Female ; Humans ; Infant ; Metabolism, Inborn Errors ; Methylmalonic Acid ; blood

Amino Acid Metabolism, Inborn Errors ; blood ; diagnosis ; Female ; Humans ; Infant ; Methylmalonic Acid ; blood

To evaluate the implication of methymalonic acid (MMA) in the early diagnosis of neural tube defects (NTD), a quantitative assay for MMA was established by using gas chromatography-mass spectrometry with stable isotope of MMA as an internal standard. Amniotic fluid and maternal urine MMA concentration, maternal serum folate, red blood cell folate and vitamin B12 levels were measured in the middle term of NTD-affected and normal pregnancies. Amniotic fluid and maternal urine MMA concentrations in the middle term of NTD affected pregnancies (1.4 +/- 0.9 micromol/L, and 22.1 +/- 12.6 nmol/micromol creatinine) were significantly higher than that of normal pregnancies (1.0 +/- 0. 4 micromol/L, and 2.5 +/- 1.1 nmol/micromol creatinine). There was no significant difference between normal and NTD pregnancies for serum folate, red blood cell folate and vitamin B12 levels. The results suggested that MMAs in amniotic fluid and maternal urine are sensitive markers for early diagnosis of NTD. Vitamin B12 is an active cofactor involved in the remethylation of homocycteine and its deficiency is an independent risk factor for NTD. MMA is a specific and sensitive marker for intracellular vitamin B12 deficiency. This study suggests that it is necessary to monitor the vitamin B12 deficiency and advocates vitamin B12 supplementation with folate prevention program.
Amniotic Fluid/*chemistry ; Biological Markers/analysis ; Biological Markers/urine ; Folic Acid/blood ; Methylmalonic Acid/analysis ; Methylmalonic Acid/*urine ; Neural Tube Defects/*diagnosis ; Neural Tube Defects/metabolism ; Pregnancy Trimester, Second ; *Prenatal Diagnosis ; Vitamin B 12/blood

Methylmalonic acidemia (MMA) is a heterogeneous inborn error of propionate metabolism and its management frequently includes a low-protein diet to minimize precursors of methylmalonic acid and reduce its concentration in body tissues. In the long- term follow-up, renal dysfunction in these patients has been increasingly recognized. Tubulointerstitial nephritis is the most frequent renal complications and has been reported in the small number of renal biopsy specimens from young children previously by others. We report a case of a 18-year-old girl with MMA and renal dysfunction in whom renal biopsy demonstrated chronic tubulointerstitial nephritis.
Adolescent ; Biopsy ; Child ; Diet, Protein-Restricted ; Diethylpropion ; Female ; Follow-Up Studies ; Humans ; Metabolism ; Methylmalonic Acid ; Nephritis, Interstitial*

OBJECTIVETo investigate the MUT gene mutations in patients with methylmalonic acidemia (MMA), and analyze the genotype-phenotype correlation in patients with methylmalonyl-CoA mutase deficiency.

METHODSThe diagnosis of the disease mainly depends on the measurement of C3 (acylcarnitine), 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 B(12). The entire coding region of the MUT gene was screened by PCR combined with direct DNA sequencing in 21 isolated MMA patients. Novel mutations were identified by restriction fragment length polymorphism (RFLP) and sequence analysis in 100 controls.

RESULTSSeventeen MUT gene mutations were detected in 14 of the 21 patients, among them 8 mutations were novel, and R108H, D244LfsX39 and G544X were more frequent, with the frequencies of 9.5%, 7.1% and 9.5%, respectively. Most mutations were missense mutations (64.7%), and majority of them were in exons 2 and 3 (55.6%). Ten out of the 14 patients with MUT gene mutations had early-onset disease, while one case had late-onset disease, and the remaining 3 cases were detected by newborn screening. In addition, 11 of these 14 patients did not respond to vitamin B(12).

CONCLUSIONThis study revealed partial MUT gene mutation spectrum in Chinese patients with isolated MMA. The patients carrying MUT mutations often had early-onset disease, and most of them were VitB(12)- non-responsive.

Amino Acid Metabolism, Inborn Errors ; genetics ; Base Sequence ; China ; Female ; Humans ; Infant ; Infant, Newborn ; Male ; Methylmalonic Acid ; metabolism ; Methylmalonyl-CoA Mutase ; genetics ; Molecular Sequence Data ; Mutation

OBJECTIVEMethylmalonic 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.

METHODThe 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).

RESULTIn 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.

CONCLUSIONIn 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.

Amino Acid Metabolism, Inborn Errors ; complications ; genetics ; Cysteine ; blood ; DNA ; DNA Mutational Analysis ; Exons ; Humans ; Hyperhomocysteinemia ; complications ; genetics ; Methylmalonic Acid ; blood ; Mutation

OBJECTIVECblC is the most common type of methylmalonic acidemia with homocysteinemia. MMACHC is the coding gene. This study aimed at understanding clinical features and gene mutations in 2 Chinese pedigrees who had late-onset methylmalonic acidemia complicated with homocysteinemia.

METHODThe clinical data of 2 cases were analyzed. The MMACHC gene mutation was detected using polymerase chain reaction (PCR) and DNA sequencing.

