Identification of predominant GNPTAB gene mutations in Eastern Chinese patients with mucolipidosis II/III and a prenatal diagnosis of mucolipidosis II.

Mucolipidosis II α/ß, mucolipidosis III α/ß, and mucolipidosis III γ are autosomal recessive disorders belonging to the family of lysosomal storage disorders caused by deficiency of the UDP-N-acetylglucosamine, a lysosomal enzyme N-acetylglucosamine-1-phosphotransferase (GlcNAc-phosphotransferase) localized in the Golgi apparatus, which is essential for normal processing and packaging of soluble lysosomal enzymes with initiating the first step of tagging lysosomal enzymes with mannose-6-phosphate (M6P). Mucolipidosis II and III are caused by mutations in the GNPTAB and GNPTG genes, and patients with these diseases are characterized by short stature, skeletal abnormalities, and developmental delay. In this study we report 38 patients with mucolipidosis II and III enrolled in Eastern China during the past 8 years. The diagnosis was made based on clinical characteristics and measurement of plasma lysosomal enzyme activity. Sanger sequencing of GNPTAB and/or GNPTG for all patients and real-time quantitative PCR were performed to confirm the diagnosis. In addition, 11 cases of prenatal mucolipidosis II were diagnosed based on measurement of the enzyme activity in amniotic fluid supernatant and genetic testing of cultured amniotic cells. Based on molecular genetic tests, 30 patients were diagnosed with mucolipidosis II α/ß, 6 were diagnosed with III α/ß and 2 were diagnosed with III γ. Thirty-seven different GNPTAB gene mutations were identified in 29 patients with mucolipidosis II α/ß and six patients with III α/ß. These mutations included 22 new mutations (p.W44X, p.E279X, p.W416X, p.W463X, p.Q802X, p.Q882X, p.A34P, p.R334P, p.D408N, p.D534N, p.Y997C, p.D1018V, p.L1025S, p.L1033P, c.88_89delAC, c.890_891insT, c.1150_1151insTTA, c.1523delG, c.2473_2474insA, c.2980_2983delGCCT, c.3094delA, and deletion of exon 9). Four new GNPTG gene mutations were identified (c.13delC, p.Y81X, p.G126R and c.609+1delG) in two mucolipidosis III γ patients. Among the 11 cases of prenatal diagnosis, four were mucolipidosis II fetuses, three were heterozygous, and the remaining four were normal fetuses. This study expands the mutation spectrum of the GNPTAB and GNPTG genes and contributes to specific knowledge of mucolipidosis II/III in a population from Eastern China.

Factors associated with unplanned extubation in the Intensive Care Unit for adult patients: A systematic review and meta-analysis.

OBJECTIVES: To explore factors associated with unplanned extubation in Intensive Care Unit for adult patients. RESEARCH METHODOLOGY: A systematic review and meta-analysis were performed of studies identified through Pubmed, CINAHL, Cochrane Library, PsycINFO and Web of Science published from initiation to September 2017. Only articles in English were included. The Newcastle-Ottawa Scale was used to evaluate the quality of the included articles. RESULTS: Ten eligible studies were identified, encompassing a total of 2092 patients (457 in the unplanned extubation group; 1635 in the control group). The subsequent meta-analysis identified significant risk factors for unplanned extubation are male [odds ratio (OR) 1.54, 95% CI 1.12-2.12; P = 0.008], confusion [OR 0.10, 95% CI 0.05-0.17; P < 0.00001], physical restraint [OR 3.10, 95% CI 2.21-4.34; P < 0.00001], higher GCS scores [mean difference (MD) 1.06, 95% CI 0.59-1.52; P < 0.00001] and lower APACHE II scores [MD -2.26, 95% CI -3.35- -1.16; P < 0.0001]. Renal disease is a protective factor for unplanned extubation [OR 0.32, 95% CI 0.15-0.70; P = 0.004]. CONCLUSION: Patients were male, confused, having physical restraint, with higher GCS and lower APACHE II scores are significant risk factors for unplanned extubation in Intensive Care Unit adult patients.

Eight novel mutations in the ABCD1 gene and clinical characteristics of 25 Chinese patients with X-linked adrenoleukodystrophy.

BACKGROUND: X-linked adrenoleukodystrophy (X-ALD) is a fatal neurodegenerative disease caused by mutations in the adenosine triphosphate-binding cassette D1 (ABCD1) gene. This study aimed to retrospectively investigate the clinical characteristics of 25 patients with X-ALD including members of large pedigrees, to analyze ABCD1 gene mutations, the effect of gene novel variants on ALD protein (ALDP) structure and function, and to expand gene mutation spectrum of Chinese patients. METHODS: Twenty-five male patients diagnosed with X-ALD were enrolled in this study. The clinical characteristics of the patients were retrospectively summarized by reviewing medical records or telephone consultation. ABCD1 gene mutations were analyzed. The pathogenicity of novel missense variants was analyzed using cobalt constraint-based multiple protein alignment tool, polymorphism phenotyping, sorting intolerant from tolerant, Align-Grantham variation and Grantham deviation, and Swiss-Program Database Viewer 4.04 software, respectively. RESULTS: Childhood cerebral form ALD (CCALD) is the most common phenotype (64%) in the 25 patients with X-ALD. The progressive deterioration of neurological and cognitive functions is the main clinical feature. The demyelination of the brain white matter and elevated plasma very long chain fatty acids (VLCFAs) were found in all patients. Different phenotypes were also presented within family members of the patients. Twenty-two different mutations including 8 novel mutations in the ABCD1 gene were identified in the 25 patients. Of the mutations, 63.6% were missense mutations and 34.8% located in exon 1. The amino acid residues of three novel missense mutations in eight species were highly conserved, and were predicted to be "probably" damaging to ALDP function. The other five novel mutations were splice, nonsense, deletion or duplication mutations. CONCLUSIONS: CCALD is the most common phenotype (64%) in our patients with X-ALD. Eight novel mutations in the ABCD1 gene identified are disease-causing mutations. Brain magnetic resonance imaging and plasma VLCFA determination should be performed for the patients who present with progressive deterioration of neurological development.

