Association Analysis of Gene Sequencing by NeoSeq Combined with Tandem Mass Spectrum and Four Neonatal Diseases.

BACKGROUND: NeoSeq is a new method of gene sequencing for newborn screening. The goal is to explore the relationship between gene sequencing by NeoSeq combined with tandem mass spectrum (TMS) and four neonatal diseases. METHODS: A total of 1,989 newborns from August 2010 to December 2021 were enrolled. The case number of congenital hypothyroidism, phenylketonuria, adrenocortical hyperplasia, and glucose-6-phosphate dehydrogenase deficiency was counted, and the results of gene sequencing by NeoSeq and TMS were analyzed. RESULTS: The proportion of male newborns was higher than that of female newborns (51.68% vs. 48.32%). The detection rate of glucose-6-phosphate dehydrogenase deficiency was higher than that of the other three diseases (0.60% vs. 0.05%, 0.05%, 0.15%). A total of 121 newborns were recalled from 1989 newborns by traditional screening technique, and TMS detected phenylketonuria, citrullinemia, glutaric acidemia type I, and 3-methylcro-tonyl-CoA carboxylase deficiency in 1 newborn each. Gene sequencing by NeoSeq of newborns with positive TMS results confirmed the presence of susceptibility genes, and 17 of 1,868 newborns with normal biochemical tests had pathogenic genes. CONCLUSIONS: The incidence of glucose-6-phosphate dehydrogenase deficiency is relatively higher in four neonatal diseases, and the detection rate of gene sequencing by NeoSeq combined with TMS is high.

[Analysis of clinical features, biochemical indices and genetic variants among children with Short/branched-chain acyl-CoA dehydrogenase deficiency detected by neonatal screening].

OBJECTIVE: To investigate the clinical manifestations, biochemical abnormalities and pathogenic variants among children with Short/branched-chain acyl-CoA dehydrogenase (SBCAD) deficiency detected by neonatal screening. METHODS: A total of 2 730 852 newborns were screened from January 2016 to December 2021 with liquid chromatography tandem mass spectrometry. Suspected SBCAD deficiency patients were diagnosed by urine organic acid analysis and high-throughput gene sequencing analysis. The clinical, biochemical and genetic changes of the confirmed cases were analyzed, in addition with guidance for diet and life management, L-carnitine supplement, and survey of growth and intellectual development. RESULTS: Twelve cases of SBCAD deficiency were diagnosed, which yielded a prevalence of 1/227 571. The lsovaleryl carnitine (C5) of primary screening blood samples was between 0.6 and 2.1 µmol/L, all exceeded the normal range. C5/acety1 carnitine (C2) was between 0.02 and 0.12, with 6 cases exceeding the normal range. C5/propionyl carnitine (C3) was between 0.1 and 1.16, with 5 cases exceeding the normal range. Free carnitine (C0) was between 18.89 and 58.12 µmol, with 1 case exceeding the normal range. Three neonates with abnormal screening results were recommended to have appropriate restriction for protein intake and two were given L-carnitine. During follow-up, their C5 has ranged from 0.22 to 2.32 µmol/L, C5/C2 has ranged from 0.01 to 0.31, C5/C3 has ranged from 0.14 to 1.7. C5 or C5/C2 and C5/C3 were transiently normal in all patients except for case 8 during the neonatal screening and follow-up. C0 was 17.42 ∼ 76.83 µmol/L Urine organic acid analysis was carried out in 9 of the 12 cases, and 2-methylbutyroglycine was elevated in 8 cases. Urine organic acid analysis was carried out in 9 cases, and 2-methylbutyrylglycine was increased in 8 cases. Genetic analysis was carried out for 11 children, and in total 6 ACADSB gene variants were identified, which included 4 missense variants (c.655G>A, c.923G>A, c.461G>A, c.1165A>G), 1 frameshift variant (c.746del) and 1 nonsense variant (c.275C>G). Among these, the C.461G>A variant was unreported previously. The most common variants were c.1165A>G (40.9%) and C.275C>G (22.7%). The patients were followed up for 18 days to 55 months. Only one patient had mental retardation, with the remainders having normal physical and mental development. CONCLUSION: SBCAD deficiency is a rare disease. The detection rate of newborn screening in this study was 1/227 571. Early intervention can be attained in most asymptomatic patients through neonatal screening. In this study, the common gene variants are c.1165A>G and c.275C>G.

[A prospective study of genetic screening of 2 060 neonates by high-throughput sequencing].

