Biomedical subjects

L Prevost

Publications and source records attributed to L Prevost.

7 recordsLinked to original sources

PubMed2000

PAHdb: a locus-specific knowledgebase.

PAHdb is an online relational locus-specific "mutation database" (http://www.mcgill.ca/pahdb) for the human phenylalanine hydroxylase gene (symbol PAH) and its associated phenotypes (protein, metabolic, clinical). When combined with associated information (population distribution of allele, haplotype association, etc.) PAHdb functions as a knowledgebase. From the outset, and in the absence of raw data (e.g., sequence gels), PAHdb has instead been an annotated repository of information about mutations maintained by a team of curators. It is also disease-oriented, being focused on a variant phenotype (hyperphenylalaninemia (HPA) and its most important form of disease, phenylketonuria (PKU)) resulting from primary dysfunction of the PAH enzyme (EC 1.14.16.1); it is "patient friendly" in that it contains information for those personally involved with HPA/PKU (MIM# 261600). PAHdb also serves its community through direct interaction.

Alleles↗

PubMed1998

PAH Mutation Analysis Consortium Database: 1997. Prototype for relational locus-specific mutation databases.

PAHdb (http://www.mcgill.ca/pahdb ) is a curated relational database (Fig. 1) of nucleotide variation in the human PAH cDNA (GenBank U49897). Among 328 different mutations by state (Fig. 2) the majority are rare mutations causing hyperphenylalaninemia (HPA) (OMIM 261600), the remainder are polymorphic variants without apparent effect on phenotype. PAHdb modules contain mutations, polymorphic haplotypes, genotype-phenotype correlations, expression analysis, sources of information and the reference sequence; the database also contains pages of clinical information and data on three ENU mouse orthologues of human HPA. Only six different mutations account for 60% of human HPA chromosomes worldwide, mutations stratify by population and geographic region, and the Oriental and Caucasian mutation sets are different (Fig. 3). PAHdb provides curated electronic publication and one third of its incoming reports are direct submissions. Each different mutation receives a systematic (nucleotide) name and a unique identifier (UID). Data are accessed both by a Newsletter and a search engine on the website; integrity of the database is ensured by keeping the curated template offline. There have been >6500 online interrogations of the website.

Animals↗

PubMed1997

The PAH mutation analysis consortium database: update 1996.

A website (http://www.mcgill.ca/pahdb ) is maintained by the curators for a Consortium (88 investigators, 28 countries) and all other users; it serves a relational database for human locus-specific genetic variation in a defined DNA sequence (GenBank U49897); (100 kb on human chromosome 12q24.1, gene symbol PAH). The intragenic nucleotide variation is both rare (Q< 0.01), extensive (>320 different mutations) and phenotype modifying, causing hyperphenylalaninemia by impairing phenylalanine hydroxylase function (see OMIM 261600), as well as polymorphic and neutral, the latter providing informative locus-specific haplotypes (>1200 different mutation/haplotype associations). The PAH database contains both offline core components (mutations, population associations and data source information) and several accessory online components: (i) relative frequencies of mutations by populations/regions (expanding file); (ii) data on genotype- phenotype correlations both in vitro and in vivo (new file); (iii) polymorphic haplotype structures (new file); (iv) intron sequence data (new file for design of primers); (v) description of mouse homologues (new file for mutations and phenotypes); (vi) the predicted PAH gene mutability profile (improved graphic); (vii) a clinical field for patient use (new interface with database). The website home page has been revised and a counter is recording >15 visits per day. Linkages to other mutation databases and an alliance of mutation database curators (new) are expanding. The primary 'electronic publication' reports now vastly exceed print reports. PAHdb serves as a prototype for obtaining, storing and distributing records of human genetic variation.

Animals↗

PubMed1996

PAH Mutation Analysis Consortium Database: a database for disease-producing and other allelic variation at the human PAH locus.

