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Methionine Adenosyltransferase I/III Deficiency in Portugal: High Frequency of a Dominantly Inherited Form in a Small Area of Douro High Lands.

ABSTRACT: Methionine adenosyltransferase deficiency (MAT I/III deficiency) is an inborn error of metabolism resulting in isolated hypermethioninemia, and usually inherited as an autosomal recessive trait, although a dominant form has been reported in several families.During the last 6 years, approximately 520,000 newborns were screened in the Portuguese Newborn Screening Laboratory by MS/MS, and 21 cases of persistent hypermethioninemia were found. One case was confirmed to be a deficiency of cystathionine ?-synthase and 20 cases were confirmed by MAT1A gene analysis to have an elevation of methionine due to MAT I/III deficiency, which indicates an incidence for this condition of 1/26,000. Twelve of the MAT I/III deficient newborns, belonging to 11 families, were identified in the northern region of Portugal and sent to the same treatment center, where they are under follow-up. Clinical, biochemical, and genetic characteristics of individuals from these 11 families are presented. Plasma methionine and homocysteine concentrations were found to be moderately increased in all newborns, and molecular analysis revealed that they all were heterozygous for R264H mutation. Normal growth, development, and neurological examination were observed in all cases, and cerebral MRI performed in six cases revealed myelination abnormalities in one case. Plasma methionine concentration for all 12 cases was always below 300 ?M, and they are all on a normal diet for their age.

SUBMITTER: Martins E

PROVIDER: S-EPMC3565625 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Methionine Adenosyltransferase I/III Deficiency in Portugal: High Frequency of a Dominantly Inherited Form in a Small Area of Douro High Lands.

Martins E E Marcão A A Bandeira A A Fonseca H H Nogueira C C Vilarinho L L

JIMD reports 20120201

Methionine adenosyltransferase deficiency (MAT I/III deficiency) is an inborn error of metabolism resulting in isolated hypermethioninemia, and usually inherited as an autosomal recessive trait, although a dominant form has been reported in several families.During the last 6 years, approximately 520,000 newborns were screened in the Portuguese Newborn Screening Laboratory by MS/MS, and 21 cases of persistent hypermethioninemia were found. One case was confirmed to be a deficiency of cystathionin ...[more]

PMID: 23430947

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Project description:See Li and Donohue (doi:10.1093/brain/awy089) for a scientific commentary on this article.Dominantly-inherited Alzheimer's disease is widely hoped to hold the key to developing interventions for sporadic late onset Alzheimer's disease. We use emerging techniques in generative data-driven disease progression modelling to characterize dominantly-inherited Alzheimer's disease progression with unprecedented resolution, and without relying upon familial estimates of years until symptom onset. We retrospectively analysed biomarker data from the sixth data freeze of the Dominantly Inherited Alzheimer Network observational study, including measures of amyloid proteins and neurofibrillary tangles in the brain, regional brain volumes and cortical thicknesses, brain glucose hypometabolism, and cognitive performance from the Mini-Mental State Examination (all adjusted for age, years of education, sex, and head size, as appropriate). Data included 338 participants with known mutation status (211 mutation carriers in three subtypes: 163 PSEN1, 17 PSEN2, and 31 APP) and a baseline visit (age 19-66; up to four visits each, 1.1 ± 1.9 years in duration; spanning 30 years before, to 21 years after, parental age of symptom onset). We used an event-based model to estimate sequences of biomarker changes from baseline data across disease subtypes (mutation groups), and a differential equation model to estimate biomarker trajectories from longitudinal data (up to 66 mutation carriers, all subtypes combined). The two models concur that biomarker abnormality proceeds as follows: amyloid deposition in cortical then subcortical regions (∼24 ± 11 years before onset); phosphorylated tau (17 ± 8 years), tau and amyloid-β changes in cerebrospinal fluid; neurodegeneration first in the putamen and nucleus accumbens (up to 6 ± 2 years); then cognitive decline (7 ± 6 years), cerebral hypometabolism (4 ± 4 years), and further regional neurodegeneration. Our models predicted symptom onset more accurately than predictions that used familial estimates: root mean squared error of 1.35 years versus 5.54 years. The models reveal hidden detail on dominantly-inherited Alzheimer's disease progression, as well as providing data-driven systems for fine-grained patient staging and prediction of symptom onset with great potential utility in clinical trials.

