carnitine and acylcarnitine levels in preterm infants during parenteral and enteral nutritional support,and the relationship between carnitine status and nutritional patterns,gestational age (GA) and weight gain.Method From January 2017 to December 2017,preterm infants admitted to the neonatal intensive care unit (NICU) within 24 hours after birth and received parenteral nutrition support were enrolled.They were assigned into 4 groups according to their GA:ultra-premature infants (＜ 28 weeks),very premature infants (28 ～ 31 weeks),mid premature infants (32 ～ 33 weeks) and late premature infants (34 ～ 36 weeks).They were assigned into 2 groups according to their average daily weight gain:＜ 15 g/(kg · d) group and ≥15 g/(kg · d) group.Blood samples were collected and examined as dried-blood spot specimens on filter paper for four times:after born,given total parenteral nutrition,given enteral combined parenteral nutrition,and given total parenteral nutrition.The concentrations of free carnitine and acylcarnitine were detected using liquid chromatographytandem mass spectrometry (LC-MS/MS).SPSS 21.0 statistical software was used for statistical analysis.Result A total of 124 preterm infants and 410 samples were collected.As the infants experienced gradual transition from parenteral nutrition to enteral nutrition,the free carnitine and most acylcarnitines levels were decreasing (C3,C4,C10DC,C12,C12∶1,C12DC,C14,C16,C16∶ 1,C16-OH and C18,P＜0.05).Preterm infants with small GA showed higher levels of C4-OH (P =0.001) and C5 (P =0.001).Preterm infants with lower velocity of weight gain showed lower concentration of C5-OH (P =0.006) in the early postnatal period.Conclusion Free carnitine and acylcarnitine in preterm infants during the early postnatal period are decreasing with the transition from parenteral nutrition to enteral nutrition,indicating that the exogenous nutrition is relatively insufficient.C4-OH and C5 levels are negatively correlated with GA.In addition,lower level of C5-OH may indicate slow weight gain during the early postnatal period.
ABSTRACT
Objective:To analyze levels of carnitine and acylcarnitine in peripheral blood from septic infants and to investigate their changes and clinical values in sepsis in infants.Methods:This retrospective research involved 46 septic infants and 55 infants with noninfectious diseases who were hospitalized in Xinhua Hospital, Shanghai Jiao Tong University School of Medicine.The clinical data were collected, the levels of carnitine and acylcarnitine in peripheral blood measured by tandem mass spectrometry were compared between the two groups, and the correlations of acylcarnitine levels with CRP and PCT were analyzed respectively.The septic infants were divided into two groups according to whether there were complications or not.The levels of free carnitine and acylcarnitine were compared between the two groups.Results:The levels of C6DC, C14: 1, C14OH and C16OH in peripheral blood were significantly higher in septic infants than those with noninfectious diseases( Z=-2.52、-2.05、-2.68、-2.82, all P<0.05). There is no significant difference in free carnitine level between two groups.These four acylcarnitine levels were positively correlated with PCT( r=0.44、0.44、0.40、0.49, all P<0.01). In septic group, the percent of infants with abnormal levels of C16OH was significantly higher in infants with complications than those without complications( χ2=4.51, P<0.05). Conclusion:The peripheral blood levels of several acylcarnitine elevate in septic infants, and have positive correlations with the strength of infection.Meanwhile, there is a higher proportion of having abnormal level of long chain acylcarnitine among infants with complications than those without complications.These results suggest that lipid metabolism has changed in septic infants and detecting acylcarnitine levels can be helpful in assessing the severity of sepsis.
