LC-MS/MS measurements of urinary guanidinoacetic acid and creatine: Method optimization by deleting derivatization step.

BACKGROUND: Cerebral Creatine deficiency syndromes (CCDS) include three hereditary diseases affecting the metabolism of creatine (Cr): arginine glycine amidinotransferase deficiency, guanidinoacetate methyltransferase deficiency and disorders of creatine transporter. These pathologies cause a brain creatine deficiency responsible of non-specific neurological impairments with mental retardation. LC-MS/MS measurements of guanidinoacetic acid (GAA) and creatine in urine and plasma are an important screening test to identify the deficit. Analysis of this polar and basic molecules not hold on standard column requires a derivatization step to butyl-esters. To overcome this long and fastidious derivatization, an ion pairing (IP) method was chosen in this study. METHOD: IP method was validated using Comité francais d'accréditation (COFRAC) recommendations. Then, urine GAA and creatine of 15 patients with a CDS deficiency suspected were tested y LC-MS/MS using IP technique, and performances were assessed with reference laboratory method (butylation method). Moreover, references values were suggested y the study of 100 urines samples of healthy patients. RESULTS: The method developed provided a good accuracy and precision with intra and inter-day coefficients of variation (CVs) <15%. The curve was linear for the biological and pathological concentrations. The comparison with the reference method did not reveal any significant difference for analytical performances but showed a simplification of the preparation of samples. CONCLUSION: The use of IP technique that we have developed demonstrated a good correlation with the butylation method. Moreover, this new method not only allows a simplification of the technique, but also decreases in run time.

Clinical and genetic analysis of 7 Chinese patients with ß-ureidopropionase deficiency.

ß-Ureidopropionase (ßUP) deficiency is an autosomal recessive disease caused by abnormal changes in the pyrimidine-degradation pathway. This study aimed to investigate the mutation of ß-ureidopropionase gene (UPB1) gene and clinical features of 7 Chinese patients with ßUP deficiency.We reported 7 Chinese patients with ßUP deficiency who were admitted at Tianjin Children's Hospital. Urine metabolomics was detected by gas chromatography-mass spectrometry (GC-MS). Then genetic testing of UPB1 was conducted by polymerase chain reaction (PCR) method.The patients presented with developmental delay, seizures, autism, abnormal magnetic resonance imaging, and significantly elevated levels of N-carbamyl-ß-alanine and N-carbamyl-ß-aminoisobutyric acid in urine. Subsequent analysis of UPB1 mutation revealed 2 novel missense mutations (c.851G>T and c.853G>A), 3 previously reported mutations including 2 missense mutations (c.977G>A and c.91G>A) and 1 splice site mutation (c.917-1 G>A).The results suggested that the UPB1 mutation may contribute to ßUP deficiency. The c.977G>A is the most common mutation in Chinese population.

Laboratory diagnosis of creatine deficiency syndromes: a technical standard and guideline of the American College of Medical Genetics and Genomics.

Disclaimer: These ACMG Standards and Guidelines are intended as an educational resource for clinical laboratory geneticists to help them provide quality clinical laboratory genetic services. Adherence to these standards and guidelines is voluntary and does not necessarily assure a successful medical outcome. These Standards and Guidelines should not be considered inclusive of all proper procedures and tests or exclusive of others that are reasonably directed to obtaining the same results. In determining the propriety of any specific procedure or test, clinical laboratory geneticists should apply their professional judgment to the specific circumstances presented by the patient or specimen. Clinical laboratory geneticists are encouraged to document in the patient's record the rationale for the use of a particular procedure or test, whether or not it is in conformance with these Standards and Guidelines. They also are advised to take notice of the date any particular guideline was adopted, and to consider other relevant medical and scientific information that becomes available after that date. It also would be prudent to consider whether intellectual property interests may restrict the performance of certain tests and other procedures.Cerebral creatine deficiency syndromes are neurometabolic conditions characterized by intellectual disability, seizures, speech delay, and behavioral abnormalities. Several laboratory methods are available for preliminary and confirmatory diagnosis of these conditions, including measurement of creatine and related metabolites in biofluids using liquid chromatography-tandem mass spectrometry or gas chromatography-mass spectrometry, enzyme activity assays in cultured cells, and DNA sequence analysis. These guidelines are intended to standardize these procedures to help optimize the diagnosis of creatine deficiency syndromes. While biochemical methods are emphasized, considerations for confirmatory molecular testing are also discussed, along with variables that influence test results and interpretation.Genet Med 19 2, 256-263.