[Clinical and mutational features of maternal 3-methylcrotonyl coenzyme deficiency].

OBJECTIVE: To report on 5 patients with maternal 3-methylcrotonyl coenzyme A carboxylase deficiency (MCCD) and to confirm the clinical diagnosis through mutation analysis. METHODS: Five neonates with higher blood 3-hydroxy isovalerylcarnitine (C5-OH) concentration detected upon newborn screening with tandem mass spectrometry and their mothers were recruited. Urinary organic acids were analyzed with gas chromatography mass spectrometry. Gene mutation and protein function analysis were performed by PCR direct sequencing and PolyPhen-2 software. RESULTS: Higher blood C5-OH concentrations (5.11-21.77 µmol/L) and abnormal 3-hydroxy isovalerate and 3-methylcrotonyl glycine in urine were detected in the five asymptomatic mothers, who were diagnosed as benign MCCD. Higher C5-OH concentration was also detected in their neonates by tandem mass spectrometry, which had gradually decreased to normal levels in three neonates. Four new variations, i.e., c.ins1680A(25%), c.203C > T (p.A68V), c.572T > C (p.L191P) and c.639+5G > T were detected in the MCCC1 gene, in addition with 2 mutations [c.1406G > T (p.R469L, novel variation) and c.592C > T (p.Q198X)]. The novel variations were predicted to have affected protein structure and function. CONCLUSION: For neonates with higher C5-OH concentration detected upon neonatal screening, their mothers should be also tested to rule out MCCD. Mutations in MCCC1 gene are quite common.

[Diagnosis and treatment of isolated methylmalonic acidemia].

OBJECTIVE: To explore the clinical feature, therapeutic effect and prognosis of isolated methylmalonic acidemia. METHODS: The clinical characteristics, laboratory findings, treatment and outcome of 40 patients were retrospectively analyzed. The main treatment was a low-protein diet supplemented with L-carnitine and special milk free of leucine, valine, threonine and methionine. Vitamin B12 was also given to cobalamin responders. The patients were followed up every 1-3 months. RESULTS: Mutations in the MUT gene were identified in 30 of 33 patients who had accepted DNA testing. Thirty cases were treated and followed up regularly for from 1 month to 8 years. Eight cases had died, 8 had developed normal intelligence, among whom 4 from newborn screening were asymptomatic. Psychomotor developmental delay and mental retardation were present in 14 cases. The propionylcarnitine level, ratio of propionylcarnitine/acetylcarnitine in blood, methylmalonic acid and methylcitric acid levels in urine have decreased significantly, with the median values reduced respectively from 24.15 (7.92-81.02) µmol/L, 1.08 (0.38-6.01), 705.34 (113.79-3078.60) and 7.71 (0.52-128.21) to 10.50 (3.00-30.92) µmol/L, 0.63 (0.25-2.89), 166.23 (22.40-3322.21) and 3.96 (0.94-119.13) (P < 0.05). CONCLUSION: The prognosis of isolated methylmalonic acidemia may be predicted with the enzymatic subgroup, age at onset and cobalamin responsiveness. Outcome is unfavorable in neonatal patients and those who were non-responsive to cobalamin.

[Outcomes of patients with combined methylmalonic acidemia and homocystinuria after treatment].

OBJECTIVE: Combined methylmalonic acidemia with homocystinuria is a common form of methylmalonic acidemia in China. Patients with this disease can progress to death without timely and effective treatment. This study aimed to analyze the treatment outcomes of patients with combined methylmalonic acidemia and homocystinuria. METHOD: From September 2004 to April 2012, 58 patients with combined methylmalonic acidemia and homocystinuria (34 males and 24 females) were diagnosed and treated in our hospital. Fifty cases were from clinical patients including 42 early-onset cases and 8 late-onset cases. Their age when they were diagnosed ranged from 18 days to 30.8 years. The other 8 cases were from newborn screening. All the patients were treated with vitamin B12, betaine, folic acid, vitamin B6, and L-carnitine. The physical and neuropsychological development, general laboratory tests, the levels of amino acids, acylcarnitines, and homocysteine in blood, and organic acids in urine were followed up. RESULT: The follow-up period ranged from 1 month to 7.1 years. Three cases died (all were early-onset cases). In the other patients after treatment, the symptoms such as recurrent vomiting, seizures, lethargy, and poor feeding disappeared, muscle strength and muscle tension were improved, and general biochemical abnormalities such as anemia and metabolic acidosis were corrected. Among the surviving 55 cases, 49 had neurological impairments such as developmental delay and mental retardation. The median levels of blood propionylcarnitine and its ratio with acetylcarnitine, serum homocysteine, and urine methylmalonic acid were significantly decreased (P < 0.01), from 7.73 µmol/L (ranged from 1.5 to 18.61 µmol/L), 0.74 (ranged from 0.29 to 2.06), 97.3 µmol/L (ranged from 25.1 to 250 µmol/L) and 168.55 (ranged from 3.66 to 1032.82) before treatment to 2.74 µmol/L (ranged from 0.47 to 12.09 µmol/L), 0.16 (ranged from 0.03 to 0.62), 43.8 µmol/L (ranged from 17 to 97.8 µmol/L) and 6.81 (ranged from 0 to 95.43) after treatment, respectively. CONCLUSION: Patients with combined methylmalonic acidemia and homocystinuria respond to a combined treatment consisting of supplementation of hydroxycobalamin, betaine, folic acid, vitamin B6 and L-carnitine with clinical and biochemical improvement. But the long-term outcomes are unsatisfactory, with neurological sequelae in most patients.