OBJECTIVE: To assess the value of genetic screening by high-throughput sequencing (HTS) for the early diagnosis of neonatal diseases. METHODS: A total of 2 060 neonates born at Ningbo Women and Children's Hospital from March to September 2021 were selected as the study subjects. All neonates had undergone conventional tandem mass spectrometry metabolite analysis and fluorescent immunoassay analysis. HTS was carried out to detect the definite pathogenic variant sites with high-frequency of 135 disease-related genes. Candidate variants were verified by Sanger sequencing or multiplex ligation-dependent probe amplification (MLPA). RESULTS: Among the 2 060 newborns, 31 were diagnosed with genetic diseases, 557 were found to be carriers, and 1 472 were negative. Among the 31 neonates, 5 had G6PD, 19 had hereditary non-syndromic deafness due to variants of GJB2, GJB3 and MT-RNR1 genes, 2 had PAH gene variants, 1 had GAA gene variants, 1 had SMN1 gene variants, 2 had MTTL1 gene variants, and 1 had GH1 gene variants. Clinically, 1 child had Spinal muscular atrophy (SMA), 1 had Glycogen storage disease II, 2 had congenital deafness, and 5 had G6PD deficiency. One mother was diagnosed with SMA. No patient was detected by conventional tandem mass spectrometry. Conventional fluorescence immunoassay had revealed 5 cases of G6PD deficiency (all positive by genetic screening) and 2 cases of hypothyroidism (identified as carriers). The most common variants identified in this region have involved DUOX2 (3.93%), ATP7B (2.48%), SLC26A4 (2.38%), GJB2 (2.33%), PAH (2.09%) and SLC22A5 genes (2.09%). CONCLUSION: Neonatal genetic screening has a wide range of detection and high detection rate, which can significantly improve the efficacy of newborn screening when combined with conventional screening and facilitate secondary prevention for the affected children, diagnosis of family members and genetic counseling for the carriers.

Progress of newborn screening in China. / 中国新生儿筛查进展.

Newborn screening (NBS) plays a significant role in reducing the risk of birth defects. NBS in China began in the early 1980s. Under the protection of laws and regulations and the leadership of the national health administration, approved screening centers in public hospitals took the responsibility for publicity, screening, diagnosis, treatment, follow-up and management of birth defects. As of 2022, 31 provinces (autonomous regions and municipalities directly under the central government) have carried out NBS for phenylketonuria, congenital hypothyroidism, and hearing loss, 23 provinces have carried out screening for glucose-6-phosphate dehydrogenase (with a screening rate of 89.24%), and 24 provinces have carried out screening for congenital adrenal cortical hyperplasia (91.45% screening rate). Over the past four decades, screening techniques have evolved from bacterial inhibition, fluorescence analysis, and tandem mass spectrometry for the detection of biochemical markers to genetic testing, which has greatly contributed to the expansion of the types of diseases screened for. The combined use of metabolomics and genomics is currently being explored. Effective management and rigorous quality control of NBS are prerequisites for improving the quality and ensuring the accuracy of screening. The Quality Management System for Newborn Screening System Network (QMS-NBS), established by the National Center for Clinical Laboratories, covers all screening centers and related blood collection agencies. The operation of the QMS-NBS allows the quality and performance of screening to be transparent and measurable, ensuring the quality and efficiency of screening. This article provides an overview of the history of NBS, especially the evolution of policies for the NBS in China, the construction of screening institutions, the number of newborns screened, the incidence rates of screened diseases, the changes in screening technology, the expansion of new diseases screened for, and the quality control of NBS. Overall, the progress in NBS in China has not only benefited from the development and standardization at the technological level, but also benefited from the construction of policies, regulations and ethics.

Results of neonatal screening for congenital hypothyroidism and hyperphenylalaninemia in Zhejiang province from 1999 to 2022. / 浙江省1200ä¸‡ä¾‹æ–°ç”Ÿå„¿å ˆå¤©æ€§ç”²çŠ¶è ºåŠŸèƒ½å‡é€€ç—‡ã€é«˜è‹¯ä¸™æ°¨é ¸è¡€ç—‡ç­›æŸ¥ç»“æžœåˆ†æž.

