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PubMed1995

Impact of racial genetic polymorphism on the probability of finding an HLA-matched donor.

As successful organ or marrow transplantation correlates with the degree of HLA-compatibility between patient and donor, registries have been developed to facilitate matching. However, racial minority groups have a lower chance of finding a match. We evaluate the impact of the biology of racial genetic polymorphism upon the probability of finding an HLA match for patients of different racial groups. The National Marrow Donor Program has compiled the HLA types of 20,449 patients and 1,625,159 potential volunteer donors. These HLA types were used to estimate the probability of finding an HLA-matched donor for patients of different racial groups. We estimated the HLA haplotype frequencies for different races, and then determined the probability of finding matched donors, given several hypothetical registry sizes. We confirmed that patients of minority races searching the current National Marrow Donor Program registry have low probabilities of finding matches. This was only partly due to the smaller number of donors from these racial minorities, as the observation persisted even when hypothetical donor registry sizes were the same for all racial groups. We demonstrate that African-Americans are more polymorphic with respect to HLA, and are hence less likely to find donors at any given registry size. An increase in the recruitment of minority racial groups for organ and marrow donors will only partially alleviate the problem of equal access to HLA matches for patients belonging to racial minority groups. It will therefore be important to attempt to improve methods for transplantation using HLA-mismatched donors.

HLA Antigens↗

PubMed2001

Assessment of barriers to bone marrow donation by unrelated African-American potential donors.

African Americans have a lower registration rate for becoming potential bone marrow and stem cell donors. The same attitudes and behaviors are exhibited in regard to solid organ and blood donations, causing a serious under-representation of the African-American population in the donor pool. In our efforts to increase donor availability for African Americans through a project funded by the Medical University of South Carolina, we used a survey to determine the reasons African Americans do not participate as donors for bone marrow. We surveyed 589 African Americans, a great majority of whom were women. Our survey identified major barriers to donation to be the lack of awareness that transplantation can save lives, the cost of donation, and the lack of opportunities to donate. The most effective interventions in increasing donation have been to provide both educational programs preceding marrow drives and the opportunity to donate. Through these efforts, the number of potential African-American donors has increased from 768 (accrued over a period of 12 years) to 1977 in less than 2 years. We conclude that a minority recruitment program targeting African-American volunteers for the National Marrow Donor Program (NMDP) should include an education component addressing the most common barriers before drives.

Adolescent↗

PubMed2002

Unrelated donor bone marrow transplantation for children with juvenile myelomonocytic leukaemia.

Children with juvenile myelomonocytic leukaemia (JMML) have a poor outcome, with survival in a minority of patients. The major limitation on success of sibling donor bone marrow transplantation for JMML has been reported to be relapse. A total of 46 children with a diagnosis of JMML underwent unrelated donor marrow (URD) transplantation facilitated by the National Marrow Donor Program. Forty-three of 46 patients had neutrophil engraftment at a median of 20 d post transplant, with platelet recovery in 28 of 40 evaluable patients at a median of 34.5 d. Thirty-two of 44 evaluable patients developed acute graft-versus-host-disease (GVHD) (Grades 2-4) and chronic GVHD developed in 14 of 35 evaluable patients. At a median follow-up of 2.0 years, probabilities of survival and disease-free survival were 42% and 24% respectively. The probability of relapse was 58% at 2 years and represents the major cause of treatment failure. Multivariate analysis revealed that chronic GVHD was associated with reduced relapse [risk ratio 0.20 (95% CI 0.04-1.02, P=0.05)] improved survival [risk ratio 0.13 (95% CI 0.03-0.68, P=0.02)] and event-free survival [risk ratio 0.23 (95% CI 0.06-0.94, P=0.04)]. This study demonstrates that relapse is the major cause of treatment failure in patients with JMML undergoing URD transplantation. With lower relapse observed in patients with chronic GVHD, new treatment strategies that focus on enhancing the graft-versus-leukaemia effect may improve survival.

Acute Disease↗

PubMedDate not supplied

When altruism fails: reactions of unrelated bone marrow donors when the recipient dies.

This article examines the responses of bone marrow donors to the death of the unrelated person to whom they donated. Data analyzed were 330 questionnaires and fifty in-depth interviews collected from donors in the National Marrow Donor Program at one year post-donation. Death of the recipient produced feelings of guilt and responsibility in the donors in only a few cases (2% of donors from questionnaire data and 2 of the 23 donors interviewed). Grief occurred often (22 of 23 donors interviewed) and was often surprisingly intense, given the fact that the recipient was a stranger. Intensity of grief varied depending on the perceived relationship with the recipient. Our data indicate that limiting contact and/or information about the recipient to the donor would be unlikely to result in more positive psychosocial outcomes. However, several strategies which might be useful in relieving donor guilt and/or grief are suggested.