RESULTThe age of onset was 13 years and 12 years, respectively. They both presented with nervous system symptoms. The main clinical features were developmental retardation and degradation, including motion, speech and intelligence. One patient complained of anemia. The other patient was misdiagnosed as having a viral encephalitis. Both patients showed remarkable elevation of methylmalonic acid and homocysteine levels in urine. Both had received therapy with vitamin B(12). The symptoms were rapidly relieved. The follow-up till now showed apparent improvement in the 2 cases. Three mutations in the MMACHC gene were found in the two Chinese pedigrees. Both patients were compound heterozygotes of two mutant alleles: one patient had a G-to-A transition at nucleotide 482 (G482A) that caused an arginine-to-glutamine substitution at position 161 of the protein (R161Q), and a deletion of AAG at nucleotide 658_660 (658_660delAAG) which resulted in lysine deleting at position 220 of the protein (K220del); the other patient had a G482A and a G-to-A transition at nucleotide 609 (G609A) that caused a tryptophan-to-termination codon substitution at position 203 of the protein (W203X). Otherwise, the authors also detected parents of two families. Each had a heterozygote of one mutation.

CONCLUSIONLate-onset methylmalonic acidemia patients had a variety of clinical manifestation, the first symptom was mainly abnormality of nervous system. One case was accompanied with hematological abnormalities. Two patients were vitamin B(12) responsive. In this study, the mutations were all detected on the fourth exon, the G482A mutation was probably associated with late-onset cases.

Adolescent ; Amino Acid Metabolism, Inborn Errors ; genetics ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; Carrier Proteins ; genetics ; Child ; Female ; Humans ; Methylmalonic Acid ; blood ; Mutation ; Pedigree ; Vitamin B 12

BACKGROUNDMethylmalonic acidemia (MMA) is a multifactorial autosomal recessive inborn error of organic acid metabolism, often presenting with neurological symptoms. As neurological disorders are often related to white matter injury, diffusion tensor imaging (DTI) is an excellent tool for assessment of white matter injury and possibly for diagnosing this disorder.

METHODSWe retrospectively analyzed DTI images of 12 patients with MMA (7 males, 5 females, age range: 7 - 12 months, mean age: 9.25 +/- 1.70 months) with negative MRI findings. And another 12 age-matched and gender-matched infants were enrolled as control subjects. Fractional anisotropy (FA) of different white matter tracts of the brain was measured in both groups.

RESULTSFor patients with negative MRI findings, compared with healthy infants, a statistically significant reduction in DTI FA value of the frontal white matter, temporal white matter, and occipital white matter was observed (P < 0.01).

CONCLUSIONSIn addition to conventional T1W and T2W MR Image, Brain DTI presents a useful, sensitive and complementary tool for the assessment of brain damage in patients with MMA.

Amino Acid Metabolism, Inborn Errors ; blood ; pathology ; Anisotropy ; Brain ; pathology ; Diffusion Magnetic Resonance Imaging ; methods ; Female ; Humans ; Infant ; Male ; Methylmalonic Acid ; blood ; Nerve Fibers, Myelinated ; pathology

We report a patient who was diagnosed as subacute combined degeneration (SCD) with elevated homocysteine and methylmalonic acid levels in the situation of a spurious elevation of the vitamin B12 concentration. A false-positive elevation of the vitamin B12 level could lead to a delayed diagnosis and cause irreversible changes in the nervous systems. We therefore suggest that the homocysteine and methylmalonic acid levels should be checked in patients with a normal or elevated vitamin B12 level for whom there is a high clinical suspicion for vitamin B12 deficiency, as a further evaluation for SCD.
Delayed Diagnosis ; Gastritis, Atrophic* ; Homocysteine ; Humans ; Methylmalonic Acid ; Nervous System ; Subacute Combined Degeneration* ; Vitamin B 12 Deficiency ; Vitamin B 12* ; Vitamins*

From June 1998 to May 2007, 9566 urine samples were collected from patients with psychomotor deficits, seizures, vomiting and unconsciousness in Peking University First Hospital. Their urine organic acids profiles were analysed using gas chromatography - mass spectrometry (GCMS), GCMS solution and Inborn Errors of Metabolism Screening System software. In all patients, blood acylcarnitines were analysed using tandem mass spectrometry. One hundred and sixty-eight patients (1.76%) with organic acidurias were detected. Among them, 116 (116/ 168, 69.0%) had methylmalonic aciduria, 63 (54.3%) of these 116 patients had methylmalonic aciduria combined with homocysteinemia. Sixteen (9.5%) of those patients detected with organic acidurias had propionic aciduria, and 15 (8.9%) had multiple carboxylase deficiency. Seven (4.2%) had glutaric aciduria type 1. After dietary treatment, medicine and rehabilitation, clinical improvements were observed in more than half of the patients. Twenty-eight of the 168 patients (16.7%) recovered and led a normal life. The method of urine organic acid analysis by gas chromatography - mass spectrometry and blood acylcarnitines analysis by tandem mass spectrometry have been established and applied successfully in China, namely Beijing, Shanghai, Wuhan and Guangzhou. The prognoses of Chinese patients with organic acidurias have also improved significantly.
Child ; Child, Preschool ; China ; Humans ; Infant ; Infant, Newborn ; Metabolic Diseases ; urine ; Methylmalonic Acid ; urine ; Multiple Acyl Coenzyme A Dehydrogenase Deficiency ; urine ; Propionic Acidemia ; urine