NMR-based urinalysis for rapid diagnosis of ß-ureidopropionase deficiency in a patient with Dravet syndrome.

BACKGROUND: Beta-ureidopropionase deficiency is a rare inborn error of metabolism (IEM) affecting pyrimidine metabolism. To-date, about 30 genetically confirmed cases had been reported. The clinical phenotypes of this condition are variable; some patients were asymptomatic while some may present with developmental delay or autistic features. In severe cases, patients may present with profound neurological deficit including hypotonia, seizures and mental retardation. Using NMR-based urinalysis, this condition can be rapidly diagnosed within 15 min. CASE: An 11-month-old Chinese boy had dual molecular diagnoses, ß-ureidopropionase deficiency and Dravet syndrome. He presented with intractable and recurrent convulsions, global developmental delay and microcephaly. Urine organic acid analysis using GC-MS and NMR-based urinalysis showed excessive amount of ß-ureidopropionic acid and ß-ureidoisobutyric acid, the two disease-specific markers for ß-ureidopropionase deficiency. Genetic analysis confirmed homozygous known disease-causing mutation UPB1 NM_016327.2: c.977G>A; NP_057411.1:p.R326Q. In addition, genetic analysis for Dravet syndrome showed the presence of heterozygous disease-causing mutation SCN1A NM_001165963.1:c.4494delC; NP_001159435.1:p.F1499Lfs*2. CONCLUSIONS: The differentiation between Dravet syndrome and ß-ureidopropionase deficiency is clinically challenging since both conditions share overlapping clinical features. The detection of urine ß-ureidoisobutyric and ß-ureidopropionic acids using NMR or GC-MS is helpful in laboratory diagnosis of ß-ureidopropionase deficiency. The disease-causing mutation, c.977G>A of ß-ureidopropionase deficiency, is highly prevalent in Chinese population (allele frequency=1.7%); ß-ureidopropionase deficiency screening test should be performed for any patients with unexplained neurological deficit, developmental delay or autism.

Urinary 8-hydroxydeoxyguanosine correlate with hallucinations rather than motor symptoms in Parkinson's disease.

BACKGROUND: Oxidative stress is causally associated with the pathogenesis of Parkinson's disease (PD). Oxygen generates a large amount of reactive oxygen species (ROS). ROS including hydroxyl radicals and H(2)O(2) react with guanine residues in DNA and produce 8-hydroxydeoxyguanosine (8-OHdG). 8-OHdG serves as a biomarker for oxidative stress in various diseases. METHOD: We investigated urinary 8-OHdG levels in 61 PD patients and 28 normal subjects to evaluate the correlation with various clinical features. We quantified disease severity using the Unified Parkinson's Disease Rating Scale for motor symptoms (UPDRS part 3), the Mini-Mental State Examination (MMSE) for mental function, and the Tottori University Hallucination Rating Scale (TUHARS) for quantifying hallucinations. RESULTS: There were significant correlations between 8-OHdG and all the examined parameters, but the partial correlation coefficients excluding contributions of all the other parameters showed that only TUHARS and UPDRS part 3 are significantly related to 8-OHdG. In particular, TUHARS correlates best with urinary 8-OHdG levels. CONCLUSION: The significant correlation between urinary 8-OHdG levels and hallucinations but not with dementia suggests that hallucinations are likely to have unique but unidentified mechanisms that lead to excessive production of 8-OHdG.