Bone Marrow Transplantation↗

PubMed2005

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

This report presents serologic equivalents of human leucocyte 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 Nomenclature Committee for factors of the HLA System, the International Cell Exchange, 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 comprise 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 WMDA web page: www.worldmarrow.org. and in the near future also in a searchable form on the IMGT/HLA database.

Dictionaries, Medical as Topic↗

PubMed2000

A survey of allogeneic bone marrow transplant programs in the United States regarding cytomegalovirus prophylaxis and pre-emptive therapy.

Despite an extensive literature, no consensus has emerged regarding the optimal preventive strategy for CMV in allogeneic bone marrow transplantation (BMT). No survey of CMV prevention in BMT centers in the United States has yet been published. A questionnaire was sent to all allogeneic BMT programs in the United States, as listed in the November 1998 National Marrow Donor Program (NMDP) address roster. Questions included whether universal prophylaxis, pre-emptive therapy, or some other strategy was used for CMV prevention, and which CMV diagnostic tests were utilized. Eighty-one of 96 programs (86%) responded to the survey. Of these, 46 (56%) utilize a pre-emptive ganciclovir strategy, whereas 17 (21%) utilize universal prophylaxis, and 15 (19%) utilize a hybrid strategy based on risk stratification. The most commonly utilized CMV diagnostic tests are CMV-DNA by PCR (55 centers), shell vial centrifugation culture (52), tissue culture (42), pp65 antigenemia assay (38), and CMV-DNA by Digene hybrid capture (14). Of these, the CMV-DNA by PCR, pp65 antigenemia assay, and shell vial culture are the most frequently utilized as triggers for pre-emptive therapy. Quantitative assays are common (PCR 42%, Digene 64%). We conclude that centers currently performing allogeneic BMT in the United States employ a variety of strategies for CMV prevention, and differ in their diagnostic tests of choice for CMV monitoring. These results emphasize the need for large-scale studies to identify optimal diagnostic and management protocols. Bone Marrow Transplantation (2000) 26, 763-767.

Bone Marrow Transplantation↗

PubMed1996

Computer program to predict likelihood of finding and HLA-matched donor: methodology, validation, and application.

Approximately 65% of the patients requiring bone marrow transplantation do not have an HLA-A, -B, -DR identical sibling and therefore need to find a phenotypically matched unrelated donor. As of June 30, 1996, the National Marrow Donor Program maintains a registry of 2.31 million volunteer donors, 35% of whom are fully typed for HLA-A, -B, -DR loci. Because a majority of the donors has not been DR typed, a patient who does not find a complete match at the time of the preliminary search may elect to prospectively DR type A, B matched and A, B one-antigen mismatched donors. An efficient strategy is therefore needed for determining the likelihood that an appropriate donor exists and for deciding which of the donors that have not yet been DR typed should be tested for DR matching with the candidate. We developed a mathematical algorithm and computer program to facilitate the search for a suitable donor by donor race and phenotype. The program provides information on the likelihood of 1) finding at least one HLA-A, -B, -DR phenotypically matched donor, 2) the likelihood of finding at least one DR match among m A, B matched donors who have not yet been DR typed, and 3) the likelihood of an A, B one antigen mismatched donor of a specific phenotype being a DR match with the patient. The mathematical models underlying the program are based on basic population genetics theory and utilize HLA-A, -B, DR haplotype frequencies derived from the NMDP registry. The results of the validation study show that the prediction is highly accurate at the level of broad antigens. The algorithm and program have the potential to assist patients and physicians in optimizing their decisions regarding clinical management and resource allocation on the process of searching for a suitable unrelated bone marrow donor.

Blood Donors↗

PubMed1997

The search for HLA-matched donors: a summary of HLA-A, -B, -DRB1/3/4/5* alleles and their association with serologically defined HLA-A, -B, -DR antigens.

This report summarizes data obtained from several large studies including the WHO HLA Nomenclature Committee, the International Cell Exchange, UCLA, the British Society for Histocompatibility and Immunogenetics Rare Cell Exchange and the National Marrow Donor Program and individual laboratories aimed at identifying a serologic type for specific HLA-A,-B,-DRB allelic products. Alleles that are poorly characterized at the serologic level are indicated and an approach is suggested for obtaining the information needed to clarify their serologic typing. The tables provided will be useful in guiding searches for an unrelated donor in which patient and/or potential donors are typed either by serology or by DNA-based methods and will provide a "dictionary" of potential equivalents between HLA "types" obtained by the two methods.

