Expert consensus on screening, diagnosis and treatment of multiple carboxylase deficiency / 浙江大学学报·医学版

Multiple carboxylase deficiency (MCD) includes autosomal recessive holocarboxylase synthetase (HLCS) deficiency and biotinidase (BTD) deficiency, which are caused by and gene mutations respectively. Neonatal screening for HLCS deficiency is based on 3-hydroxyisovaleryl carnitine in dry blood filter paper, and BTD deficiency is based on BTD activity determination. HLCS deficiency and BTD deficiency are characterized by neurocutaneous syndrome and organic aciduria, however, they are different in onset age, neurological symptoms and metabolic decompensation, which needed to be differentiated from acquired biotin deficiency or other genetic metabolic diseases. The diagnosis of the disease requires a combination of biochemical characteristics of hematuria, enzyme activity determination and genetic test. Routine biotin doses are effective for most MCD patients. This consensus is intended to benefit early screening and diagnosis of MCD.

Gene variant analysis of a patient with multiple carboxylase deficiency / 中华医学遗传学杂志

OBJECTIVE@#To explore the genetic basis for a patient featuring multiple carboxylase deficiency (MCD).@*METHODS@#PCR and Sanger sequencing were used to detect variant in the coding region of BT and HLCS genes in the patient. Suspected variants were verified in her parents and 80 unrelated healthy controls by a PCR-restriction fragment length polymorphism (PCR-RFLP) method.@*RESULTS@#The patient was found to carry compound heterozygous variants of the HLCS gene, namely c.286delG (p.Val96Leufs*162) and c.1648G>A (p.Val550Met). The c.286delG (p.Val96Leufs*162) was verified to be novel variant based on the result of PCR-RFLP analysis. No variant was found in the coding regions of BT gene in the patient.@*CONCLUSION@#The compound c.286delG (p.Val96Leufs*162) and c.1648G>A (p.Val550Met) variants probably underlie the MCD disorder in this patient. Above results have enriched the variant spectrum of MCA.

Construction of recombinant strains co-expressing PPK and GMAS for the synthesis of L-theanine / 生物工程学报

Recombinant strains expressing enzymes for ATP regeneration and L-theanine production were constructed and used for the synthesis of L-theanine. The ppk gene encoding polyphosphate kinase (PPK) from Rhodobacter sphaeroides and gmas gene encoding γ-glutamylmethylamide synthetase (GMAS) from Methylovorus mays were synthesized, and two recombinant plasmids, pETDuet-ppk+gmas and pET21a-ppk+gmas were constructed for co-expression of PPK and GMAS in Escherichia coli BL21(DE3). SDS-PAGE analysis showed that PPK and GMAS were overexpressed in soluble form in both recombinant strains. GMAS-PPK obtained from the recombinant strain containing pET21a-ppk+gmas was more efficient to synthesize L-theanine. After 24 h at 37 ℃ and pH at 7.0, 86.0% yield of L-theanine was achieved with catalytic amount of ATP. This study extends the application of enzymatic ATP regeneration system. In addition, it provides an efficient method for the biosynthesis of L-theanine.

Application of methylation-specific multiplex ligation-dependent probe amplification for the study of DNA methylation in placenta tissues / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the feasibility of using methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) for the detection of DNA methylation in placenta tissue.</p><p><b>METHODS</b>For blood cells from 13 non-pregnant women and 9 euploid placenta, the ratios of DNA methylation were evaluated for 4 genes including CGI149, CGI113, HLCS and ACTB with MS-MLPA and bisulfite sequencing, respectively.</p><p><b>RESULTS</b>The methylation ratio of the ACTB gene was 0-0.1 for the blood cells when the digestion control was completely digested. The cutoff value for the methylation ratio of MS-MLPA has been determined as 0.1. For the 9 placenta samples, results of MS-MLPA and bisulfite sequencing were concordant for all of the four genes.</p><p><b>CONCLUSION</b>MS-MLPA is an effective alternative to bisulfite sequencing for the assessment of methylation ratios in placental tissues.</p>

Gene mutation analyses in Chinese children with multiple carboxylase deficiency / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To confirm the diagnosis of multiple carboxylase deficiency (MCD) on the gene level and explore the mutations in Chinese children with MCD.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

Diagnosis, treatment and gene mutation analysis in children with holocarboxylase synthetas deficiency / 中国当代儿科杂志

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSIONS</b>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.</p>

Improved expression of HLA-A* 2402-BSP in Escherichia coli and its tetramer preparation / 生物工程学报

HLA-A* 2402 is one of the most frequently encountered HLA-A alleles in East Asian populations. In order to study the CD8+ T cell responses in Chinese populations, we have described the generation and functional test of HLA-A* 2402 tetramer loaded with HCMV pp65(341-349) peptide (QYDPVAALF, QYD). The cDNA of HLA-A* 2402 heavy chain was cloned by RT-PCR from one of the donors. DNA fragment encoding the ectodomain of HLA-A* 2402 heavy chain fused at its carboxyl-terminal a BirA substrate peptide (BSP) was amplified by PCR with the cloned heavy chain cDNA as a template. The wild-type gene of HLA-A* 2402-BSP was not expressed in Escherichia coli (E. coli), while mutant HLA-A* 2402-BSP gene with optimized codons was overexpressed as inclusion bodies in E. coli. Furthermore, the soluble HLA-A* 2402-QYD monomers were generated by in vitro refolding of washed inclusion bodies in the presence of beta2-microglobulin and QYD peptide. The tetramer was subsequently formed by mixing HLA-A* 2402-QYD monomers with streptavidin-PE at a molar ratio of 4:1. Flow cytometry analysis indicated that this tetramer possessed binding activity with specific CTL from HLA-A24+ donors and the frequencies of tetramer-binding CTL were 0.09% - 0.37% within total CD8+ T cells. This tetrameric agent provides a powerful tool to explore the secrets of CTL responses against HCMV antigens in HLA-A* 2402 individuals.