ABSTRACT
OBJECTIVE@#To summarize the clinical, biochemical and molecular characteristics of 8 patients with beta-ketothiolase deficiency (BKD).@*METHODS@#Clinical characteristics, biochemical markers detected by tandem mass spectrometry (MS-MS) and gas chromatography-mass spectrometry (GC-MS), and variations of ACAT1 gene of the 8 patients were reviewed.@*RESULTS@#Three patients were diagnosed by newborn screening and were asymptomatic. Five patients showed dyspnea and metabolic acidosis through high risk screening. Blood methylcrotonyl carnitine (C5:1) were 0.43 (0.20-0.89) μmol/L and 3-hydroxyisovaleryl carnitine(C5-OH) were 1.37 (0.98-3.40) μmol/L. Both were significantly higher than those of healthy controls (PG (p.N375S) variant, which accounted for 28.6% of all 14 mutant alleles. Four novel variants, namely c.229delG (p.E77KfsTer10), c.373G>T (p.V125F), c.419T>G (p.L140R) and c.72+1G>A, were discovered. Pathogenicity assessment of two highly conservative missense variants (p.V125F) and (p.L140R) were 0.994 and 1.0 (Scores obtained from PolyPhen2), and PROVEAN scores were -4.652 and -5.399, respectively. c.72+1g>a was suspected (by Human Splicing Finder) to alter the wild type donor motif and most probably affect the splicing.@*CONCLUSION@#Clinicians should consider MS/MS and GC/MS testing for those with unexplained neurological symptoms and metabolic acidosis in order to attain early diagnosis of BKD. Genetic testing should be used to confirm the diagnosis.
Subject(s)
Humans , Infant, Newborn , Acetyl-CoA C-Acyltransferase , Amino Acid Metabolism, Inborn Errors , Carnitine , Retrospective Studies , Tandem Mass SpectrometryABSTRACT
Objective To explore the clinical manifestations, treatment and outcomes of patients with c. 482G>A ( p. R161Q ) variant of MMACHC gene in cblC type methylmalonic acidemia ( MMA ) . Methods The clinical manifestations, mass spectrometry results, genotypes, treatment and outcomes of 75 patients with cblC type MMAcarryingc.482G>A(p.R161Q)variantwereretrospectivelyanalyzed.Results Ofthe75patients,57(76％) were from newborn screening and one of them had an onset. Among the rest 18 unscreened patients, 2 were diagnosed after their full sisters' or brothers' diagnosis, the others were clinical patients. There were 17 clinical patients, with the medium age of onset 12 years old (10 days～26 years old). 12 late onset patients (70.6％) presented with poor academic performance, memory loss, poor expression, and decreased exercise capacity, while 5 early onset patients (29.4％) presented with convulsion and delay of development. All patients were vitamin B12-responsive. The levels of blood propionylcarnitine, the ratio of propionylcarnitine to acetylcarnitine, urinary methylmalonic acid and methyldecanoic acid, and plasma homocysteine were significantly decreased after treatment (P< 0.01). All patients diagnosed from newborn screening had normal development. However, only 3 clinical patients had a rather normal outcomes and the others remained different levels of intelligence and ( or ) motor dysfunction after treatment. Conclusion The c.482G>A ( p. R161Q) variant of MMACHC gene is associated with late onset cblC type MMA. Patients with this variant have a better response to hydroxycobalamin than other variants. The outcome of patients diagnosed from the newborn screening is good. When symptoms occur, the disability rate is often high. Therefore, newborn screening is a recommended method to prevent this disease.
ABSTRACT
Objective To investigate the characteristics of glycogen storage disease type IV (GSD IV) clinically, in laboratory tests and in gene mutation. Methods The clinical manifestations, biochemical indexes, activity of chitotriosidase, and the follow-up of the treatment in 5 cases of GSD IV were analyzed. Results Five patients (3 boys and 2 girls) aged 4 months - 5 years presented hepatosplenomegaly and elevated liver enzyme levels for 2 months at hospital visit. Two patients had motor developmental delay and weakness but their creatine kinase (CK) level were normal. Glycogen storage and liver fibrosis were observed in the liver biopsy in 4 patients. Target sequencing found that all 5 children carried the complex heterozygous mutation of the GBE1 gene with 2 reported mutations(p.R515C,p.R524Q)and 7 novel mutations.The novel mutation contains 5 missense mutations (p.I460T, p.F76S, p.F538V, p.L650R, p.W455R), one insertion mutations (c.141_142insGCGC), and one large fragment deletion (exon 3-7). Therefore, diagnosis of liver type of GSD IV was confirmed in those children. Two patients died of liver cirrhosis. The liver transplantation was performed due to liver cirrhosis in one patient whose chitotriosidase activity increased obviously before transplantation and decreased significantly after the transplantation and liver enzyme levels were returned to normal 4 months after transplantation. In the other two patients their growth and liver enzyme levels were normal;one had not received special treatments while the other was treated with raw corn starch and level of chitotriosidase was normal. Conclusions The clinical manifestations of GSD IV are heterogeneous. Target sequencing can be used for fast and noninvasive diagnosis of GSD IV. Chitotriosidase activity is useful in the prognosis assessment for GSD IV.