The PAH Mutation Analysis Consortium (81 investigators, 26 countries) is engaged in mutation detection at the human PAH locus. Ascertainment of probands occurs largely through newborn screening for hyperphenylalaninemia. A relational database records allelic variation (disease-producing and polymorphic) at the locus. Information is distributed by Newsletter, diskette (WINPAHDB software stand-alone executable on IBM compatible hardware), and at a 'real' site on the Worldwide Web (http://www.mcgill.ca/pahdb). The database presently records (Sept. 27, 1995) 248 alleles in 798 different associations (with polymorphic haplotype, geographic region and population) along with additional information. The database, as a record of human genetic diversity, at a particular locus, contributes to the study of human evolution and demic expansion; it also has medical relevance.

Alleles↗

PubMed1996

The phenylalanine hydroxylase locus: a marker for the history of phenylketonuria and human genetic diversity. PAH Mutation Analysis Consortium.

Disease-producing allelic variation describes one aspect of human genetic diversity. Phenylketonuria, the major type of hyperphenylalaninaemia and formerly a functional genetic lethal, has a 2% carrier frequency in temperate-zone populations. Newborn screening for hyperphenylalaninaemia (incidence of 1 in 10000) has made it one of the most widely ascertained human Mendelian traits; 99% of hyperphenylalaninaemia mutations map to the PAH (phenylalanine hydroxylase) gene on 12q24.1, and most cause phenylketonuria. The gene is well characterized. Analysis of 3986 mutant chromosomes by 81 investigators in 26 countries has identified 243 different mutations in 788 different associations (with polymorphic intragenic haplotypes [seven diallelic sites, one short tandem repeat, one variable number of tandem repeats], populations and regions). These data are compiled on a database accessible on the World-Wide Web or as a stand-alone software package. A few phenylketonuria alleles occur at high relative frequencies in particular populations on one or only a few haplotypes, suggesting positive selection in the past. Additional mechanisms (founder effect, drift and recurrent mutation) can explain frequencies and distributions of particular alleles. Allele stratification in Europeans and Orientals implies that mechanism(s) accounting for distribution and high frequencies of PAH alleles were acting before and during demic expansion in Europe and after the European and Oriental radiations.

Genetic Markers↗

PubMed1988

Somatosensory receptive fields of fibres in the rostral corpus callosum of the cat.

The corpus callosum is the principal neocortical commissure which transmits lateralized information between the hemispheres. The aim of the present experiment was to study the receptive field (RF) properties of somatosensory callosal fibres in the cat. The callosum was approached under direct visual control and axonic responses were recorded under N2O anaesthesia using tungsten microelectrodes or, mostly, glass micropipettes. RFs representing all the sensory submodalities tested (light touch, medium and deep pressure, joint movement and light pinches) were found to be present in the axons which travelled through the callosum. Rapidly adapting units were more common than slowly adapting ones. The axial and para-axial portions of the body accounted for about three-fifths of all RFs, followed by the head (about one-fifth), with the rest responding to stimulation of the extremities. The medial borders of most of the unilateral RFs situated on the trunk and, to a lesser degree, the head, extended to the mid-line. The results are interpreted in terms of the roles of the corpus callosum in mid-line fusion and interhemispheric transfer.

Afferent Pathways↗

PubMed1987

Receptive field properties of somatosensory callosal fibres in the monkey.

The corpus callosum is the principal neocortical commissure which transmits lateralized information between the hemispheres. The aim of the present experiment was to study the receptive field properties of somatosensory callosal fibres in rhesus macaque monkeys. The callosum was approached under direct visual control and axonic responses were recorded using tungsten microelectrodes. All sensory submodalities which could be examined with the available instruments were found (light touch, medium and deep pressure, joint movement and light pinches). Most fibres had receptive fields concerned with the trunk, followed by the head, with only a few responding to stimulation of the extremities. The medial borders of the unilateral receptive fields situated on the trunk and the head extended to the midline. The results are interpreted in terms of the roles of the corpus callosum in midline fusion and interhemispheric transfer.

Animals↗