Alleles↗

PubMed2003

Characterization of two new HLA-B alleles by sequence-based typing: HLA-B0817 and HLA-B1311.

In this brief communication we report the characterization of two new HLA-B variants officially named HLA-B*0817 and HLA-B*1311. The HLA-B*0817 allele was identified in a Caucasoid male candidate for renal transplantation in the North Italy Transplant program. The nucleotidic sequence of exons 2, 3 and 4 of this novel allele is identical to that of HLA-B*0804 except for three point mutations in exon 2: from A to G at position 259, from C to G at position 261 and from G to A at position 302. These mutations are responsible for two aminoacidic substitutions [Asn (r) Glu, codon 63, and Ser (r) Asn, codon 77]. HLA-B*1311 was found in a volunteer donor belonging to National Marrow Donor Program(R). This new variant is identical to that of HLA-B*1301 except for three nucleotide substitutions at positions 353, 355 and 369 leading to two aminoacidic variations from Ile to Thr at codon 94 and from Ile to Leu at codon 95 and a silent mutation at codon 99.

Alleles↗

PubMed2000

The US Navy Tissue Bank: 50 Years on the Cutting Edge.

The US Navy Tissue Bank was established in 1949 by Dr. George Hyatt, an orthopaedic surgeon at the Naval Medical Center in Bethesda, Maryland. The Navy program was the first of its kind in the world and established many of the standards that are followed today. During the 1950s, the identification of appropriate donor criteria for tissue donation, the development of procurement and processing methods, the establishment of a graph registry and documentation and the clinical evaluation of a variety of tissues were pioneered at this facility. Cryopreservation, freeze-drying, irradiation sterilization of tissue, as well as immunological principles of tissue transplantation, were developed during the 50 years of research and development by Navy scientists. Organ preservation, cadaveric bone marrow recovery and immunosuppressive protocols were also developed at the Navy Tissue Bank. The Navy was also instrumental in the establishment of the National Marrow Donor Program and the American Association of Tissue Banks in the US.Although the Navy Tissue Bank has ceased activity after 50 years of excellence, it should be recognized as the first standard setter for the world community of tissue banks.

Journal Article↗

PubMed1997

A national survey of immunization practices following allogeneic bone marrow transplantation.

OBJECTIVES: To describe the frequency and patterns of use of routine childhood and hepatitis B, pneumococcal, influenza, and meningococcal vaccines following allogeneic bone marrow transplantation (BMT). DESIGN, SETTING, AND PARTICIPANTS: Survey of all US transplantation centers participating in the National Marrow Donor Program (NMDP) during 1994. MAIN OUTCOME MEASURES: Use, timing, and total doses of selected vaccines given to patients younger than 7 years and patients aged 7 years or older following allogeneic BMT. RESULTS: Of 66 centers associated with the NMDP, 45 (68%) responded. A total of 97% of centers performing transplants on patients younger than 7 years and 88% of centers performing transplants on patients aged 7 years or older gave either the diphtheria-tetanus vaccine or the diphtheria-tetanus-pertussis vaccine compared with 77% and 58% usage, respectively, of Haemophilus influenza type b conjugate vaccine (P=.03 and .003, respectively). Centers were more likely to administer inactivated poliovirus and measles-mumps-rubella vaccines to patients younger than 7 years than to the older age group (94% vs 73% for poliovirus, P=.02; and 94% vs 70% for measles-mumps-rubella, P=.01). About one half of centers routinely administer hepatitis B vaccine and approximately three quarters immunize with pneumococcal and influenza vaccines. Few programs, regardless of age of bone marrow recipient, use multiple vaccine (> or =2) doses. The number of schedules reported for specific vaccines varied widely (3-11 schedules per vaccine). CONCLUSIONS: Despite convincing evidence that patients lose protective antibodies to vaccine-preventable diseases following allogeneic BMT and accumulating data showing the safety and efficacy of many vaccines after BMT, vaccines are underutilized and schedules vary widely at US transplant centers. National guidelines for optimal doses and timing of vaccines after BMT are warranted.

Adolescent↗

PubMed1994

Stem cell transplantation: past, present and future.