ABSTRACT
<p><b>OBJECTIVE</b>To determine the genetic etiology and clinical characteristics of 2 boys featuring development delay (DD).</p><p><b>METHODS</b>Routine chromosomal banding was performed to analyze the karyotypes of the patients and their parents. Single nucleotide polymorphism array (SNP array) analysis was employed to identify pathogenic deletion/duplication of chromosomes, and quantitative real-time PCR (qPCR) was performed to confirm the results.</p><p><b>RESULTS</b>Patient 1 showed a global developmental delay, especially impaired language development, seizures, behavioral problems belonging to the autism spectrum and mild facial dysmorphism. Patient 2 mainly presented with severely delayed speech and moderate intellectual disability, but did not have obvious facial dysmorphism and autistic-like behavior. The diagnosis of 22q13 syndrome was established based on identification of a heterozygous microdeletion at chromosome 22q13.33 in both patients (69 kb and 587 kb, respectively) by the SNP array analysis. Both patients had deletions of SHANK3 and ACR, which are located at the end of 22q. Quantitative real-time PCR verified that the deletion of SHANK3 gene in both patients were de novo in origin.</p><p><b>CONCLUSION</b>Two cases of 22q13 deletion syndrome have been diagnosed by SNP array analysis. Deletion of SHANK3 gene may be the major contributor to the clinical manifestations of the patients. SNP array analysis can facilitate discovery of microdeletions, which has played an important role in the diagnosis and genetic counseling for the family.</p>
ABSTRACT
The application of mass spectrometry(MS)in the detection of inherited metabolic diseases including the following two aspects.The tandem mass spectrometry(MS/MS)technology is applied to detect small molecules(such as amino acid, acyl carnitine, fragments of steroid hormones and lysosomalmetabolites)of dried blood specimens,thus to screen and diagnose relevant diseases.Meanwhile, the gas chromatographic mass spectrometry(GC/MS)is used to test urine organic acid, thus to diagnose organic acidemia, and assist in the diagnosis of amino acid metabolic diseases and fatty acid oxidative diseases.MS has currently been widely used as the main method for screening newborn with these amino acids,organic acids and fatty acids oxidative metabolic diseases.For the newborn screening of adrenal and lysosomal disorders,MS has been used only in several countries.Furthermore, MS could also be used to perform prenatal diagnosis of organic acidemia through detecting acyl carnitine and organic acid in amniotic fluid.