OBJECTIVES: To analyze the results of neonatal screening for congenital hypothyroidism (CH) and hyperphenylalaninemia (HPA) in Zhejiang province from 1999 to 2022. METHODS: A total of 11 922 318 newborns were screened from September 1999 and December 2022 in Zhejiang province. The blood thyroid stimulating hormone (TSH) levels were measured by a fluorescence method and blood phenylalanine (Phe) levels were measured by fluorescence method or tandem mass spectrometry. TSH≥9 µIU/mL was considered positive for CH, while Phe>120 µmol/L and/or Phe/Tyr ratio>2.0 were considered positive for HPA. The positive newborns in screening were recalled, and the gene variations were detected by high-throughput sequencing and MassARRAY tests. RESULTS: The overall neonatal screening rate during 1999-2022 was 89.41% (11 922 318/13 333 929) and the screening rate was increased from 6.46% in 1999 to 100.0% in 2022. A total of 8924 cases of CH were diagnosed among screened newborns with an incidence rate of 1/1336. A total of 563 cases of HPA were diagnosed, including 508 cases of classic phenylketonuria (cPKU) and 55 cases of tetrahydrobiopterin deficiency (BH4D), with an incidence rate of 1/21 176. Ninety-seven out of 8924 cases of CH underwent genetic analysis. Gene mutations were detected in 9 CH related genes, the highest frequency mutations were found in DUOX2 gene (69.0%) with c.3329G>A (p.R1110Q) (18.2%) and c.1588A>T (p.K530X) (17.3%) as the hotspot mutations. There were 81 PAH gene variants detected in a total of 250 cases of cPKU, and c728G>A (p.R243Q) (24.4%), c.721C>T (p.R241C) (15.0%) were the hotspot mutations. Meanwhile 7 novel variants in PAH gene were detected: c.107C>A (p.S36*), c.137G>T (p.G46V), c.148A>G(p.K50E), c.285C>T (p.I95I), c.843-10delTTCC, exon4-7del and c.1066-2A>G. There were 12 PTS gene variants detected in 36 cases of BH4D, and c.259C>T (p.P87S) (31.9%) was the hotspot mutation. CONCLUSIONS: The incident of CH has increased from 1999 to 2022 in Zhejiang province, and it is higher than that of national and global levels; while the incidence of HPA is similar to the national average. DUOX2 gene variation is the most common in CH patients; c.728G>A (p.R243Q) is the hotspot mutation in cPKU patients, while c.259C>T (p.P87S) is the hotspot mutation in BH4D patients.

Analysis of genotypes and biochemical phenotypes of neonates with abnormal metabolism of butyrylcarnitine. / ä¸é °åŸºè‚‰ç¢±ä»£è°¢å¼‚å¸¸æ–°ç”Ÿå„¿çš„åŸºå› åž‹å’Œç”ŸåŒ–è¡¨åž‹åˆ†æž.

OBJECTIVES: To investigate the genotypes and biochemical phenotypes of neonates with abnormal metabolism of butyrylcarnitine (C4). METHODS: One hundred and twenty neonates with increased C4 levels detected by tandem mass spectrometry in the neonatal screening at Children's Hospital, Zhejiang University School of Medicine from January 2018 to June 2023 were included. The initial screening data and recalled data of C4 and C4/C3 were collected and converted into multiples of C4 reference range. Next generation sequencing was performed and the exons with adjacent 50 bp regions of ACAD8 and ACADS genes were captured by liquid phase capture technique. Variant information was obtained by bioinformatic analysis and the pathogenicity were classified according to the American College of Medical Genetics and Genomics criteria. The Wilcoxon rank sum test was used to analyze the differences in C4 levels among neonates with different variation types. RESULTS: In total, 32 variants in ACAD8 gene were detected, of which 7 variants were reported for the first time; while 41 variants of ACADS gene were detected, of which 17 variants have not been previously reported. There were 39 cases with ACAD8 biallelic variations and 3 cases with ACAD8 monoallelic variations; 34 cases with ACADS biallelic variations and 36 cases with ACADS monoallelic variations. Furthermore, 5 cases were detected with both ACAD8 and ACADS gene variations. Inter group comparison showed that the multiples of C4 reference range in initial screening and re-examination of the ACAD8 biallelic variations and ACADS biallelic variations groups were significantly higher than those of the ACADS monoallelic variations group (all P<0.01), while the multiples in the ACAD8 biallelic variations group were significantly higher than those in the ACADS biallelic variations group (all P<0.01). The multiples of C4 reference range in the initial screening greater than 1.5 times were observed in all neonates carrying ACAD8 or ACADS biallelic variations, while only 25% (9/36) in neonates carrying ACADS monoallelic variations. CONCLUSIONS: ACAD8 and/or ACADS gene variants are the main genetic causes for elevated C4 in newborns in Zhejiang region with high genotypic heterogeneity. The C4 levels of neonates with biallelic variations are significantly higher than those of neonates with monoallelic variations. The cut-off value for C4 level could be modestly elevated, which could reduce the false positive rate in tandem mass spectrometry neonatal screening.

