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Steven G E Marsh

Publications and source records attributed to Steven G E Marsh.

At least 19 recordsLinked to original sources
PubMed2026

HLA Diversity of Over 500,000 Individuals on the DATRI Register Across 18 Regions in India.

Registries of unrelated stem cell donors can use HLA haplotype frequencies to aid in registry management. DATRI is India's largest registry with over 550,000 donors, with donors in 35 of India's 36 states and union territories. A geographical based analysis on HLA haplotype frequencies has not previously been carried out with an Indian dataset of this size. To balance granularity and accuracy in estimating 5-locus haplotype frequencies for HLA-A, -C, -B, -DRB1 and -DQB1, we grouped donors into 18 regions with a minimum population size of 2000 donors. We identified the most frequent haplotype as A*33:03-ARD~C*07:01-ARD~B*44:03-ARD~DRB1*07:01-ARD~DQB1*02:01-ARD in Odisha (6.09%), which was also the most frequent haplotype in nine other regions. Assigning the most likely diplotypes to donors, there were a total of 57,959 haplotypes and just 202 (0.3%) of those were present in all 18 regions. HLA-B had the greatest number of alleles across the whole dataset (559) and HLA-DQB1 the least (167). However, HLA-C displayed the most inter-region diversity with only 6.7% of HLA-C alleles present in all regions (average 9.5%). We clustered the regions, using Nei's standard genetic distance, and these correlated with geography; however, three regions (North India, Kerala, and the Gujarat area) did not fit into any cluster. These regions each had one or more distinctive haplotypes that were very frequent (≥ 0.5%) in that region alone. Additionally, the Gujarat area had the lowest diversity metrics. These data can be used to inform the management of registries and contribute to our understanding of HLA diversity globally.

Humans↗
PubMed2005

IPD--the Immuno Polymorphism Database.

The Immuno Polymorphism Database (IPD) (http://www.ebi.ac.uk/ipd/) is a set of specialist databases related to the study of polymorphic genes in the immune system. IPD currently consists of four databases: IPD-KIR, contains the allelic sequences of Killer-cell Immunoglobulin-like Receptors; IPD-MHC, a database of sequences of the Major Histocompatibility Complex of different species; IPD-HPA, alloantigens expressed only on platelets; and IPD-ESTAB, which provides access to the European Searchable Tumour Cell-Line Database, a cell bank of immunologically characterized melanoma cell lines. The IPD project works with specialist groups or nomenclature committees who provide and curate individual sections before they are submitted to IPD for online publication. The IPD project stores all the data in a set of related databases. Those sections with similar data, such as IPD-KIR and IPD-MHC share the same database structure. The sharing of a common database structure makes it easier to implement common tools for data submission and retrieval. The data are currently available online from the website and ftp directory; files will also be made available in different formats to download from the website and ftp server. The data will also be included in SRS, BLAST and FASTA search engines at the European Bioinformatics Institute.

Animals↗
PubMed2005

HLA dictionary 2004: summary of HLA-A, -B, -C, -DRB1/3/4/5, -DQB1 alleles and their association with serologically defined HLA-A, -B, -C, -DR, and -DQ antigens.

This report presents serologic equivalents of human leukocyte antigen (HLA)-A, -B, -C, -DRB1, -DRB3, -DRB4, -DRB5, and -DQB1 alleles. The dictionary is an update of the one published in 2001. The data summarize equivalents obtained by the World Health Organization (WHO) Nomenclature Committee for Factors of the HLA System, the International Cell Exchange (UCLA), the National Marrow Donor Program, recent publications, and individual laboratories. This latest update of the dictionary is enhanced by the inclusion of results from studies performed during the 13th International Histocompatibility Workshop and from neural network analyses. A summary of the data as recommended serologic equivalents is presented as expert assigned types. The tables include remarks for alleles, which are or may be expressed as antigens with serologic reaction patterns that differ from the well-established HLA specificities. The equivalents provided will be useful in guiding searches for unrelated hematopoietic stem cell donors in which patients and/or potential donors are typed by either serology or DNA-based methods. The serological-DNA equivalent dictionary will also aid in typing and matching procedures for organ transplant programs whose waiting lists of potential donors and recipients are comprised of mixtures of serologic and DNA-based typings. The tables with HLA equivalents and a questionnaire for submission of serologic reaction patterns for poorly identified allelic products will be made available through the World Marrow Donor Association Web page (www.worldmarrow.org).

Alleles↗
PubMed2004

High frequency of homozygosity of the HLA region in melanoma cell lines reveals a pattern compatible with extensive loss of heterozygosity.

Malignant transformation of cells is frequently associated with abnormalities in human leukocyte antigen (HLA) expression. MHC class I loss or down-regulation in cancer cells is a major immune escape route used by a large variety of human tumours to evade antitumour immune responses mediated by cytotoxic T lymphocytes. The goal of our study was to explore HLA genotyping and phenotyping in a variety of melanoma tumour cell lines. A total of 91 melanoma cell lines were characterised for HLA class I and II genotype. In addition, 61 out of the 91 cell lines were also analysed for HLA class I and II cell surface molecule expression by flow cytometry. Unexpectedly, we found that 19.7% of the melanoma cell lines were homozygous for HLA class I genotypes, sometimes associated with HLA class II homozygosity (8.79%) and sometimes not (10.98%). The frequency of homozygosity was significantly higher compared with the control groups (1.6%). To identify the reasons underlying the high frequency of HLA homozygosity we searched for genomic deletions using eight pairs of highly polymorphic microsatellite markers covering the entire extended HLA complex on the short arm of chromosome 6. Our results were compatible with hemizygous deletions and suggest that loss of heterozygosity on chromosome arm 6p is a common feature in melanoma cell lines. In fact, although autologous normal DNA from the patients was not available and could not be tested, the retention in some cases of heterozygosity for a number of microsatellite markers would indicate a hemizygous deletion. In the rest of the cases, markers at 6p and 6q showed a single allele pattern indicating the probable loss of part or the whole of chromosome 6. These results led us to conclude that loss of heterozygosity in chromosome 6 is nonrandom and is possibly an immunologically relevant event in human malignant melanoma. Other well-established altered HLA class I phenotypes were also detected by flow cytometry that correspond to HLA class I total loss and HLA-ABC and/or specific HLA-B locus down-regulation.

Chromosomes, Human, Pair 6↗