ABSTRACT
Objective To explore the value of the combination of homocysteine analysis, liquid chromatography tandem mass spectrometry(LC-MS/MS)and gas chromatography mass spectrometry(GC/MS)in the prenatal diagnosis of combined methylmalonic acidemia and homocystinuria(cblC defect)in amniotic fluid.Methods This is a retrospective study of 187 cases of pregnancies that came to our hospital for prenatal diagnosis between 2014/01-2017/03,among which 78 cases′probands were cblC defect patients and 109 cases′probands were not organic academia patients(control group).Amniotic fluid samples from pregnant women were obtained at 16 -24 weeks of gestation.Propionylcarnitine(C3)and acetylcarnitine (C2)were measured by LC-MS/MS, methylmalonic acid and methylcitric acid were analyzed by GC /MS, and homocysteine was determined by fluorescence polarization immunoassay.Some pregnancies received MMACHC gene sequencing with cultured cells from amniotic fluid.Data were analyzed using Mann-Whitney U and Kruskal-Wallis H tests.Results Among those 78 pregnant women whose probands were diagnosed to be cblC defect,24 cases were diagnosed to be cblC defect(positive group)and 54 pregnant women were diagnosed to be negative(negative group).In positive group, levels of homocysteine, C3, C3/C2, methylmalonic acid and methylcitric acid were all significantly higher than their normal reference ranges, negative group and control group(P values are 0.00).Cases that were diagnosed to be cblC defect by MMACHC gene sequencing were all turned out to be positive in the tests of the above metabolites in amniotic fluid.Cases with negative results of the metabolites were all excluded to be cblC defect by gene sequencing. Besides,2 cases of pregnancies were diagnosed to be positive by homocysteine and mass spectrometric analysis while only one mutation were detected by gene sequencing.Conclusions The combination of homocysteine, LC-MS/MS and GC/MS analysis in amniotic fluid turns out to be reliable for prenatal diagnosis of cblC defect,which may further cover the defect of prenatal diagnosis of those pregnancies whose probands′gene mutation is unknown.
ABSTRACT
Objective To investigate the preparation method of dry blood spots (DBS) control materials for steroids used for internal quality control by liquid chromatography tandem mass spectrometry (LC-MS/MS). Methods Whole blood was collected and the blood cells and plasma were separated. The blood cells were washed by saline. The activated charcoal was added to the plasma. Standard substance was added to make different concentrations (low, medium, and high) of DBS control materials for steroids. The precision, accuracy, stability, and differences among different blood spots were detected and analyzed by LC-MS/MS. Results The inter-day precision and accuracy of DBS control materials for steroids were 2.4%-7.0% and 102.0%-111.0%, respectively, and the intra-day precision and accuracy were 5.1%-9.8% and 99.0%-114.8% respectively. The DBS control materials for steroids were stored for 5 months, and there was no difference among the different months (P>0.05). The coefficients of variation among different blood spots were small, 3.3%-8.2%. Conclusions The DBS control materials for steroids has good precision, accuracy and stability. The difference among different blood spots is small and meet the requirements of indoor quality control products. They can be used for the internal quality control in steroids detection by LC-MS/MS.
ABSTRACT
Objective To investigate the clinical, laboratory and genetic features of glycogen storage disease(GSD)IXc. Methods Five patients suspected as liver GSD were included in our study. DNA was extracted from peripheral blood of all the patients and diagnoses were made after target sequencing to nearly 2700 disease causing genes. All detected mutations were confirmed in the probands and their parents. Further analysis was based on clinical features, routine laboratory examinations and treatment. Results All the 5 patients manifested with severe hepatomegaly, hypoglycemia, moderately to severely elevated liver enzyme levels, hypertriglyceridemia and growth retardation. Four cases showed poor exercise tolerance but with normal creatine kinase (CK) levels. None of the patients showed liver cirrhosis. Growth velocity and hepatomegaly was improved after the uncooked corn starch treatment was initiated. In the 5 patients, 6 different pathogenic or likely pathogenic mutations in the PHKG2 gene were identified, including one reported mutation (p.E157K) and five novel mutations (p.E56X, p.R185X, c.79_88delinsTCTGGTCG, c.761delC,p.R279C). The p.E157K was the most frequently mutation identified (6/12, 50%). Conclusions The p.E157K mutation is the hot mutation in our small cohort. Main clinical features of our patients include fasting hypoglycemia, impaired liver function,short statures and poor exercise tolerance, without developing liver cirrhosis.