Melatonin is released in the third ventricle in humans. A study in movement disorders.

In order to determine sources and metabolism of melatonin in human cerebrospinal fluid (CSF), melatonin and 6-sulfatoxymelatonin (aMT6S) concentrations were measured in CSF sampled during neurosurgery in both lateral and third ventricles in patients displaying movement disorder (Parkinson's disease, essential tremor, dystonia or dyskinesia) and compared with their plasma levels. Previous determinations in nocturnal urine had showed that the patients displayed melatonin excretion in the normal range, compared with healthy controls matched according to age. A significant difference in melatonin concentration was observed between lateral and third ventricles, with the highest levels in the third ventricle (8.75+/-2.75 pg/ml vs. 3.20+/-0.33 pg/ml, p=0.01). CSF aMT6s levels were similar in both ventricles and of low magnitude, less than 5 pg/ml. They were not correlated with melatonin levels or influenced by the area of sampling. Melatonin levels were significantly higher in third ventricle than in the plasma, whereas there was no difference between plasma and lateral ventricle levels. These findings show that melatonin may enter directly the CSF through the pineal recess in humans. The physiological meaning of these data remains to be elucidated.

[(1)H] magnetic resonance spectroscopy of urine: diagnosis of a guanidinoacetate methyl transferase deficiency case.

For the first time, the use of urine [(1)H] magnetic resonance spectroscopy has allowed the detection of 1 case of guanidinoacetate methyl transferase in a database sample of 1500 pediatric patients with a diagnosis of central nervous system impairment of unknown origin. The urine [(1)H] magnetic resonance spectroscopy of a 9-year-old child, having severe epilepsy and nonprogressive mental and motor retardation with no apparent cause, revealed a possible guanidinoacetic acid increase. The definitive assignment of guanidinoacetic acid was checked by addition of pure substance to the urine sample and by measuring [(1)H]-[(1)H] correlation spectroscopy. Diagnosis of guanidinoacetate methyl transferase deficiency was further confirmed by liquid chromatography-mass spectrometry, brain [(1)H] magnetic resonance spectroscopy, and mutational analysis of the guanidinoacetate methyl transferase gene. The replacement therapy was promptly started and, after 1 year, the child was seizure free. We conclude that for this case, urine [(1)H] magnetic resonance spectroscopy screening was able to diagnose guanidinoacetate methyl transferase deficiency.

18Fluoro-2-deoxyglucose (18FDG) PET scan of the brain in type IV 3-methylglutaconic aciduria: clinical and MRI correlations.

The clinical, 18fluorodeoxyglucose positron emission tomography (18FDG PET) and the magnetic resonance imaging (MRI) brain scan characteristics of four patients diagnosed to have 3-methylglutaconic aciduria were reviewed retrospectively. The disease has a characteristic clinical pattern. The initial presentations were developmental delay, hypotonia, and severe failure to thrive. Later, progressive encephalopathy with rigidity and quadriparesis were observed, followed by severe dystonia and choreoathetosis. Finally, the patients became severely demented and bedridden. The 18FDG PET scans showed progressive disease, explaining the neurological status. It could be classified into three stages. Stage I: absent 18FDG uptake in the heads of the caudate, mild decreased thalamic and cerebellar metabolism. Stage II: absent uptake in the anterior half and posterior quarter of the putamina, mild-moderate decreased uptake in the cerebral cortex more prominently in the parieto-temporal lobes. Progressive decreased thalamic and cerebellar uptake. Stage III: absent uptake in the putamina and severe decreased cortical uptake consistent with brain atrophy and further decrease uptake in the cerebellum. The presence of both structural and functional changes in the brain, demonstrated by the combined use of MRI and 18FDG PET scan, with good clinical correlation, make the two techniques complementary in the imaging evaluation of 3-methylglutaconic aciduria.