Attempted human allogeneic marrow transplants in the 1950s and 60s were largely unsuccessful. In the past two decades the probability of success has improved steadily depending on the type and stage of disease. Cure rates range from about 90% for nonmalignant diseases transplanted early to 15% for patients with advanced leukemia. Most marrow transplants have involved an HLA matched sibling donor but, more recently, through the National Marrow Donor Program, a matched unrelated volunteer marrow donor can be found for many patients without a family donor. Current research involves new preparative regimens for elimination of malignant cells, better prevention of graft-versus-host disease, and the use of hematopoietic growth factors and cytokines. Autologous transplants, which use the patient's own marrow, are increasing. The hematopoietic stem cell, which is responsible for marrow regeneration after a transplant, has been isolated and characterized. Stem cells for transplantation can now be obtained from the peripheral blood after mobilization of these cells by chemotherapy or hematopoietic growth factors. A variety of technological advances makes it possible to perform transplants with less time in the hospital and a corresponding saving in cost.

Cytokines↗

PubMed1994

Effect of HLA incompatibility in marrow transplantation from unrelated and HLA-mismatched related donors.

Transplants from related donors who share one HLA haplotype and are variably matched with the recipient for HLA-A, B, or DRB1 loci on the unshared haplotype are associated with increased risks of graft failure and graft-versus-host disease (GVHD) that correlate with the degree of HLA mismatch. Survival, however, is not necessarily inferior if recipient incompatibility is limited to one HLA locus. Available methods for post-transplant immunosuppression have not allowed similar success with transplants incompatible for two or three HLA loci. GVHD incidence and severity can be decreased by depletion of donor T cells from the marrow inoculum. However, the potential benefit is offset by increased graft failure and leukemia relapse with no improvement in survival. Since fewer than 30% of the patients in North America or Europe have an HLA-matched sibling and less than 5% have a one HLA-locus mismatched relative, most candidates for an allogeneic marrow transplant are in need of an unrelated donor. As of October 1993, the National Marrow Donor Program (NMDP) has accrued more than 1 million volunteers typed for HLA-A and B, including 200,000 typed for HLA-DR, and has provided donors for more than 2000 transplants. The probability of finding an HLA-A, B, DR match at the initial search has increased from 10-15% in 1987, to 50-55% in 1992. An additional 12% of patients will find a match when available HLA-A and B matched donors are typed for DR, and 20% of patients have a one HLA-locus incompatible unrelated donor. Through an international network of regional registries a search for an unrelated donor can now be conducted among 1.7 million volunteers worldwide. Unrelated donor transplants have allowed long-term disease-free survival of patients with a variety of hematological disorders. When compared to HLA-matched sibling transplants, unrelated donor transplants are associated with an increase in the incidence of graft failure and GVHD. Such an increase may be due to undetected HLA disparities or to non-HLA-linked histocompatibility genes. At our center patients with CML in chronic phase, the most common indication for unrelated donor transplantation, have a 50-55% probability of survival 2-6 years after an unrelated donor transplant, whereas patients with aplastic or refractory anemia have a 25-35% probability of survival.(ABSTRACT TRUNCATED AT 400 WORDS)

Bone Marrow Transplantation↗

PubMed2005

Umbilical cord blood transplantation in adults: results of the prospective Cord Blood Transplantation (COBLT).

The Cord Blood Transplantation study group conducted a prospective study of unrelated cord blood transplantation (CBT) to better define the role of this stem cell source for subjects requiring unrelated allogeneic transplantation. We report on 1 stratum of the study designated for adult subjects. The primary end point of the study was survival at 180 days. Secondary end points included engraftment, graft-versus-host disease, relapse, and long-term survival. Eligibility criteria for malignant and nonmalignant diseases were specified. Subjects with active central nervous system disease, Karnofsky performance status <70%, grade 3 or 4 or primary myelofibrosis, or suitable related donors were excluded. Enrollment required a single cord blood unit containing >10(7) nucleated cells per kilogram of recipient weight and matched at > or =4 HLA-A and -B (low or intermediate resolution) and -DRB1 (high resolution) types. Thirty-four subjects were entered, with a median age of 34.5 years (range, 18.2-55 years). Most subjects (n = 23) had a 4 of 6 match, 10 subjects had a 5 of 6 match, and 1 subject had a 6 of 6 match. Diagnoses at transplantation included acute myelogenous leukemia (n = 19), acute lymphoblastic leukemia (n = 9), chronic myelogenous leukemia (n = 3), myelodysplastic syndrome (n = 1), paroxysmal nocturnal hemoglobinuria (PNH) (n = 1), and non-Hodgkin lymphoma (n = 1); 94% were classified as poor risk according to National Marrow Donor Program criteria. Subjects received total body irradiation/cyclophosphamide (n = 27) or busulfan/melphalan (n = 7) conditioning regimens. Four subjects died before CBT and are described here but are not included in the main analysis. The cumulative incidence rates and median times to neutrophil (500/microL) and platelet (>20,000/microL) engraftment were 0.66 by day 42 (median, 31 days) and 0.35 by day 180 (median, 117 days). The cumulative incidence rate for grade II-IV GVHD was 0.34 by day 100. For the primary end point, survival at 180 days, Kaplan-Meier survival estimates were 0.30 (95% confidence interval, 0.14-0.46) by day 180 after transplantation. To date there are 2 survivors, and both are >36 months from enrollment. A retrospective analysis was performed by using high-resolution HLA-A and -B typing, which revealed that approximately one third of subjects had 1 or more additional HLA mismatches compared with results of low- or intermediate-resolution HLA typing. The findings of high treatment-related mortality and slow engraftment kinetics indicate that CBT should continue to be performed in specialized centers with a research focus on cord blood cells.

