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The patient was a 21 days-old baby girl,admitted to Guangdong Women and Children Hospital because of "poor intake,seldom crying and no activity in 1 day".The major clinical manifestations included hypotonia,aggravation of the conscious disturbance,pancytopenia,intractable acidosis and hyperammonemia,so,inherited metabolic disorders should be considered.Screening of inherited metabolic diseases with blood and urine samples,genetic test and active treatments were carried out.After targeted next-generation sequencing,a novel homozygotic frame shift mutation in PCCB gene:c.838_839insC (L280Pfs * 11) was identified,which was validated by Sanger sequencing.This mutation had not been reported in the mutation database,and bioinformatic analysis of this mutation indicated disease-causing.So,the diagnosis of propionic acidemia was identified.The baby was in a critical condition,and despite active treatment,her conscious disturbance was aggravated,and the spontaneous breathing disappeared.Subsequently,the baby died of pneumonia.Propionic acidemia is a relatively common genetic metabolic disease in newborns.The severity and the clinical phenotypes of propionic acidemia varied,which often made the diagnosis difficult.When the baby is presented with developmental delay,hypotonia,recurrent convulsion and vomiting,etc,which can't be explained by common diseases of children,propionic acidemia may be considered.Next generation sequencing analysis of the complicated cases can easily to pinpoint a disease-causing gene,which lays a solid foundation for accurate diagnosis and treatment of the patients.

Objective To study the characteristics of hyperphenylalaninemia (HPA) and the differences in blood and urine metabolic index and their correlation.Methods A total of 137 patients with HPA diagnosed by the Pediatric Inherit Metabolism and Endocrine Department,Guangdong Women and Children's Hospital,Guangzhou Medical University from January 2014 to June 2017,were enrolled.Tandem mass spectrometry (MS/MS),gas chromatography/ mass spectrometry (GC-MS) and high performance liquid chromatography (HPLC) were used to analyze the concentration of blood and urine metabolites in children,and the patients were divided into different groups according to the drug load test of tetrahydrobiopterin (BH4) and dihydrobiopterindine reductase (DHPR) deficiency.The HPA metabolite analysis of horizontal concentration by statistical differences and correlation analysis were performed.Results Among the 137 cases of HPA,there were 101 cases (73.7％) of phenylalanine hydroxylase deficiency (PAH),and among them 21 cases (15.3％) were classic phenylketonuria (PKU),37 cases were mild PKU (27.0％),43 cases (31.4％) wcrc mild HPA.Thcrc were 22 cases (16.1％) with BH4 reaction,and 79 cases (57.7％) of non-reactive type.Besides,there were 36 cases (26.3％) of tetrahydrobiopterin deficiency (BH4 D),of which 6-pyruvoyl tetrahydropterin synthase deficiency (PTPS) in 34 cases (24.8％) and dihydrobiopterindine reductase deficiency (DHPR) in 2 cases (1.5％).Urinary phenylacetic acid (r =0.673,P ＜ 0.01),phenyllactic acid (r =0.736,P ＜ 0.01),phenylpyruvic acid (r =0.642,P ＜ 0.01) were significantly correlated with blood phenylalanine (Phe) concentration,and the neopterin (N) (r =0.442,P ＜ 0.01) and biopterin (B) (r =0.398,P ＜ 0.01) had low correlation.Urinary phenylacetic acid,phenyllactic acid and phenylpyruvic acid had no correlation with urinary pterin.There were significant differences among PTPS deficiency group,BH4 response type,and non-reactive type(all P ＜ 0.05),but no significant difference between the BH4 reaction type and the non-reactive group (P ＞ 0.05).Conclusions Through the analysis of the different types of HPA metabolic profiles,it can help to master the incidence and characteristics in the region,within a certain concentration range of blood Phe,the phenylacetic acid,phenyllactic acid,phenylpyruvic acid should not be tested by GC-MS alone.Uterine erythropoietin analysis of BH4D classification and identification of BH4 reaction,non-reactive PKU have a supporting role,so master the metabolic index of various types of concentration and relevance of HPA,it can provide basis for early diagnosis,accurate treatment and follow-up.