[Analysis of propionylcarnitine in blood and methylmalonic acid in urine of 162 patients with methylmalonic acidemia].

OBJECTIVE: To analyze the levels of methylmalonic acid and methylcitrate in urine, propionylcarnitine (C3) in plasma and C3/acetylcarnitine (C2) of patients with methylmalonic acidemia (MMA) and explore their applications in the diagnosis of MMA. METHODS: From December 2003 to March 2012, a total of 162 patients with MMA (MMA group) and 200 healthy children (control group) of Xinhua Hospital, Shanghai Jiaotong University School of Medicine were recruited. MMA patients with a definite classification were divided into 2 groups: isolate MMA group (n = 51) and MMA complicated with homocysteinemia group (n = 65). Gas chromatography-mass spectrometry was used to measure the urine levels of methylmalonic acid and methylcitrate and tandem mass spectrometry to measure the blood levels of free carnitine (C0), acylcarnitines and methionine (Met). RESULTS: In the MMA group, the median levels of methylmalonic acid (259.10 (6.73 - 6429.28)), methylcitrate (4.39 (0 - 248.96)), C3 (8.52 (1.50 - 52.11) µmol/L) and C3/C2 (0.73(0.28 - 2.89)) were all higher than the upper limit values (0.2 - 3.6, 0 - 1.1, 0.50 - 4.00 µmol/L and 0.04 - 0.25 respectively). And they were all higher than those in the control group (0 (0 - 1.87), 0.10 (0 - 1.84), 1.40 (0.53 - 3.90) µmol/L, 0.10 (0.04 - 0.23), all P < 0.01). C3/C2 increased significantly in 15 patients while the C3 level remained normal. The median level of Met was normal in the isolate MMA group. But in patients with homocysteinemia, the level of 8.71 (0.68 - 31.95) µmol/L was below the reference value (10.00 - 35.00 µmol/L) and lower than that in the isolate MMA group (15.35 (4.18 - 59.50) µmol/L) and the control group (15.59 (10.20 - 34.68) µmol/L, all P < 0.05). CONCLUSIONS: Significant increases in the urine level of methylmalonic acid and C3/C2 may be specific to MMA. Organic acid analyses of gas chromatography-mass spectrometry and acylcarnitines with tandem mass spectrometry are required for a definite diagnosis of this disorder. And repeated tests and genomic mutation analysis are necessary for patients with mildly abnormal biochemical indices.

[Primary carnitine deficiency in 17 patients: diagnosis, treatment and follow up].

OBJECTIVE: Many children were found to have low free carnitine level in blood by tandem mass spectrometry technology. In some of the cases the problems occurred secondary to malnutrition, organic acidemia and other fatty acid oxidation metabolic diseases, and some of cases had primary carnitine deficiency (PCD). In the present article, we discuss the diagnosis of PCD and evaluate the efficacy of carnitine in the treatment of PCD. METHOD: We measured the free carnitine (C0) and acylcarnitine levels in the blood of 270 000 neonates from newborns screening program and 12 000 children with suspected clinical inherited metabolic diseases by tandem mass spectrometry. The mutations of carnitine transporter protein were tested to the children with low C0 level and the diagnosis was made. The children with PCD were treated with 100 - 300 mg/kg of carnitine. RESULT: Seventeen children were diagnosed with PCD, 6 from newborn screening program and 11 from clinical patients. Mutations were found in all of them. The average C0 level [(2.9 ± 2.0) µmol/L] in patients was lower than the reference value (10 µmol/L), along with decreased level of different acylcarnitines. The clinical manifestations were diverse. For the 6 patients from newborn screening, 4 were asymptomatic, 1 showed hypoglycaemia and 1 showed movement intolerance from 2 years of age. For the 11 clinical patients, 8 showed hepatomegaly, 7 showed myasthenia, 6 showed cardiomyopathy, 1 showed chronic abdominal pain, and 1 showed restlessness and learning difficulty. Among these patients, 14 cases were treated with carnitine. Their clinical symptoms disappeared 1 to 3 months later. The C0 level in the blood rose to normal, with the average from (4.0 ± 2.7) µmol/L to (20.6 ± 8.3) µmol/L (P < 0.01). However, the level was still lower than the average level of healthy children [(27.1 ± 4.5) µmol/L, P < 0.01]. CONCLUSION: Seventeen patients were diagnosed with PCD by the test levels of free carnitine and acylcarnitines in blood with tandem mass spectrometry, and gene mutation test. Large dose of carnitine had a good effect in treatment of the PCD patients.