Long-term follow-up of children with carbamoyl phosphate synthase 1 deficiency detected in newborn screening. / æ–°ç”Ÿå„¿ç­›æŸ¥å‘çŽ°çš„æ°¨ç”²é °ç£·é ¸åˆæˆé ¶1ç¼ºä¹ç—‡æ‚£å„¿é•¿æœŸéšè®¿ç ”ç©¶.

OBJECTIVES: To investigate genotype-phenotype characteristics and long-term prognosis of neonatal carbamoyl phosphate synthetase 1 (CPS1) deficiency among children through newborn screening in Zhejiang province. METHODS: The clinical and follow-up data of children with CPS1 deficiency detected through neonatal screening and confirmed by tandem mass spectrometry and genetic testing in Zhejiang Province Newborn Disease Screening Center from September 2013 to August 2023 were retrospectively analyzed. RESULTS: A total of 4 056 755 newborns were screened and 6 cases of CPS1 deficiency were diagnosed through phenotypic and genetic testing. Ten different variations of CPS1 genewere identified in genetic testing, including 2 known pathogenic variations (c.2359C>T and c.1549+1G>T) and 8 unreported variations (c.3405-1G>T, c.2372C>T, c.1436C>T, c.2228T>C, c.2441G>A, c.3031G>A, c.3075T>C and c.390-403del). All patients had decreased citrulline levels (2.72-6.21 µmol/L), and varying degrees of elevated blood ammonia. The patients received restricted natural protein intake (special formula), arginine and supportive therapy after diagnosis, and were followed-up for a period ranging from 9 months to 10 years. Three patients experienced hyperammonemia, and one patient each had attention deficit hyperactivity disorder, transient facial twitching and increased muscle tone. One patient died, while the other five surviving patients had normal scores of the Ages & Stages Questionnaires (ASQ) and Griffiths Development Scales up to the present time; 4 cases had combined height or weight lag and one case was normal in height and weight. CONCLUSIONS: Low citrulline levels and hyperammonemia are common in CPS1 deficiency patients in Zhejiang. Most gene variants identified were specific to individual families, and no hotspot mutations were found. Early diagnosis through newborn screening and following standardized treatment can significantly improve the prognosis of the patients.

Complex I mutations synergize to worsen the phenotypic expression of Leber's hereditary optic neuropathy.

Leber's hereditary optic neuropathy (LHON) is a maternal inheritance of eye disease because of the mitochondrial DNA (mtDNA) mutations. We previously discovered a 3866T>C mutation within the gene for the ND1 subunit of complex I as possibly amplifying disease progression for patients bearing the disease-causing 11778G>A mutation within the gene for the ND4 subunit of complex I. However, whether and how the ND1 mutation exacerbates the ND4 mutation were unknown. In this report, we showed that four Chinese families bearing both m.3866T>C and m.11778G>A mutations exhibited higher penetrances of LHON than 6 Chinese pedigrees carrying only the m.3866T>C mutation or families harboring only the m.11778G>A mutation. The protein structure analysis revealed that the m.3866T>C (I187T) and m.11778G>A (R340H) mutations destabilized the specific interactions with other residues of ND1 and ND4, thereby altering the structure and function of complex I. Cellular data obtained using cybrids, constructed by transferring mitochondria from the Chinese families into mtDNA-less (ρ°) cells, demonstrated that the mutations perturbed the stability, assembly, and activity of complex I, leading to changes in mitochondrial ATP levels and membrane potential and increasing the production of reactive oxygen species. These mitochondrial dysfunctions promoted the apoptotic sensitivity of cells and decreased mitophagy. Cybrids bearing only the m.3866T>C mutation displayed mild mitochondrial dysfunctions, whereas those harboring both m.3866T>C and m.11778G>A mutations exhibited greater mitochondrial dysfunctions. These suggested that the m.3866T>C mutation acted in synergy with the m.11778G>A mutation, aggravating mitochondrial dysfunctions and contributing to higher penetrance of LHON in these families carrying both mtDNA mutations.

[Expert consensus for the diagnosis and treatment of glutaricacidemia type 1].