ABSTRACT
Objective To analyze the influence of validating the parental origin to the interpretation of clinical pathogenicity of total 54 copy number variations(CNV)with different clinical significance in 46 patients undergo chromosomal microarray analysis(CMA).Methods A retrospective study.This study enrolled 46 patients conducted in Department of Pediatric Endocrinology and Genetics of Shanghai Xinhua Hospital during the period of August 2014 to December 2015,involving 54 different CNVs detected by CMA.The parental origin of CNVs was examined by CMA or quantitative real-time polymerase chain reaction.Results Totally 54 different CNVs were found in 46 patients by CMA.Seventeen out of the 54 CNVs were pathogenic variations.After validating the parental origin,14 CNVs were proved de novo mutation,while 3 CNVs have maternal origin including 1q21.1 deletion syndrome,Xq27.3q28 and Xq22.1q22.3 duplications which inherited from maternal X chromosome.CNVs of 1q21.1 deletion syndrome often inherited from parents,and no phenotype appears on mother which may be due to the deactivation mechanism of duplications on mother′s X chromosome.Therefore,these 17 pathogenic variations were still considered to be clinical pathogenic significance after validating the parental origin.Ten out of 54 CNVs were variants of uncertain significance-likely pathogenic.After parental original validation,3 CNVs were proved de novo mutation considering likely pathogenic significance,while 7 CNVs have parental origin still judged to be unknown clinical pathogenicity.Twenty-seven out of 54 CNVs were variants of uncertain significance.After validating the parental origin,only 1 CNV was proved de novo mutation considering likely pathogenic significance,while all the others had parental origin considered to be variations likely benign.Conclusion CNVs reported as likely pathogenic should be validated the parental origin in order to further study their clinical pathogenicity,while variants of uncertain significance can preliminary clear its nature by validating parental origin.
ABSTRACT
Objective@#To investigate the value of amniotic fluid metabolite detection by mass spectrometry combined with gene mutation analysis in the prenatal diagnosis of glutaric acidemia type Ⅰ (GA-Ⅰ).@*Method@#From January 2009 to December 2016, Department of Pediatric Endocrinology and Genetic, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine carried out prenatal diagnosis for 24 cases of pregnant women with GA-Ⅰproband. 24 pregnant women without organic acidemia proband for conventional prenatal diagnosis at the same period were used as the control group. The pregnant women of the two groups had the amniocentesis at 16 to 20 weeks of gestation.The levels of glutaryl carnitine (C5DC) and octanoylcarnitine (C8) in amniotic fluid were detected by tandem mass spectrometry, and the levels of glutaric acid was determined by gas chromatography-mass spectrometry. All the amniotic fluid cells underwent GCDH gene testing.@*Result@#A total of 4 cases of fetuses were diagnosed by gene mutation analysis combined with mass spectrometry detection, the levels of C5DC (1.58(0.89-2.85) μmol/L), C5DC/C8 (19.74(12.40-25.93))and glutaric acid (129.96 (90.09-66.02) mmol/mol Cr) were significantly higher than the upper limit of the reference, of which in one case with the proband only on mutation was detected, and in the amniotic fluid cells also only one mutation was detected, the diagnosis was made according to the significantly increased levels of amniotic fluid C5DC, C5DC/C8 and glutaric acid. Twenty cases of fetuses were identified as non-GA-Ⅰchildren, of whom in 2 cases of proband only one mutation was detected, and also in amniotic fluid cells one mutation was detected, in 2 cases the diagnosis was excluded because the normal levels of C5DC, C5DC/C8 and glutaric acid. There were 2 cases whose levels of C5DC or glutaric acid were slightly higher than the upper limit of the reference, but the diagnosis was excluded according to genetic testing.@*Conclusion@#Prenatal diagnosis cannot be made by gene analysis when the proband mutation is not clear, and it cannot determine whether the fetus is patient when the mass spectrometry detection of amniotic fluid metabolite is mildly abnormal, while mass spectrometry detection of amniotic fluid C5DC, C5DC/C8 and glutaric acid levels combined with GCDH gene analysis can make up the deficiencies, and make the prenatal diagnosis of GA-Ⅰ more reliably.