[Application of succinylacetone levels measurement in the blood and urine in the diagnosis of tyrosinemia type 1].

OBJECTIVE: To establish the diagnostic method of tyrosinemia type 1 and evaluate its value, the succinylacetone levels in the blood of suspected patients with tyrosinemia were tested by tandem mass spectrometry, and the succinylacetone in the urine was tested by gas chromatography-mass spectrometry. METHOD: A total of 190 patients suspected of having tyrosinemia, were tested by tandem mass spectrometry for measurement of the level of succinylacetone in the blood, and detected by gas chromatography-mass spectrometry for measurement of the level of succinylacetone and organic acid in the urine. The method of measuring the level of succinylacetone in blood by tandem mass spectrometry as follows: After the diameter of 3 mm dry blood spots were punched into wells of 96-well plate, 100 µl 80% acetonitrile were added into each well, which contained hydrazine monohydrate and the internal standard of succinylacetone. The supernatant fluid were transferred to another 96-well plate and dried under heated nitrogen, after the plate was incubated for 30 min at 65°C. The residual hydrazine reagent was removed by addition of 100 µl methanol to each well and evaporated under heated nitrogen. The mobile phase (80% acetonitrile) was added to each well and 20 µl samples were tested by tandem mass spectrometry. The diagnostic terms were the clinical manifestation and the high level of succinylacetone in both blood and urine. RESULT: Eleven patients were diagnosed as tyrosinemia type 1, with 9 males and 2 females. Their ages ranged from 2 months to 6 years. The succinylacetone levels in the blood of the patients were remarkably increased (7.26-31.09 µmol/L), with an average of (14.2 ± 7.8)µmol/L. Seven patients were tested for the level of succinylacetone in the urine by gas chromatography-mass spectrometry, and 4 were positive and 3 negative. Their tyrosine levels in the blood were 190-543 µmol/L(Normal: 20 - 100 µmol/L), with an average of (327.3 ± 125.8) µmol/L. All the patients presented the symptoms of hepatomegaly. Among them, 9 patients died and 2 patients were improved after treatment. CONCLUSION: The higher levels of succinylacetone in the blood or urine is a remarkable evidence for the diagnosis of tyrosinemia type 1. Determination of succinylacetone in the dry blood spots using tandem mass spectrometry was a good method for diagnosis of tyrosinemia type 1. To test succinylacetone in urine by gas chromatography-mass spectrometry may yield a false-negative result for tyrosinemia type 1.

[Clinical characteristics and analysis of mass spectrometric data in 33 patients with maple syrup urine disease].

OBJECTIVE: To explore the clinical characteristics and the diagnostic method of maple syrup urine disease (MSUD). METHODS: From January 2003 to December 2011, a total of 14 000 patients with suspected inherited metabolism diseases were tested. The blood levels of leucine and valine of these patients were detected by tandem mass spectrometry. The urinary level of branched-chain α-ketoacids was tested by gas chromatography-mass spectrometry. And the diagnosis was based on the elevated levels of leucine and valine in blood and branched-chain α-ketoacids in urine. RESULTS: Thirty-three MSUD patients were confirmed. Their median age of initial visit was 0.17 years old (range: 7 days to 30 years old). The peak onset age of them was 2-30 days old, including 28 cases of neonatal onset (84.8%). The presenting symptoms of 28 cases were feeding difficulties (n=14), poor response, lethargy and seizures. Their median blood levels of leucine and valine (1901 (458-5804) and 600 (315-1617) µmol/L) were significantly higher than their normal levels ((50-300) and (60-250) µmol/L, both P<0.01). Their urinary levels of 2-OH-isovaleric acid, 2-keto-isovaleric acid, 2-keto-3-methylvaleric acid, 2-keto-isocaproic and acetylglycine (262.5 (5.4-624.3), 35.8 (1.9-156.0), 133.8 (7.4-611.5), 518.7 (17.2-2121.2) and 280.5 (11.0-1087.9) respectively) significantly higher than their normal levels (0, <0.1, 0, 0, <0.1 respectively, all P<0.01). In 5 intermittent MSUD patients, their blood levels of leucine and valine (402 (348-958) and 556 (322-808) µmol/L) were significantly higher than their normal levels (both P<0.01). The urinary level of 2-OH-isovaleric acid was significantly higher than its normal levels (P<0.01) while the urinary levels of other α-ketoacids were normal. CONCLUSIONS: The confirmation of MSUD remains difficult because of a lack of specific clinical features. The detections of tandem mass spectrometry and gas chromatography-mass spectrometry may aid its early diagnosis.

[Studies on the clinical manifestation and SLC25A13 gene mutation of Chinese patients with neonatal intrahepatic cholestasis caused by citrin deficiency].

