Outcome of organic acidurias in China

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.

Prenatal diagnosis of methylmalonic aciduria by analysis of organic acids and total homocysteine in amniotic fluid / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Methylmalonic aciduria (MMA) is the most frequent disease of organic aciduria in China. Various biochemical strategies are followed for the prenatal diagnosis of MMA. However, since fetuses affected by MMA have decreased excretion of methylmalonic acid, the difficulties of prenatal biochemical diagnosis are obvious. Gas chromatography mass spectrometry (GC/MS) and tandem mass spectrometry (ESI/MS/MS) have allowed us to identify the disease in affected fetuses. The aim of this study was to determine the value of analysis of organic acids and total homocysteine in amniotic fluid in prenatal diagnosis of MMA.</p><p><b>METHODS</b>The clinical diagnoses and outcomes of nine probands with MMA and the prenatal diagnoses based on biochemical analysis of nine fetuses at risk for MMA were investigated. Amniotic fluid samples from pregnancies at risk for MMA and metabolically normal pregnancies were obtained at 16 - 24 weeks of gestation. Methylmalonic acid and methylcitric acid were measured by GC/MS, propionylcarnitine was analyzed by ESI/MS/MS, and total homocysteine was determined by fluorescence polarization immunoassay.</p><p><b>RESULTS</b>In two pregnancies, high levels of methylmalonic acid, methylcitric acid, propionylcarnitine, and total homocysteine indicated combined MMA and homocysteinemia in the fetuses. One of the mothers continued pregnancy and received cobalamin supplement as prenatal treatment, and the other terminated her pregnancy. In one pregnancy, significantly elevated levels of methylmalonic acid, methylcitric acid, and propionylcarnitine, and normal level of total homocysteine was found indicating isolated MMA in the fetus; abortion was performed on this case. In the other six pregnancies, all the levels of the above mentioned metabolites were normal suggesting that the fetuses were not affected by MMA. The diagnoses were confirmed after delivery by testing urinary organic acids and plasma total homocysteine.</p><p><b>CONCLUSIONS</b>The metabolic abnormalities of MMA occur early in gestation. The level of total homocysteine in amniotic fluid may be an additional indicator of fetal combined MMA and homocysteinemia. Determination of total homocysteine level in amniotic fluid may become a convenient and reliable method for prenatal diagnosis of the disease.</p>

Diagnosis and treatment of biotinidase deficiency-clinical study of six patients / 中华儿科杂志

<p><b>OBJECTIVE</b>To investigate the clinical and neurodevelopmental profiles of patients with biotinidase deficiency and to determine the efficacy of current therapy with respect to outcome.</p><p><b>METHODS</b>Six patients aged from 3 months to 14 years with biotinidase deficiency were confirmed by urinary organic acid analysis with gas chromatography/mass spectrometry (GC/MS) and biotinidase assay on dried blood spots. Biotin was supplemented individually (10-40 mg/d). Their clinical features, laboratory findings, and treatment regimen were reviewed.</p><p><b>RESULTS</b>All the 6 patients presented with some extent of neurological abnormalities and dermatological lesions. Cases 1 - 3 had poor feeding, vomiting, seizures, mental retardation, and lethargy onset from their early infancy, with varied degree of anemia, ketosis, acidosis, and hypoglycemia. Case 2 exhibited eczema and dermatitis from his age of 7 months. Case 4 displayed motor deficit and ataxia after 6 months of age, and generalized pustular psoriasis when he was 8 months old. Cases 5 and 6 gradually showed muscle weakness and paraplegia at the age of 7 years and 5 years, respectively. Inflammatory demyelination changes of cervical cord were evident on magnetic resonance imaging in these two patients. Case 6 had progressive optic atrophy, eczema and alopecia. Remarkable elevations of urinary lactate, pyruvate, 3-OH-propionate, methylcitrate, propionylglycine, 3-OH-isovalerate, 3-methylcrontonylglycine were confirmed in cases 1, 2, 3 and 5. Slight increase of urinary lactate, pyruvate, and 3-methylcrontonylglycine was observed in cases 4 and 6. Biotinidase activities assayed on dried blood spots from all the patients were below 0.1 pmol/(min.3 mm) Biotin supplementation for all the patients, except for case 3 who was not treated, resulted in pronounced and rapid clinical and biochemical improvement. Cases 4 and 6 had residual neurological damage comprising ataxia and motor handicap of legs, due to prolonged disease course.</p><p><b>CONCLUSIONS</b>Biotinidase deficiency intensively impairs nervous system and skin in the affected patients. Urinary organic acid analysis and blood biotinidase assay are crucial to the diagnosis. Early diagnosis and biotin supplementation can contribute significantly to the improvement of prognosis.</p>