Gene mutation analysis in four Chinese patients with multiple carboxylase deficiency / 中华儿科杂志

<p><b>OBJECTIVE</b>Multiple carboxylase deficiency (MCD) is an autosomal recessive disorder. MCD is characterized by skin rash, metabolic acidosis, vomiting and psychomotor retardation. Depending on deficiency of the enzyme, MCD includes two different forms, biotinidase deficiency (BTD, OMIM 253260) and holocarboxylase synthetase deficiency (HLCSD, OMIM 253270). In this study, we analyzed gene mutations of four Chinese MCD patients and to explore the mutation spectrum and possibility of a molecular diagnosis.</p><p><b>METHODS</b>All exons and their flanking introns of biotinidase gene and HLCS gene were screened by polymerase chain reaction combined with DNA direct sequencing in four Chinese MCD patients. Genomic DNA was extracted using a kit from the peripheral blood leukocytes of each patient. PCR amplification products were checked by 2% agarose gel electrophoresis and were subsequently sequenced with both the forward and reverse primers.</p><p><b>RESULTS</b>All patients showed mutations in HLCS gene, whereas no mutation was found in biotinidase gene, proving that all the four patients had HLCS deficiency. Four previously reported mutations in HLCS gene were detected (Y456C, R508W, D634N and 780delG). A missense mutation of 1522C > T in exon 11 of HLCS gene, which was a homozygotic mutation, was identified in patient 1; a mutation of 1522C > T in exon 11 combined with a mutation of 1367A > G in exon 9, which was a compound heterozygotic mutation, was identified in patient 2; a mutation of 1522C > T in exon 11 combined with a mutation of 1900G > A in exon 13, which was a compound heterozygotic mutation, was identified in patient 3; a mutation of 1522C > T in exon 11 combined with a mutation of 780delG in exon 7, which was a compound heterozygotic mutation, was identified in patient 4. All the parents were carriers of mutations. No additional carrier of this four mutations was identified from 50 samples of Chinese controls.</p><p><b>CONCLUSION</b>The 1522C > T (R508W) mutation probably represents a mutational hot-spot in Chinese HLCS deficiency patients while the 780delG mutation which was reported only in Japanese patients was found firstly in Chinese patients.</p>

Cloning and expression of HLA-A*0201-BSP / 中国实验血液学杂志

High-yield production of HLA-A*0201 heavy chain is a prerequisite to the preparation of HLA-A2 tetramer. The present study was aimed to construct the expression vector of recombinant HLA-A*0201-BSP fusion gene for preparing HLA-A2 tetramers. The extracellular region HLA*0201 was cloned by RT-PCR from HLA-A2(+) donor, and a 15-amino acid biotin-protein ligase (BirA) substrate peptide (BSP) for BirA-dependent biotinylation was added to the COOH-terminus of HLA-A*0201 heavy chain. Then the fusion gene was cloned into pBV220 vector at EcoRI and Bam HI sites and its sequence was confirmed by DNA sequence analysis. The recombinant plasmid pBV220-HLA-A*0201-BSP was transformed to the competent cells of E.coli DH5alpha. The results showed that the HLA-A*0201-BSP fusion protein was successfully expressed in the form of inclusion body and amounted to over 28% of total cell proteins via induction at 42 degrees C. After washed with triton X-100 and urea, the inclusion body was dissolved with 8 mol/L urea and then purified with Sepharcyl S-300 HR, and the final purity reached above 90%. It is concluded that the HLA-A*0201-BSP fusion gene was cloned successfully and expressed efficiently in E.coli DH5alpha. This work establishes a convenient approach for purification of large quantity of recombinant HLA-A*0201-BSP. This provides the basis for the preparation of HLA-A2 tetramers.

Effect of C: N ratio on numbers and types of fungi in Egyptian soil.

The amendment of three different soil types [loamy, clay and sandy] with different carbon sources [glucose, cellulose, starch, chitin and sawdust] increased the total count of fungi compared with non-amended soil. Treatment with chitin increased the densities of Trichoderma harzianum. Testing the effect of different C: N ratios [5: 1, 10: 1 and 40: 1] on soil fungi in a loamy soil sample using glucose or cellulose and NaNO3 showed that a narrow C: N ratio was more stimulative to the development of the fungal flora in the presence of glucose. However, a wide C: N ratio was more favorable when cellulose was used as a carbon source showing that sugar fungi and cellulose decomposers responded differentially. Trichoderma was favored by a wide C: N ratio [40: 1] using either glucose or cellulose as a carbon source