OBJECTIVE: To investigate the clinical and laboratory features of neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) and to characterize the molecular basis and prognosis of this disease. METHODS: Twenty-six patients with NICCD were collected because of idiopathic intrahepatic cholestasis and jaundice. The diagnosis was made by routine laboratory data collection, tandem mass spectrometry (MS-MS) and gas chromatography mass spectrometry (GC-MS) analyses. SLC25A13 gene mutation was analyzed by using polymerase chain reaction (PCR), direct DNA sequencing and restriction fragment length polymorphism analyses. The patients were followed up for nearly 2 years. RESULTS: The NICCD patients showed low birth weight and the average onset of jaundice was 29 days. Laboratory data showed liver dysfunction, hyperbilirubinemia, hypoproteinemia, high levels of alpha-fetoprotein, prolonged prothrombin time, hypoglycemia and hyperammonemia. MS-MS analysis of the blood samples revealed specific elevation of citrulline, methionine, threonine, tyrosine and elevation of free carnitine, short-chain and long-chain acylcarnitines. GC-MS analysis of the urine samples showed elevated 4-hydroxyl phenyllactic acid and 4-hydroxyl phenylpyruvic acid. Twelve different mutations were identified, including 4 novel mutations, i.e., G386V, R467X, K453R and 1192-1193delT. Forty-four mutated alleles were identified in the 52 alleles (84.6% ). Among them, 851del4, 1638ins23 and IVS6+5G>A mutations were the most frequent mutations, accounting for 40.9%, 20.5% and 11.4% of the total alleles examined respectively. Five of the 26 patients have not been recovered, including 4 died and 1 accepted liver transplantation. No obvious relationship was found between the genotype and phenotype in NICCD. CONCLUSION: The 851del4, 1638ins23 and IVS6+5G>A mutations are the hot-spot mutations in Chinese NICCD patients. Some NICCD patients have poor prognosis.

[Gene mutation analyses in Chinese children with multiple carboxylase deficiency].

OBJECTIVE: To confirm the diagnosis of multiple carboxylase deficiency (MCD) on the gene level and explore the mutations in Chinese children with MCD. METHODS: Biotinidase (BT) and holocarboxylase synthetase (HLCS) genes were analyzed by PCR and direct sequencing for the 4 BT deficiency patients and 8 HLCS deficiency patients, respectively. The identified mutations in the parents of the patients and 50 normal controls were screened by PCR-restriction fragment length polymorphism and direct DNA sequencing. RESULTS: Total detection rate of gene mutation is 100% in the 12 children with MCD. Six mutations were detected in the 4 children with BT deficiency, they were c. 98-104del7ins3, c. 1369G>A (V457M), c. 1157G>A(W386X), c. 1284C>A(Y428X), c. 1384delA and c. 1493_1494insT. The last four were novel mutations. Four mutations were found in the 8 children with HLCS deficiency. They were c. 126G>T (E42D), c. 1994G>C (R665P), c. 1088T>A (V363D) and c. 1522C>T (R508W). The last two were hot-spot mutations [75%(12/16)], and c. 1994G>C (R665P) was a novel mutation. CONCLUSION: This study confirmed the diagnosis of 12 patients with MCD on the gene level. Six mutations were found in the BT gene and 4 in the HLCS gene, including 5 novel mutations. Two mutations of the HLCS gene are probably hot-spot mutations in Chinese children with HLCS deficiency.

[Diagnosis, treatment and gene mutation analysis in children with holocarboxylase synthetas deficiency].

OBJECTIVE: To report the clinical diagnosis, treatment and follow-up of children with holocarboxylase synthetas(HCS) deficiency and explore the gene mutation spectrum of the disease. METHODS: Eleven children with HCS deficiency were enrolled. Mass spectrometry analysis and biotinidase activity determination were used for diagnosis of HCS deficiency. HCS gene mutations were analyzed by PCR directed sequencing methods. Ten patients received oral biotin treatment (10-40 mg/d). Clinical effects of biotin treatment were observed. RESULTS: All 11 cases developed apathetic, lethargy and metabolic acidosis at different degrees, and 10 cases presented with skin lesions. The average blood 3-hydroxyisovaleryl-carnitine concentrations and urinary 3-methylcrontonylglycine and methylcitrate concentrations increased significantly. The biotinidase activity increased, being higher over 30% of the normal reference value. Four mutations in HCS gene were identified, and they were c.1522C>T (R508W), c.1088T>A (V363D), c.126G>T (E42D) and c.1994G>C (R665P) (a new variant) and the frequency was 50%, 29%, 7% and 14% respectively. The symptoms disappeared in 10 cases 1-2 weeks after biotin treatment, and blood and urinary abnormal metabolites were gradually reduced to normal 2-6 months after treatment. CONCLUSIONS: HCS deficiency is characterized by nervous system damage, skin lesions and metabolic acidosis. Mass spectrometry analysis, biotinidase activity determination and gene mutation analysis may be helpful in the definite diagnosis of this disorder. The effect of early biotin treatment is satisfactory. The mutations R508W and V363D might be hot-spots in Chinese children with HCS deficiency.

[Analysis of gene mutations in Chinese patients with methylmalonic acidemia and homocysteinemia].