3-Methyl glutaconic aciduria in Iraqi Jewish children may be misdiagnosed as cerebral palsy.

It is generally accepted that patients with cerebral palsy suffer from a static encephalopathy causing a non-progressive disorder of posture and/or movement. We describe 7 patients from 5 families who were initially diagnosed with cerebral palsy. Eventually, excessive excretion of urinary 3-methyl glutaconic acid (3-MGA) was found. The data of our 7 patients are quite similar to the clinical description of Costeff et al (1989): Jewish-Iraqi origin (7/7), consanguinity (2/7), involuntary movements (5/7), ataxia (6/7), pyramidal involvement (6/7) and optic atrophy (6/7). The cognitive functions were intact in 5/7 and 2/7 showed mild to moderate mental retardation. The mean delay in the definitive diagnosis was 9 years. Cerebral palsy-like symptoms accompanied by optic atrophy and extrapyramidal signs should call for extensive metabolic evaluation including the determination of urinary 3-MGA.

3-Methylglutaconic aciduria in the Iraqi-Jewish 'optic atrophy plus' (Costeff) syndrome.

Eleven new patients of Iraqi-Jewish origin with bilateral optic atrophy, neurological abnormalities ('optic atrophy plus' syndrome) and 3-methylglutaconic aciduria (type III) are described. Clinical abnormalities in decreasing order of frequency were bilateral optic atrophy, extrapyramidal signs, spasticity, ataxia, dysarthria and cognitive deficit. An association with age was found only for spasticity. Spasticity, extrapyramidal signs and optic atrophy frequently led to major disability, in contrast to ataxia, dysarthria and cognitive deficit. The combined excretion of 3-methylglutaconic and 3-methylglutaric acid ranged between 9 and 187 mmol/mol creatinine. The primary enzymatic defect possibly may reside in the mitochondrial respiratory chain.

Intermittently progressive dyskinetic syndrome in glutaric aciduria.

A case of glutaric aciduria, a recently discovered inborn error of tryptophan-lysine metabolism, is reported. Development was normal during the first year of life. Signs of dyskinesia and dystonia associated with developmental regression occurred twice during gastrointestinal disease. By two years of age, a dystonic syndrome with a severe motor and language disability had resulted.

Urinary monoamine metabolite excretion in disorders of movement. Effects of amantadine and levodopa.

We have studied the urinary excretion of 1,4-methylhistamine (1,4-MeHm), 5-hydroxyindole-3-acetic acid (5-HIAA) and homovanillic acid (HVA) in patients with Parkinson's disease, choreiform movements and essential tremor. The effect of amantadine on urinary excretion has been measured in each group of patients as well as the effect of levodopa in patients with Parkinson's disease. In patients with Parkinson's disease, excretion of 1,4-MeHm and HVA was significantly lower than in controls. Patients with choreiform movements had a reduced excretion of HVA but trends toward low levels of 1,4-MeHm and, in patients with Huntington's chorea, elevated excretion of 5-HIAA, were not significant. In patients with essential tremor, urinary excretion of the amine metabolities studied did nof differ significantly from controls. Administration of amantadine to patients with Parkinson's disease was not followed by increased excretion of monoamine metabolites except in those patients who were already receiving anticholinergic drugs. This increase is not significant and there was no effect in other groups of patients. These findings lend no support to the view that amantadine has a general amine-releasing action although there is limited evidence for such an effect in Parkinson's disease. In addition to the expected increase in HVA excretion, administration of levodopa to Parkinsonian patients was followed by significantly reduced excretion of 1,4-MeHm and 5-HIAA. However, if amantadine and levodopa were given together, excretion of 5-HIAA was still reduced, but that of 1,4-MeHm was normal. Levodopa may thus modify the turnover of histamine, which appears to be reduced in Parkinson's disease, and this effect may be modified by amantadine.