Adolescent↗

PubMed2005

The new apheresis and blood and marrow transplantation-related current procedural terminology codes for payment of apheresis and blood and marrow transplantation services.

To address deficiencies in Current Procedural Terminology (CPT) codes that describe many of the clinical services offered to patients, several physicians in the blood and marrow transplantation and apheresis field joined with a coalition including the American Society of Hematology, American Society for Blood and Marrow Transplantation, American Association of Blood Banks, American Society of Clinical Oncology, American Society for Apheresis, National Marrow Donor Program, and American Red Cross to collaborate in addressing these deficiencies by designing new CPT codes. The CPT editorial panel approved 18 new or revised codes. All these codes were given permanent or temporary value by the relative value unit update committee, but not all values were approved by the Centers for Medicare & Medicaid Services (CMS), in particular, the cell-processing codes and the unrelated donor search code. Further discussions addressing these concerns are under way with the CMS. Use of these new codes allows apheresis and transplant centers to charge appropriately for these services. This will help transplant center contracts with CPT codes, with payers more specifically describing services offered to these patients. In turn, this will give better justification for payment. This may allow certain payments for services to increase and help transplant centers better allocate revenue from fixed global case rate payments. Details about the individual codes and their approval process are reviewed in this article.

Blood Component Removal↗

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↗

PubMed2006

The association and linkage of the HLA-A2 class I allele with autism.

Previous research has revealed associations between autism and immune genes located in the human leukocyte antigen (HLA). To better understand which HLA genetic loci may be associated with autism, we compared the class I HLA-A and -B alleles in autistic probands with case control subjects from Caucasian families. The frequency of HLA-A2 alleles was significantly increased in autistic subjects compared with normal allelic frequencies from the National Marrow Donors Program (NMDP) (p = 0.0043 after allelic correction). The transmission disequilibrium test for the A2 allele revealed an increased frequency of inheritance for autistic children (p = 0.033). There were no significant associations of autism with HLA-B alleles; however, the A2-B44 and A2-B51 haplotypes were two times more frequent in autistic subjects. The association and linkage of the class I HLA-A2 allele with autism suggests its involvement in the etiology of autism. Possible roles are discussed for the HLA-A2 association in the presentation of microbial antigen within the central nervous system and/or in the establishment of synaptic and neuronal circuits in the developing brain.

Alleles↗

PubMed2001

The HLA dictionary 2001: a 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 the serologic equivalents of 123 HLA-A, 272 HLA-B, and 155 HLA-DRB1 alleles. The equivalents cover over 64 percent of the presently identified HLA-A, -B, and -DRB1 alleles. The dictionary is an update of the one published in 1999 (Schreuder GMTh, Hurley CK, Marsh SGE, Lau M, Maiers M, Kollman C, Noreen H. The HLA dictionary 1999: a 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. Tissue Antigens 54:407, 1999) and also includes equivalents for HLA-C, DRB3, DRB4, DRB5, and DQB1 alleles. The data summarize information obtained by the WHO Nomenclature Committee for Factors of the HLA System, the International Cell Exchange (UCLA), the National Marrow Donor Program (NMDP), and individual laboratories. In addition, a listing is provided of alleles which are 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. These equivalents will also serve typing and matching procedures for organ transplant programs where HLA typings from donors and from recipients on waiting lists represent mixtures of serologic and molecular typings. The tables with HLA equivalents and a questionnaire for submission of serologic reaction patterns for poorly identified allelic products will also be available on the WMDA web page: www.worldmarrow.org.

Alleles↗