OBJECTIVE: Methylmalonic acidemia complicated with homocysteinemia, cblC type, is the most common inborn error of cobalamin metabolism. The gene MMACHC (OMIM 277400) is located on chromosome 1p34.1 with four coding exons and a 5th non-coding exon. It encodes for a protein with 282 amino acid residues. So far, more than 40 mutations have been detected, in which 271dupA (R91KfsX14) is the hot spot of MMACHC gene. However, there have not been relevant reports in China. The present study aimed to identify the mutation types of MMACHC gene and analyze the genotype-phenotype correlations in Chinese patients. METHOD: The diagnosis of this disease mainly depends on the measurement of C3 propionylcarnitine, C3/C0 (free carnitine) and C3/C2 (acetylcarnitine) in the blood by tandem mass spectrometry, the detection of methylmalonic acid in the urine by gas-chromatography mass spectrometry, the determination of total homocysteine in the serum, and the loading test of vitamin B12. The entire coding region of MMACHC gene was screened by polymerase chain reaction (PCR) combined with DNA direct sequencing in 28 Chinese patients. Genomic DNA was extracted using phenol-chloroform method from the peripheral blood leukocytes of each patient. PCR amplification products were checked by 1.8% agarose gel electrophoresis and were subsequently sequenced with both the forward and reverse primers. Mutational analyses were performed using normal human genomic MMACHC sequence as a reference (GenBank ID: 25974). RESULT: In this study, ten mutations were identified in 27 of 28 Chinese patients. Most of them were located in exons 3 and 4 (91.3%). We detected four mutations reported, which were 609G>A (W203X), 217C>T (R73X), 271dupA (R91KfsX14), and 394C>T (R132X), and six novel mutations, which were 1A>G, 365A>T, 658_660delAAG, 301-3_327del 30, 567_568insT, and 625_626insT. The 609G>A (W203X) is the most common mutation, which was detected in 30 of 56 alleles (53.6%), including 10 homozygote mutations and 10 heterozygote mutations. In addition, three gene polymorphisms were detected, namely, -302T>G (rs3748643), -234A>G (rs3728644), and 321G>A (rs2275276). These mutations include missense mutations, nonsense mutations, duplication, deletions, and insertions. CONCLUSION: In this study, we found a part of gene mutations spectrum in Chinese patients with methylmalonic acidemia and homocysteinemia, in which the 609G>A (W203X) may be the hotspot mutation of MMACHC gene. This would be helpful in the prenatal diagnosis and gene screening programs of methylmalonic acidemia and homocystinemia.

[Enzymatic diagnosis of 47 cases with mucopolysaccharidosis].

OBJECTIVE: With the emergence of enzyme replacement therapy and progress in bone marrow transplantation, treatment of mucopolysaccharidosis (MPS) is much more promising than ever. In order to benefit from these therapies, determination of the defective enzyme is the prerequisite for any individual patient. To make definite diagnosis for patients suspected of having MPS clinically, the authors established six lysosomal enzymatic assays for leucocytes, including alpha-L-iduronidase, iduronate-2-sulfatase, N-acetylgalactosamine 6-sulfatase, beta-galactosidase, arylsulfatase B, beta-glucuronidase, which are the corresponding enzymes of type I, type II, type IVA, type IVB, type VI, and type VII, respectively. METHOD: Seventy patients suspected of having MPS were enrolled from outpatient clinics of the Department of Pediatric Endocrinologic, Genetic and Metabolic Diseases in Xinhua Hospital. Their ages spanned from 10 months to 25 years with the average age 5.7 years. Of them 49 were male and 21 were female. Leukocytes were isolated with Dextran from peripheral blood of suspected patients. Activity of leukocyte alpha-L-iduronidase, iduronate-2-sulfatase, N-acetylgalactosamine 6-sulfatase, beta-galactosidase, beta-glucuronidase were measured using their specific artificial fluorescent substrates, while arylsulfatase B were determined by colorimetric assay with dipotassium 2-hydroxy-5-nitrophenyl sulfate as the substrate. RESULT: Of the 70 clinically suspected cases totally 47 were confirmed of having mucopolysaccharidosis, of whom 7 cases were type I, 28 cases type II, 12 cases type IVA. These data show that type II is the predominant form of MPS in China, succeeded by MPS type IVA. It was also noted that type II has the most variable clinical manifestations and 8 out of 12 type IVA patients had the unique lax joints. CONCLUSION: The present study suggest that type II might be the predominant form of MPS cases in China, followed by type IVA and type I.

[The investigation of differential diagnostic development and incidence of tetrahydrobiopterin deficiency].

OBJECTIVE: To investigate the development of differential diagnosis of tetrahydrobiopterin (BH4) deficiency among patients with hyperphenylalaninemia (HPA) in provinces or cities of China and to investigate the incidence of BH4 deficiency. METHODS: Of the thirteen hundreds and ninety-two patients with HPA received, the differential diagnosis for BH4 deficiency during 1993 - 2007 were enrolled in this study. Of which, 591 patients came from outpatient and 801 patients' samples from other provinces or cities were sent to author's laboratory to investigate the case number of differential diagnosis for BH4 deficiency in provinces or cities of China according to the data from both outpatient case histories and laboratory as to investigating the development of differential diagnosis in the whole country. To discuss the diagnostic criteria for BH4 deficiency was according to the results of urinary pterin analysis, determination of dihydropteridine reductase (DHPR) activity and the tetrahydrobiopterin loading test as well as to get the incidence of BH4 deficiency and find some provinces or cities with higher incidence of BH4 deficiency in China. RESULTS: (1) The number of HPA patients, who were performed by urinary pterin analysis and the determination of DHPR activity, were remarkably increased in last three years (2005 - 2007). The patient numbers of both urinary pterin analysis and DHPR activity determination were 217 and 198 respectively in 2005. And in 2007 they increased to 511 and 458, which was about 2.3 times than that in 2005. The patients came from 29 provinces or cities in 2007. (2) The urinary biopterin and biopterin percent were key marks for diagnosis of 6-pyruvoyl tetrahydropterin synthase (PTPS) deficiency. The less than 5% [(1.41 +/- 1.10)%] biopterin percent and very low biopterin level [(0.14 +/- 0.17) mmol/mol Cr] were found in 96.83% (61/63) patients with PTPS deficiency in this study. The blood phenylalanine level was remarkably decreased to normal range at 2 - 6 hours after BH4 loading test. The very low DHPR activity was a final diagnostic mark for DHPR deficiency. The very low DHPR activities of 0.27 nmol/(min x 5 mm disc) (6.11% - 7.00% of normal controls) were found in two patients with DHPR deficiency in this study. (3) The incidences of PTPS deficiency and DHPR deficiency among 1392 patients with hyperphenylalaninemia were 8.41% (117/1392) and 0.18% (2/1108) respectively. About 67.23% (80/119) patients with BH4 deficiency came from the south of Yangtze liver. The 80% (8/10) provinces or cities with higher incidence of BH4 deficiency are located in eastern and southern China. The incidence of PTPS deficiency among patients with HPA and normal newborns was 10.81% (8/74) and 0.007 per thousand (8/1,121,429) respectively in Shanghai, China according to data from neonatal screening. CONCLUSION: The awareness of differential diagnosis for BH4 deficiency from clinic pediatricians has been increased in most provinces or cities of China in last three years, but it should be more strengthened.

