China
Africa
Explore chapters and articles related to this topic
Familial Chordoma
Published in Dongyou Liu, Handbook of Tumor Syndromes, 2020
Alexandra Suttman, Sydney T. Grob, Jean M. Mulcahy Levy
TBXT (previously identified as T brachyury transcription factor) is the 2018 updated nomenclature endorsed by the HUGO Gene Nomenclature Committee for the gene that encodes a tissue-specific transcription factor that is expressed in the nucleus of notochord cells [9]. It is essential for proper development and maintenance of the notochord [10]. Its expression in chordomas mimics expression in the embryonic notochord [2]. A recent study of 104 cases of sporadic chordoma found somatic duplication of TBXT in up to 27% of cases [11].
Pili and Hosts
Published in Paul Pumpens, Single-Stranded RNA Phages, 2020
In order to prevent confusion with the tra gene nomenclature, an explanation from an authoritative review (Willetts and Skurray 1980) is included here, according to which the 19 known transfer genes were conveniently divided into 4 groups. The first group included the above-mentioned genes traA, L, E, K, D, V; W. C, U, F, H, G, which were directly required for pilus formation and hence for recipient cell recognition and mating pair formation, as well as for infection by the F-specific phages. The second group contained traN and traG, required for stabilization of mating pairs, and the third included traM, Y. G, D, L Z, which were concerned with conjugal DNA metabolism. Mutants in the genes belonging to these two groups still synthesized the pilus and consequently retained sensitivity to the F-specific phages, except that traD mutants, though sensitive to filamentous DNA phages and to the phage Qβ, were resistant to the group I phages f2, R17, and MS2 because of inability of the phage RNA to penetrate the cell envelope (Achtman et al. 1971; Paranchych 1975). The sole gene in the fourth group, traJ, controlled expression of most if not all of the other transfer genes (Finnegan and Willetts 1973).
Genetics of immunoglobulins: Ontogenic, biological, and clinical implications
Published in Gabriel Virella, Medical Immunology, 2019
The four C-region genes on human chromosome 14 that encode the four IgG subclasses are very tightly linked. Because of this tight linkage, GM allotypes of various subclasses are transmitted as a group called haplotype. Also, because of almost absolute linkage disequilibrium between the alleles of various IgG C-region genes, certain allotypes of one subclass are always associated with certain others of another subclass. For example, the IgG1 gene controls G1M 3, whereas the IgG3 gene controls G3M 5 and G3M 21. We should expect to find G1M 3 associated with G3M 5 as often as with G3M 21; in fact, in Caucasians, a haplotype carrying G1M 3 is almost always associated with G3M 5 and not with G3M 21. Every major ethnic group has a distinct array of several GM haplotypes. GM* 3 23 5,10,11,13,14,26 and GM* 1,17 5,10,11,13,14,26 are examples of common Caucasian and Negroid haplotypes, respectively. In accordance with the international system for human gene nomenclature, haplotypes and phenotypes are written by grouping together the markers that belong to each subclass, by the numerical order of the marker and of the subclass; markers belonging to different subclasses are separated by a space, while allotypes within a subclass are separated by commas. An asterisk is used to distinguish alleles and haplotypes from phenotypes.
Systematic review of human gut resistome studies revealed variable definitions and approaches
Published in Gut Microbes, 2020
Jeffery Ho, Yun Kit Yeoh, Nilakshi Barua, Zigui Chen, Grace Lui, Sunny H Wong, Xiao Yang, Martin CW Chan, Paul KS Chan, Peter M Hawkey, Margaret Ip
The use of metagenomic shotgun sequencing circumvents the problem of non-culturable gut commensals.52–54 The results are often limited by the bioinformatics pipelines and ARG database(s) selected for analyses. Recently, the National Center for Biotechnology Information (NCBI) produced a high-quality, curated, AMR gene reference database consisting of up-to-date protein and gene nomenclature. A comparison of the susceptibilities of three common Gram-negative foodborne pathogens against the database gave high consistent predictions of 98.4%. This database is designated as AMRFinder with more than 390,000 entries, which is one of the most comprehensive databases.50 However, the small size of the contigs which are assembled renders the characterization of the resistance-gene harboring transposons or other mobile elements difficult.21 This can be overcome by constructing and screening of fosmid libraries using longer DNA fragments isolated from pulsed-field gel electrophoresis assuming that the gene encodes the same phenotype in both the heterologous host and the native bacterium.8
Prader-Willi syndrome and Angelman syndrome: Visualisation of the molecular pathways for two chromosomal disorders
Published in The World Journal of Biological Psychiatry, 2019
Friederike Ehrhart, Kelly J. M. Janssen, Susan L. Coort, Chris T. Evelo, Leopold M. G. Curfs
SNURF-SNRPN is a bicistronic gene, encoding two different proteins (Driscoll et al. 1993; Duker et al. 2010). One of those is the small nucleolar ribonucleoprotein polypeptide N (SNRPN) upstream reading frame, or SNURF. The function of SNURF is currently unclear, hence the gap annotation in the PWS pathway (Figure 5). SNRPN encodes a protein called SmN, but this is presented according to HGNC (Human Gene Nomenclature) as SNRPN in the PWS pathway. SNRPN is involved in the formation of the spliceosomal A complex, which is in turn an important component in the major splicing pathway of mRNA processing (mRNA_splicing_pathway 2017). Looking at the expression pattern, one could argue that SNRPN has something to do with the development of the brain or the remaining nervous system (Petryszak et al. 2016; SNRPN_Expression_pattern 2017). However, there is no evidence of how SNRPN would play a role in any pathway concerning this process. All in all, despite the fact that SNRPN was long thought to be the most important gene causing the clinical appearance of PWS (as it is part of the local imprinting centre and methylation analysis of its promoter correctly reveals PWS with high accurateness) (Glenn et al. 1996), very little information on its mechanism of action is available.
Important pharmacogenomic aspects in the management of HIV/AIDS
Published in South African Family Practice, 2019
A Marais, E Osuch, V Steenkamp, L Ledwaba
Approximately 80% of all drugs are metabolized by the hepatic cytochrome P450 enzyme system, of which the phase 1 metabolism iso-forms CYP1A2 (8.9%), CYP2C9 (12.8%), CYP2C19 (6.8%), CYP2D6 (20%), and CYP3A4/CYP3A5 (30.2%) are the most important.6 Each CYP450 enzyme is encoded for by a specific gene, which in turn is determined by inherited alleles – one from each parent. These alleles contribute to the phenotype (observable characteristics) of the individual, and may either be dominant or recessive.7 When heterozygous alleles are present, the dominant allele will determine the phenotype. Alleles occurring most commonly in the general population are known as “wild type” (or normal), whereas “variant” (or mutation) recessive alleles will only determine the phenotype if a homozygous combination is present. Sequence variations (or Single Nucleotide Polymorphisms/variations – SNPs or SNVs) may occur when a variant allele replaces one or both wild-type alleles. Every individual SNV is allocated a unique reference SNP ID number (rs#) by the HUGO Gene Nomenclature Committee (HGNC) – established by the US National Human Genome Research institute and the Wellcome Trust, to ensure unambiguous reference to genes in scientific communications.8 Variant alleles usually encode an enzyme or protein that has reduced (or no) activity, resulting in phenotypical changes which may have an altered effect on drug metabolism or response.9