Glutaricacidemia type 1(GA1) is an autosomal recessive disease caused by reduced or missing glutaryl-CoA dehydrogenase activity which hamps metabolism of lysine, hydroxylysine and tryptophan. The catabolic products of glutarylcarnitine and glutaric acid are abnormally accumulated in the body, resulting in metabolic disorders which primarily lead to damage to the nervous system. Clinical manifestations of patients include macrocephaly, dystonia, dyskinesia, and developmental retardation. Acute encephalopathy may be induced in infants and young children due to infection, vaccination and surgery. For GA1 is a rare disease and its clinical manifestations are similar to other neurological diseases, it may be easily missed or misdiagnosed. To facilitate early diagnosis and treatment and improve the prognosis, this consensus was formulated by pediatric experts from the fields of endocrinology and genetic metabolism through full discussion and reference to the latest literature and guidelines home and abroad.

A case of methylmalonic acidemia and homocysteinemia cblX type with negative tandem mass spectrometry testing.

A child with methylmalonic acidemia and homocysteinemia cblX type presented focal seizures and epileptic spasms in early infancy, but the tandem mass spectrometry tests showed negative results during neonatal screening or acute attack. Despite treated with a variety of antiepileptic drugs, the child died at age of The blood spot sample of the patient was retrospectively tested with ultrahigh performance liquid chromatography-tandem mass spectrometry, and the increased levels of methylmalonic acid and homocysteine were revealed. Whole exome sequencing showed that the proband had a c.202C>G(p.Q68E) hemizygous mutation in gene, which was inherited from his mother.

Screening of multiple acyl-CoA dehydrogenase deficiency in newborns and follow-up of patients.

To investigate the incidence rate, clinical and gene mutation characteristics of multiple acyl-CoA dehydrogenase deficiency (MADD) in newborns in Zhejiang province. A total of 3 896 789 newborns were screened for MADD using tandem mass spectrometry in Zhejiang Neonatal Screening Center during January 2009 and December 2020. Patients of MADD were confirmed by urine organic acid and electron transferring flavoprotein (or electron transferring flavoprotein dehydrogenase () gene detection. MADD patients were given diet and life management, supplemented with L-carnitine, riboflavin and coenzyme Q 10 treatment, and their growth and intellectual development were evaluated during the followed up.Thirteen patients with MADD were diagnosed, with an incidence of 1/299 753. One patient was type Ⅱ, and the rest were type Ⅲ. Patients were followed up for 1 case died, 4 cases had acute metabolic disorders with hypoglycemia as the main manifestation due to infection, 1 case had hypotonia, and the rest 7 cases developed well. Patients had raised levels of C4-C18:1 acylcarnitines in the initial screening. Thirteen children were genetically tested, 1 case with compound heterozygous mutation in the gene, 1 case with homozygous mutation in the gene, 1 case with compound heterozygous mutation in the gene, 8 cases with compound heterozygous mutation and 1 case with homozygous mutation in the gene, 1 case that only 1 locus of gene was detected. The c.250G>A was the hotspot mutation in this study.The clinical manifestations of MADD are highly heterogeneous. The neonatal-onset form is serious, and late onset form usually has no obvious clinical symptoms. C4-C18:1 acylcarnitines usually increased in the initial screening, and the hotspot gene mutation is c.250G>A.

Application of genetic screening processor in screening neonatal glucose-6-phosphate dehydrogenase deficiency.

