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A novel HLA-A∗30 null allele with disulfide bridge disruption in the alpha 2 domain
Abstracts
S157
6.03 #221
DESCRIPTION OF A NEW DRB1*11 ALLELE FOUND IN THE FAMILY OF A BONE MARROW TRANSPLANTATION CANDIDATE M. Guadalupe Ercilla,1 Virginia Mas,1 M. Teresa Arias,1 Virginia Fabregat,1 Benet Nomdedeu,2 Carles Serra,1 Jordi Vives,1 Jaime Martorell.1 1Servicio de Immunologı´a. Institut Clinic d’Infeccions i Immunologia.(ICII), Hospital Clinic. Institut d’Investigacions Biome`diques August Pi i Sunyer (IDIBAPS), Barcelona, Spain; 2Institut Clinic de Malaties HematoOncolo`giques (ICMHO), Hospital Clinic, Barcelona, Spain Matching for human leukocyte antigens (HLA) is a critical step in the selection procedure of bone marrow donors with regard to GVHD prevention or rejection after bone marrow transplantation. The human major histocompatibility complex MHC, particularly the class II region, is characterized by an extremely high polymorphism. We describe the identification of a novel DRB1* allele, found in a three generation family. The identification by SBT of a new HLA-DRB1*11 allele was observed in a Spanish Caucasoid family during a research for a histocompatible bone marrow donor. The novel allele differs from DRB1*1123 in one nucleotide at position 199 (A replacing T) in exon 2, leading to one aminoacid change from Phenylalanine to Isoleucine (Ile) at codon 67. Codon 67 codifying for Ile is very common among DRB1*11 alleles, being the unique diference from DRB1*1123 in exon 2. Aminoacid residue polymorphisms at codon 67, located at the a-helix in the betachain, are involved in peptide accommodation in pocket 7. The new DRB1 allele is carried on the haplotype HL A*6801; B*0702; Cw*0702; DRB1*11New; DRB3*0202; DQB1*0301. The father was identical to the propositus by low resolution testing (two digits) but differs from locus B (B*4403 by B*4402) and locus C (Cw*1502 by Cw*05AC). We discuss the criteria of selecting a non related bone marrow donor with a minor mismatch on BRB1 allele or the related father having a minor B locus mismatch and a C locus mismatch. The allele, available from the EMBL Nucleotide Sequence Database under accession number AY 307897, has been submitted to obtain an official allele assignment from the WHO Nomenclature Committee.
6.03 #222
A NOVEL HLA-A*30 NULL ALLELE WITH DISULFIDE BRIDGE DISRUPTION IN THE ALPHA 2 DOMAIN Kaimo Hirv, Klaus Schwarz. Transplantation Immunology, Institute for Clinical Transfusion Medicine and Immunogenetics Ulm gGmbH, Ulm, Germany A male Caucasian CML patient and his unrelated bone marrow donor were considered to be HLA-matched on the basis of the serological HLA class I and DNA-based class II typing. Retrospective DNA-based class I typing of the patient was inconsistent with the serologic results and lead to the identification of a novel HLAA*30 null allele (GenBank accession number AY323229). The patient was typed serologically as A2 homozygot. DNA-based typing (PCR-SSOP) detected an additional A*30 allele without unexpected reaction patterns. Sequence based typing identified a novel HLAA*30 null allele. The novel allele was found on a haplotype with B*1402, Cw*0802, DRB1*0102, DQB1*0501 according to the segregation analysis of the family. The nucleotide sequence of the A*30 null variant is identical to A*3001 except for a G563C substitution in exon 3 resulting in the amino acid difference C164S. In the absence of the C164 a disulfide bridge within the alpha 2 domain can not be formed. It is believed to affect the stable binding of beta-2 microglobulin and peptide to the MHC class I heavy chain which in turn end up in the loss of the MHC class I cell surface expression. The patient carrying the HLA-A*30 null allele was in complete remission on day ⫹1141 post-transplant. Even though, there was a major mismatch in this transplantation setting based on HLA class I DNA typing, the selection of a donor with a functional major mismatch in HVG direction was avoided with serological typing. Probably all of the commercially available SSP/SSO techniques will fail to detect this novel HLAA*30 null allele because of the mutation in the highly conserved region. Maintenance of serological typing in addition to DNA-based techniques is the simplest way to detect null alleles until the DNA-based methods are refined.