Project description:BackgroundThe order and magnitude of pathologic processes in Alzheimer's disease are not well understood, partly because the disease develops over many years. Autosomal dominant Alzheimer's disease has a predictable age at onset and provides an opportunity to determine the sequence and magnitude of pathologic changes that culminate in symptomatic disease.MethodsIn this prospective, longitudinal study, we analyzed data from 128 participants who underwent baseline clinical and cognitive assessments, brain imaging, and cerebrospinal fluid (CSF) and blood tests. We used the participant's age at baseline assessment and the parent's age at the onset of symptoms of Alzheimer's disease to calculate the estimated years from expected symptom onset (age of the participant minus parent's age at symptom onset). We conducted cross-sectional analyses of baseline data in relation to estimated years from expected symptom onset in order to determine the relative order and magnitude of pathophysiological changes.ResultsConcentrations of amyloid-beta (Aβ)(42) in the CSF appeared to decline 25 years before expected symptom onset. Aβ deposition, as measured by positron-emission tomography with the use of Pittsburgh compound B, was detected 15 years before expected symptom onset. Increased concentrations of tau protein in the CSF and an increase in brain atrophy were detected 15 years before expected symptom onset. Cerebral hypometabolism and impaired episodic memory were observed 10 years before expected symptom onset. Global cognitive impairment, as measured by the Mini-Mental State Examination and the Clinical Dementia Rating scale, was detected 5 years before expected symptom onset, and patients met diagnostic criteria for dementia at an average of 3 years after expected symptom onset.ConclusionsWe found that autosomal dominant Alzheimer's disease was associated with a series of pathophysiological changes over decades in CSF biochemical markers of Alzheimer's disease, brain amyloid deposition, and brain metabolism as well as progressive cognitive impairment. Our results require confirmation with the use of longitudinal data and may not apply to patients with sporadic Alzheimer's disease. (Funded by the National Institute on Aging and others; DIAN ClinicalTrials.gov number, NCT00869817.).

Project description:BackgroundTuberculosis remains a serious world-wide health threat which requires the characterisation of novel drug targets for the development of future antimycobacterials. One of the key obstacles in the definition of new targets is the large variety of metabolic alterations that occur between cells in the active growth and chronic/dormant phases of tuberculosis. The ideal biochemical target should be active in both growth phases. Methionine adenosyltransferase, which catalyses the formation of S-adenosylmethionine from methionine and ATP, is involved in polyamine biosynthesis during active growth and is also required for the methylation and cyclopropylation of mycolipids necessary for survival in the chronic phase.ResultsThe gene encoding methionine adenosyltransferase has been cloned from Mycobacterium tuberculosis and the model organism M. smegmatis. Both enzymes retained all amino acids known to be involved in catalysing the reaction. While the M. smegmatis enzyme could be functionally expressed, the M. tuberculosis homologue was insoluble and inactive under a large variety of expression conditions. For the M. smegmatis enzyme, the Vmax for S-adenosylmethionine formation was 1.30 micromol/min/mg protein and the Km for methionine and ATP was 288 microM and 76 microM respectively. In addition, the enzyme was competitively inhibited by 8-azaguanine and azathioprine with a Ki of 4.7 mM and 3.7 mM respectively. Azathioprine inhibited the in vitro growth of M. smegmatis with a minimal inhibitory concentration (MIC) of 500 microM, while the MIC for 8-azaguanine was >1.0 mM.ConclusionThe methionine adenosyltransferase from both organisms had a primary structure very similar those previously characterised in other prokaryotic and eukaryotic organisms. The kinetic properties of the M. smegmatis enzyme were also similar to known prokaryotic methionine adenosyltransferases. Inhibition of the enzyme by 8-azaguanine and azathioprine provides a starting point for the synthesis of higher affinity purine-based inhibitors.

Dataset Information

Methionine Adenosyltransferase I/III Deficiency in Portugal: High Frequency of a Dominantly Inherited Form in a Small Area of Douro High Lands.

Publications

Methionine Adenosyltransferase I/III Deficiency in Portugal: High Frequency of a Dominantly Inherited Form in a Small Area of Douro High Lands.

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