To evaluate the performance of genetic screening processor (GSP analyzer) in neonatal screening for glucose-6-phosphate dehydrogenase (G6PD)deficiency. The accuracy and precision of GSP analyzer was evaluated with the control materials from National Center for Clinical Laboratories and the low and high quality G6PD control kit (fluorescence analysis). GSP analyzer and semi-automatic fluorescence immunoanalyzer (1420 analyzer) were simultaneously used to detect 2622 neonatal screening samples and 41 confirmed samples to analyze the correlation and consistency of the test results; 78 floating samples and 78 non-floating samples were detected to compare the result. A total of 1 100 384 neonatal screening samples from January 2017 to December 2018 and 855 856 neonatal screening samples from January 2019 to December 2020 were detected with 1420 analyzer and GSP analyzer, respectively. Referring to the percentile method and the expert consensus, the new cut-off value of GSP analyzer for G6PD deficiency in screening was established. The relative bias of GSP analyzer in detecting G6PD was 0.71%-4.23%; the intra assay precision was 4.34%-4.91%, the inter assay precision was 0.85%-2.12%, and the total coefficient of variation was 5.44%-5.72%. There was a significant positive correlation between G6PD activity detected by GSP analyzer and 1420 analyzer (=0.740, <0.01). Forty-one clinical confirmed patients were identified by both 1420 analyzer and GSP analyzer (=0.945). The G6PD activity in floating dry blood spots detected by 1420 analyzer was significantly lower than that in non-floating dry blood spots (<0.05), but there was no significant difference in G6PD activity between floating and non-floating dry blood spots detected by GSP analyzer (>0.05). The sensitivities of GSP analyzer and 1420 analyzer in screening G6PD deficiency were both 100.00%, and the specificities were both more than 99.80%. Compared with 1420 analyzer, the positive predictive value, positive rate and prevalence of G6PD deficiency detected by GSP analyzer were increased, and the false positive rate was decreased (all <0.01). The new cut-off value was 26.1 U/dL for male and 29.1 U/dL for female according to the 99.1% percentile of the population. GSP analyzer has better detection performance with high automation, efficiency and throughput, which can be used in large-scale screening for neonatal G6PD deficiency.

[Phenotypic and genetic analysis of a child with multiple malformations due to 10p13p15.3 duplication].

OBJECTIVE: To explore the basis for a child with multiple malformations and correlate her genotype with phenotype. METHODS: The child was subjected to G-banding chromosomal analysis first, and low-coverage massively parallel copy number variation sequencing (CNV-seq) was used to define the aberrant region. The results were verified by fluorescence in situ hybridization (FISH). RESULTS: The child was found to have a karyotype of 46,XX,3pter+?. CNV-seq has identified a 13.5 Mb duplication at 10p13p15.3(60 466-13 556 655) and a 636 kb microdeletion at 3p26.3 (60 064-695 821). Her karyotype was the refore specified as 46, XX, ish der(3) t(3;10) (10p+,3pdim) by FISH. Both of her parents were normal, which suggested an de novo origin of the above variant. CONCLUSION: The de novo 10p13p15.3 duplication probably underlies the mental retardation, development delay, dysmorphism, and gastroesophageal reflux in the child. The CHL1 gene from the 3p26.3 region may play an important role in the formation and function of the brain, which may underlie the intellectual deficit in this child.

[Identification of a de novo missense variant of ARID1B gene in a child with mental retardation].

OBJECTIVE: To explore the genetic basis for a child with mental retardation. METHODS: The child was subjected to next generation sequencing (NGS). Candidate variant was analyzed with bioinformatic software. RESULTS: NGS revealed that the child has carried a de novo heterozygous c.4035G>C (p.Gln1345His) variant of the ARID1B gene. The variant was unreported previously and may cause instability of the protein structure. CONCLUSION: The de novo missense variant of ARID1B gene may underlie the mental retardation in the child. Above result has enabled genetic counseling and prenatal diagnosis for her family.

[Analysis of GFM1 gene mutations in a family with combined oxidative phosphorylation deficiency 1].

OBJECTIVE: To analyze the clinical phenotype and genetic characteristics of a family with combined oxidative phosphorylation deficiency 1 (COXPD-1). METHODS: The whole exome sequencing was performed in parents of the proband; and the genetic defects were verified by Sanger sequencing technology in the dried blood spot of the proband, the amniotic fluid sample of the little brother of proband, and the peripheral blood of the parents. RESULTS: Whole exome sequencing and Sanger validation showed compound heterozygous mutations of GFM1 gene c.688G>A(p.G230S) and c.1576C>T (p.R526X) in both the proband and her little brother, and the c.1576C>T of GFM1 variant was first reported. The two patients were died in early infancy, and presented with metabolic acidosis, high lactic acid, abnormal liver function, feeding difficulties, microcephaly, development retardation and epilepsy. CONCLUSIONS: GFM1 gene c.688G>A and c.1576C>T compound heterozygous mutations are the cause of this family of COXPD-1.

[Screening and clinical analysis of isovaleric acidemia newborn in Zhejiang province].