S157
6.03 #221
DESCRIPTION OF A NEW DRB1*11 ALLELE FOUND IN THE FAMILY OF A BONE MARROW TRANSPLANTATION CANDIDATE M. Guadalupe Ercilla,1 Virginia Mas,1 M. Teresa Arias,1 Virginia Fabregat,1 Benet Nomdedeu,2 Carles Serra,1 Jordi Vives,1 Jaime Martorell.1 1Servicio de Immunologı´a. Institut Clinic d’Infeccions i Immunologia.(ICII), Hospital Clinic. Institut d’Investigacions Biome`diques August Pi i Sunyer (IDIBAPS), Barcelona, Spain; 2Institut Clinic de Malaties HematoOncolo`giques (ICMHO), Hospital Clinic, Barcelona, Spain Matching for human leukocyte antigens (HLA) is a critical step in the selection procedure of bone marrow donors with regard to GVHD prevention or rejection after bone marrow transplantation. The human major histocompatibility complex MHC, particularly the class II region, is characterized by an extremely high polymorphism. We describe the identification of a novel DRB1* allele, found in a three generation family. The identification by SBT of a new HLA-DRB1*11 allele was observed in a Spanish Caucasoid family during a research for a histocompatible bone marrow donor. The novel allele differs from DRB1*1123 in one nucleotide at position 199 (A replacing T) in exon 2, leading to one aminoacid change from Phenylalanine to Isoleucine (Ile) at codon 67. Codon 67 codifying for Ile is very common among DRB1*11 alleles, being the unique diference from DRB1*1123 in exon 2. Aminoacid residue polymorphisms at codon 67, located at the a-helix in the betachain, are involved in peptide accommodation in pocket 7. The new DRB1 allele is carried on the haplotype HL A*6801; B*0702; Cw*0702; DRB1*11New; DRB3*0202; DQB1*0301. The father was identical to the propositus by low resolution testing (two digits) but differs from locus B (B*4403 by B*4402) and locus C (Cw*1502 by Cw*05AC). We discuss the criteria of selecting a non related bone marrow donor with a minor mismatch on BRB1 allele or the related father having a minor B locus mismatch and a C locus mismatch. The allele, available from the EMBL Nucleotide Sequence Database under accession number AY 307897, has been submitted to obtain an official allele assignment from the WHO Nomenclature Committee.
6.03 #222
A NOVEL HLA-A*30 NULL ALLELE WITH DISULFIDE BRIDGE DISRUPTION IN THE ALPHA 2 DOMAIN Kaimo Hirv, Klaus Schwarz. Transplantation Immunology, Institute for Clinical Transfusion Medicine and Immunogenetics Ulm gGmbH, Ulm, Germany A male Caucasian CML patient and his unrelated bone marrow donor were considered to be HLA-matched on the basis of the serological HLA class I and DNA-based class II typing. Retrospective DNA-based class I typing of the patient was inconsistent with the serologic results and lead to the identification of a novel HLAA*30 null allele (GenBank accession number AY323229). The patient was typed serologically as A2 homozygot. DNA-based typing (PCR-SSOP) detected an additional A*30 allele without unexpected reaction patterns. Sequence based typing identified a novel HLAA*30 null allele. The novel allele was found on a haplotype with B*1402, Cw*0802, DRB1*0102, DQB1*0501 according to the segregation analysis of the family. The nucleotide sequence of the A*30 null variant is identical to A*3001 except for a G563C substitution in exon 3 resulting in the amino acid difference C164S. In the absence of the C164 a disulfide bridge within the alpha 2 domain can not be formed. It is believed to affect the stable binding of beta-2 microglobulin and peptide to the MHC class I heavy chain which in turn end up in the loss of the MHC class I cell surface expression. The patient carrying the HLA-A*30 null allele was in complete remission on day ⫹1141 post-transplant. Even though, there was a major mismatch in this transplantation setting based on HLA class I DNA typing, the selection of a donor with a functional major mismatch in HVG direction was avoided with serological typing. Probably all of the commercially available SSP/SSO techniques will fail to detect this novel HLAA*30 null allele because of the mutation in the highly conserved region. Maintenance of serological typing in addition to DNA-based techniques is the simplest way to detect null alleles until the DNA-based methods are refined.