[A study on the active efflux system in methicillin-resistant Staphylococcus aureus].

OBJECTIVE: To explore the status of methicillin-resistant Staphylococcus aureus (MRSA) infection in an intensive care unit (ICU), and investigate the active efflux mechanism of MRSA. METHODS: Eighty isolates were identified as MRSA among 102 strains of Staphylococcus aureus collected, and then the minimal inhibitory concentration (MIC) were determined. The 4 primers of active efflux gene were designed to amplify the 80 clinical isolates respectively by polymerase chain reaction (PCR). The PCR products were analyzed by electrophoresis in order to grasp the situation of the existence of the four genes (norA, qacA, qacB and qacJ). Omeprazole inhibition test was used to observe the changes in the susceptibility of MRSA to antibiotics. RESULTS: The detection rate of MRSA was 78.4%. The sensitivity rate of MRSA to both vancomycin and teicoplanin was 100.0%, while to other antibiotics (oxacillin, benzylpenicillin, cefuroxime, cefotaxime, ceftazidime, ceftiaxone, cefepime, cefoxitin, imipenem, piperacillin and tazobactam, azithromycin, erythromycin, chloramphenicol, clindamycin, amikacin, gentamicin, levofloxacin, gatifloxacin, ciprofloxacin) MRSA was multi-drug resistant. The detection rates of norA, qacA, qacB and qacJ were 67.5% (54/80), 15.0% (12/80), 21.2% (17/80) and 11.2% (9/80), respectively. Combined use of omeprazole and levofloxacin could lower MIC value. CONCLUSION: The infection of MRSA in ICU is serious. MRSA is multi-drug resistant and possesses active efflux genes norA, qacA, qacB and qacJ. Omeprazole can inhibit the activity of the active efflux genes.

[Diagnosis of inborn errors of metabolism using tandem mass spectrometry and gas chromatography mass spectrometry].

OBJECTIVE: To investigate the effects of tandem mass spectrometry (MS/MS) combined with gas chromatography mass spectrometry (GC-MS) in the diagnosis of inborn errors of metabolism in children. METHODS: Amino acids and acylcarnitines in the dry blood filter papers were tested by MS/MS, and the organic acid profiles in urea were tested by GC-MS among 4981 children suspected to be with inborn errors of metabolism from more than 100 hospitals in China. A few pediatric patients underwent analysis of activity of enzyme and gene mutation analysis too. RESULTS: 319 of the 4981 children (6.4%) were diagnosed as with 24 kinds of diseases: 155 of the 319 cases (48.6%) with 8 kinds of amino acid diseases (97 with hyperphenylalaninemia, 14 with maple syrup urine disease 13 with ornithine transcarbamylase deficiency, 13 with citrullinemia type II, 10 with tyrosinemia type I, 5 with citrullinemia type I, 2 with homocystinuria, and 1 with arginasemia); 150 of the 319 cases (47.0%) were diagnosed as with 10 kinds of organic acidemias (81 with methylmalonic acidemia, 17 with propionic acidemia, 17 with multiple CoA carboxylase deficiency, 11 with glutaric acidemia type II, 8 with isovaleric acidemia, 6 with beta-keto thiolase deficiency, 5 with 3-methylcrotonyl-CoA carboxylase deficiency, and 3 with 3-hydroxy-3-methylglutaryl-CoA lyase deficiency); 14 cases (4.4%) were diagnosed as with 6 kinds of fatty acid disorders (5 with medium chain acyl-CoA dehydrogenase deficiency, 3 with very long chain acyl CoA dehydrogenase deficiency, 2 with short chain acyl-CoA dehydrogenase deficiency, 2 with multiple acyl-CoA dehydrogenase deficiency, 1 with carnitine palmitoyl transferase type II, and 1 with carnitine palmitoyl transferase type I). CONCLUSION: MS/MS is specific for amino acid diseases and fatty acid disorders. GC-MS is specific for detect organic acidemias. And the diagnoses of part of amino acid diseases need the combination of both methods.

[Diagnosis, treatment and gene mutation analysis of the first case with dihydropteridine reductase deficiency in the mainland of China].