OBJECTIVE: To investigate the incidence,clinical,biochemical and genetic characteristics of isovaleric acidemia (IVA) in Zhejiang province. METHODS: Between January 2009 and December 2019, a total of 3 510 004 newborns were screened for IVA using tandem mass spectrometry. Patients of IVA were confirmed by urine organic acid and IVD gene detection. IVA patients were given diet and life management, supplemented with L-carnitine and glycine treatment, long-term followed up to observe and evaluate the growth and intellectual development. RESULTS: A total of 15 patients with IVA were diagnosed, with an incidence of 1/234 000. Three patients had acute neonatal IVA, and the rest were asymptomatic. The isovalerylcarnitine (C5) levels were increased in all patients. Twelve children underwent urinary organic acid analysis, of which 11 cases had elevated isovalerylglycine levels, 4 cases with 3-hydroxyisovalerate increased simultaneously. Eleven IVA patients underwent genetic testing, 9 patients were compound heterozygous variants in IVD gene, one with homozygous variants in IVD gene, and one harbored one IVD variant. Nineteen IVD variants (14 missense mutations, 3 intron mutations, 1 code shift mutation, and 1 synonymous mutation) were identified, 11 of which were not reported. Among the 15 IVA patients, one patient died and two patients were followed up locally. The remaining patients had no obvious clinical symptoms during the follow-up (2-79 months). Three patients presented with growth and development delay, the remaining had normal physical and mental development. CONCLUSIONS: The clinical manifestations of IVA are non-specific, and the gene spectrum is scattered. Newborn patients screened by tandem mass spectrometry can receive early diagnosis and treatment, so as to correct metabolic defects and pathophysiological changes.

[Effects of delivery and storage conditions on concentrations of amino acids and carnitines in neonatal dried blood spots].

OBJECTIVE: To explore effects of different delivery and storage conditions on concentrations of amino acids and carnitines in neonatal dried blood spots (DBS), so as to provide evidence for improving accurate and reliable detection by tandem mass spectrometry. METHODS: A total of 1 254 616 newborn DBS samples in Newborn Screening Center of Zhejiang Province were delivered and stored at room temperature (group A, n=338 467), delivered by cold-chain logistics system and stored at low temperature (group B, n=480 021), or delivered by cold-chain logistics system and stored at low temperature and low humidity (group C, n= 436 128), respectively. The concentrations of amino acids and carnitines in DBS were detected by tandem mass spectrometry. Data analysis was performed by SPSS 24.0 to explore the influence of temperature and humidity on the concentrations of amino acids and carnitines. RESULTS: The concentrations of amino acids and carnitines in the three groups were skewed, and the differences in amino acid and carnitine concentrations among groups were statistically significant (all P<0.01). The median concentration of tyrosine was lower in group A than those in group B and group C by 18%and 16%respectively, while there was no significant difference between the last two groups. The median concentrations of methionine were lower in group A and group B than that in group C by 15%and 11%, respectively. The median concentrations of arginine were lower in group A and group B than that in group C by 12%and 25%, respectively. The median concentration of free carnitine (C0) was higher in group A than that in group C by 12%, while there was no significant difference between group A and group B. The median concentrations of acetylcarnitine (C2), propionyl carnitine (C3), C3DC+C4OH, C5DC+C6OH and hexadecanoyl carnitine (C16) were lower in group A than those in group B and group C by 21%-64%. The concentrations of other amino acids and acylcarnitines differed little among three groups. The monthly median coefficients of variation of other amino acids and carnitines in group A were higher than those in group B and group C except for citrulline, C4DC+C5OH and isovalerylcarnitine (C5). CONCLUSIONS: Cold-chain logistics system and storage in low temperature and low humidity can effectively reduce degradation of some amino acids and carnitines in DBS, improve the accuracy and reliability of detection, and thus ensures the quality of screening for neonatal metabolic diseases.

[Analysis of ACADVL gene variations among nine neonates with very long chain acyl-coA dehydrogenase deficiency].

OBJECTIVE: To explore the clinical features and variations of ACADVL gene in 9 neonates with very long chain acyl-coenzyme A dehydrogenase deficiency (VLCADD). METHODS: VLCADD was suspected based on the results of neonatal screening by tandem mass spectrometry (MS-MS), with tetradecenoylcarnitine ± tetradecenoylcarnitine/octanoylcarnitine (C14: 1 ± C14: 1/C8) as the mark indexes. Infants with positive outcome were confirmed by sequencing of the ACADVL gene. RESULTS: Among 9 VLCADD cases, one case lost during follow-up, the observed phenotypes comprised 2 with severe early-onset form, 1 with hepatic form and 5 with late-onset form. Optimal outcome was acquired for all patients except the 2 early-onset cases. In total 16 ACADVL variations were detected among the 9 infants, which included 8 novel variations (c.96-105del GCCCGGCCCT, c.541C>T, c.863T>G, c.878+1G>C, c.895A>G, c.1238T>C, c.1276G>A, and c.1505T>A) and 11 missense variations. There were 9 genotypic combinations, including 1 homozygote and 8 compound heterozygotes. Except for two patients carrying null variations, all had a good outcome. CONCLUSION: VLCADD is relatively rare in southern China, for which late-onset form is common. Carriers of null variations of the ACADVL gene may have relatively poorer clinical outcome. Above results will provide valuable information for the diagnosis and management of VLCADD.