ABSTRACT
Objective@#To investigate the clinical and laboratory features of three children with late-onset type Ⅱ glycogen storage disease(GSD) who presented with hypertrophic cardiomyopathy and to analyze the effect of five mutations identified on the acid-α-glucosidase (GAA) activity and stability.@*Method@#Three cases of children with muscle weakness were included in this study.GAA activity was analyzed in Dried Blood Spot of the patients.DNA was extracted from peripheral blood in all the patients and their parents and subjected to polymerase chain reaction and directly sequencing of GAA gene.Five mutant pcDNA3.1-myc-his-GAA expression plasmids(p.G478R, p.P361L, p.P266S, p.Q323X, p.R672Q) were constructed and transient instantaneously transfected into 293T cells to analyze the enzyme activity and stability of GAA.@*Result@#All the three children had the onset of disease at 3 years or 1.5 years of age.They presented with developmental delay, muscle weakness and hypertrophic cardiomyopathy.GAA activity of 3 patients was 2.65, 3.55 and 1.51 pmol(punch·h)(8.00-98.02)respectively. Genetic analysis found 5 mutations (p.G478R, p. P361L, p. P266S, p. Q323X, p. R672Q), and all of these 3 cases had clinical manifestations and were diagnosed as late-onset type Ⅱ glycogen storage disease.Five mutant pcDNA3.1-myc-his-GAA expression plasmids were transfected into 293T cells.Five mutant enzyme activities were found to be only 9.9%-22.5% of the wild-type enzyme activity and the protein expression of the five mutants was 32.0%-63.9% compared with the wild type.@*Conclusion@#This study reports 3 children with late-onset GSD Ⅱ accompanied by hypertrophic cardiomyopathy and compensatory stage of cardiac function in addition to limb muscle weakness.Five pathogenic mutations were identified, and these 5 mutations result in decreased GAA activity and GAA expression by in vitro functional analysis.
ABSTRACT
Objective Establish a method for measuring the activities of Galactocerebrosidase (GALC), α-Glucosidase(GAA), α-Galactosidase (GLA) and α-L-Iduronidase (IDUA) in dried blood spots specimen by tandem mass spectrometry ( MS/MS ).Methods A total of 2175 dried blood spot samples forinborn errors of metabolism in neonatalscreening center of Shanghai Xinhua hospital were collected in July and November, 2013.And twenty dried blood spot samples from patients withlysosomalstorage disorders( LSDs) of Shanghai Xin Hua Hospital were collected from September 2012 to January 2014.The extraction of DBS was incubated with enzyme substrates and internal standards.After liquid-liquid and solid-phase extraction, the extraction solution was dried under nitrogen and reconstituted.Then enzyme reaction products and internal standards were analyzed by MS/MS.Linearity, precision, accuracy and the limit of detection were evaluated.2175 dried blood spot samples were detected to establish the normal reference range for the activities of four enzymes according to 0.5th to 99.5th percentiles.20 specimens from patients withLSDs were detected to verify the reference range inclinical judgment.Results The intraassay and interassay precisions ranged from 1.7%to 11.8%, and the intraassay and interassay accuracies ranged from 85%to 115%.The linear coefficients for measured concentration of enzyme products/internal standards and theoretical concentration were 0.997-0.999.The limits of detection forGALC, GAA, GLA and GLA were 0.03 μmol/(L· h), 0.09 μmol/(L· h), 0.12 μmol/(L· h) and 0.16 μmol/(L· h) .The normal reference values for GALC, GAA, GLA and GLAwere 0.51-8.51μmol( L· h) ,1.99-22.22μmol/( L· h),1.68-41.59 μmol/(L· h) and 2.36-19.21 μmol/(L· h).The enzymes of 20 patients with LSDs were remarkably decreased compared to the normal range.The Krabbe, Pompe, Fabry, MPSⅠpatients can be effectively detected by this MS/MS method.Conclusions A MS/MS method for measuring GALC, GAA, GLA and IDUA enzyme activities in DBShas been established.