OBJECTIVE: The 6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency is the most common type of tetrahydrobiopterin (BH4) deficiency. The reported patients with BH4 deficiency are all PTPS deficient found in the mainland of China previously. The activity of dihydropteridine reductase in BH4 metabolism has been determined for 902 patients with hyperphenylalaninemia in the authors' laboratory since 2003. The purposes of this study were to characterize the first case with DHPR deficiency who was diagnosed in June, 2007, to investigate the clinical manifestation, the differential diagnostic criteria, the effect of treatment as well as gene mutation of DHPR deficiency. METHODS: (1) A male patient presented with poor hand control, seizure, hypotonia and mental retardation since five-month after birth. His phenylalanine (Phe) level was 600 micromol/L and he was diagnosed as hyperphenylalaninemia at the age of one year and six-month. (2) This patient was subjected to combined Phe (100 mg/kg) and BH4 (20 mg/kg) loading test, to evaluate the degree of Phe level response to BH4. Urinary neopterin and biopterin analysis as well as the determination of DHPR activity in dried blood spot were also performed. (3) The blood DNA samples of the patient and his parents were collected to amplify the seven exons of QDPR gene using related primers, and the amplified products were directly sequenced for mutation analysis. (4) The patient was treated with BH4 or with a combined small amount of Phe-free special milk, neurotransmitter precursors and folic acid after the diagnosis and was followed up for clinical effects of treatment. RESULTS: (1) The basic Phe level was 476 micromol/L, then it increased to 1355 micromol/L at 3 h after taking Phe and slowly decreased to 610 micromol/L at 24h after taking BH4. (2) The basic urinary neopterin and biopterin were 2.92 mmol/mol Cr (normally < 2.61 mmol/mol Cr) and 7.44 mmol/molCr (normally < 2.67 mmol/mol Cr) respectively, and biopterin percentage was 71.79% (normally 42.7% - 75.9%). The patient had higher biopterin level. (3) The DHPR activity of this patient was (0.27 - 0.51) nmol/(min.5 mm disc) which were 6.11% - 10.6% of normal control, so he was diagnosed as DHPR deficiency. (4) The analysis of QDPR gene mutation showed that the patient carries missense mutation c.515C > T (P172L) from his father and nonsense mutation c.661C > T (R221X) from his mother. The c.515C > T is not reported before, we also did not find this mutation in 50 normal children. (5) The patient started to be treated with large dosage of BH4 (10 - 20) mg/(kg.d) or BH4 combined with small amounts of Phe-free milk, neurotransmitter precursors L-dopa (3 - 5) mg/(kg.d) plus carbidopa, 5-hydroxytryptophan (3 - 5) mg/(kg.d), and folic acid 15 mg/d as well at the age of one year and six-month after the diagnosis. The seizure has disappeared, the symptoms such as hypotonia have been obviously improved and the Phe level was 60 micromol/L at the six months after the treatment in this patient. CONCLUSION: (1) The patient with DHPR deficiency has common symptoms of BH4 deficiency (such as fair hair, hypotonia, mental retardation), and there is metabolic disturbance of folic acid in DHPR deficiency. (2) The higher Phe levels slowly decreased after BH4 loading test, the urinary biopterin level was very high and the DHPR activity was very low in the patient with DHPR deficiency. (3) The c.515C > T may be a new mutation of QDPR gene. (4) The DHPR deficient patient must be treated with higher dose of BH4 (8 - 20) mg/(kg.d), neurotransmitter precursors and folic acid as well.

[Gene mutation analysis in patients with propionic acidemia].

OBJECTIVE: Propionic acidemia is a common organic acidemia, caused by deficiency of propionyl-CoA carboxylase (PCC), which catalyzes the carboxylation of propionyl-CoA to D-methylmalonyl-CoA. PCC is a dodecameric enzyme of alpha-PCC and beta-PCC subunits, nuclearly encoded by genes PCCA and PCCB, respectively. Mutation in either gene cause propionic acidemia, the PCCA gene is located on chromosome 13q32 with 24 exons and the PCCB gene is located on chromosome 3q13.2-q22 with 15 exons. In this study, we analyzed gene mutations of 11 PCCA and PCCB deficient patients from China and to explore the possible mutation spectrum. METHODS: All 39 exons of PCCA and PCCB genes in 11 unrelated Chinese PA patients were analyzed by polymerase chain reaction (PCR) and direct sequencing. Genomic DNA was extracted using phenol-chloroform method from the peripheral blood leukocytes of each patient. PCR amplification products were checked by 1.8% agarose gel electrophoresis and were subsequently sequenced with ABI 3700 Automated DNA Sequencer. RESULTS: The authors identified 13 PA mutations, 8 affecting the PCCA gene, 5 affecting the PCCB gene, including 10 novel mutations and 3 previously reported mutations. Three missense mutations (1079T > G, 1102G > C and 1850T > C), one splicing mutation (716-2A > G) and one short deletion (1863delA) were found in alpha-PCC subunit while three missense mutations (484G > A, 601G > A and 1253C > T) and two short insertion-deletions (167-179del13ins1, 560-561delCCinsT) were found in beta-PCC subunit. The 167-179del13ins1 change was identified in two homozygous PA patients, with allelic frequency of 40% in beta-PCC subunit deficiencies. CONCLUSION: Thirteen mutations were found in 11 Chinese PA patients including ten novel mutations. No mutation is predominant in Chinese PCCA and PCCB deficient patients.