[Genetic analysis of newborns with abnormal metabolism of 3-hydroxyisovalerylcarnitine].

OBJECTIVE: To investigate the genetic characterization of 3-hydroxyisovalerylcarnitine (C5-OH) metabolic abnormality in neonates. METHODS: Fifty two newborns with increased C5-OH, C5-OH/C3 and C5-OH/C8 detected by tandem mass spectrometry during neonatal screening were enrolled in the study. Genomic DNA was extracted from the whole blood samples of 52 cases and their parents. Seventy-nine genes associated with genetic and metabolic diseases including MCCC1, MCCC2 were targeted by liquid capture technique. Variation information of these genes was examined by high-throughput sequencing and bioinformatic analysis, and then was classified based on the American College of Medical Genetics and Genomics (ACMG) standards and guidelines. The genetic types were classified as wild-type, MCCC1-maternal-mutation, MCCC1-paternal-mutation and MCCC2-mutation. Wilcoxon rank-sum test was performed for the increased multiples of C5-OH calculated in neonatal screening. RESULTS: Twenty one MCCC1 variants (14 novel) were identified in 37 cases, 6 MCCC2 variants (5 novel) in 4 cases. The increased multiple of C5-OH calculated in MCCC1-maternal-mutation and MCCC2-mutation groups were significantly higher than that in wild-type group (all P<0.05), while there was no significant difference between MCCC1-paternal-mutation group and wild-type group (P>0.05). CONCLUSIONS: Mutations on MCCC1 and MCCC2 genes are the major genetic causes for the increased C5-OH in neonates, and maternal single heterozygous mutation can contribute to the moderately to severely increased C5-OH.

[Screening for hereditary tyrosinemia and genotype analysis in newborns].

OBJECTIVE: To analyze the results of screening for hereditary tyrosinemia (HT) in newborns and its clinical features and genotype. METHODS: The HT screening was conducted among 2 188 784 newborns from November 2013 to November 2018. The tyrosine (TYR)/ succinylacetone (SA) levels were detected by tandem mass spectrometry (MS-MS). The clinical characteristics, genetic results and following up data of identified patients were analyzed. RESULTS: The normal ranges (0.5%-95.5%) of TYR and SA were 34.5-280.0 µmol/L and 0.16-2.58 µmol/L, respectively. Three HT cases were confirmed with a detection rate of 1∶729 595. There was 1 case of tyrosinemia type Ⅰ (HTⅠ) (homozygous variations of c.455G>A in FAH gene), 1 case of tyrosinemia type Ⅱ(HTⅡ) (heterozygous variations of c.890G>T and c.408+1G>A in TAT gene), and 1 case of tyrosinemia type Ⅲ (HT Ⅲ) (homozygous variations of c.257T>C in HPD gene). The variations of c.890G>T, c.4081G>A of TAT and c.257T>C of HPD were novel. The positive predictive value of the screening was 3.4%. Case 1 (HTⅠ) with TYR and SA values of 666.9 µmol/L and 3.87 µmol/L respectively, presented cholestasis, mild elevated of liver enzyme and lactic acid, who were although fed with TYR and phenylalanine free milk, but died at 2 months of age. Case 2 (HTⅡ) with higher TYR (625.6 µmol/L) and normal SA at screening, received medical milk treatment; during the 7 months of follow-up the baby showed normal score of Bayley assessment and normal TYR without eye and skin symptoms. Case 3 (HT Ⅲ) with TYR of 1035.3 µmol/L and normal SA at screening; during the 29 months of follow-up the value of TYR fluctuated from 532.1 µmol/L to 1060.3 µmol/L due to irregular medical milk treatment, while the score of Bayley assessment was normal. CONCLUSIONS: HT is rare in the southern Chinese population, and the gene spectrum is scattered. Early treatment with nitisinone is recommended in children with HTⅠ, otherwise the prognosis is poor; the prognosis of children with HTⅡ is good when early treated with special diet; the prognosis of children with HTⅢ needs to be determined with more data.