Skip to main content

Willy A. Flegel, MD

Willy A. Flegel, MD
Chief, Laboratory Services Section
Department of Transfusion Medicine

Academic Degrees
MD, University of Frankfurt/Germany
Privatdozent, University of Ulm/Germany


Phone: 301-594-7401

Back to Senior Staff Directory

NIH Clinical Center Senior Staff

Willy A. Flegel, MD


Bill Flegel earned his medical degree and received a Doctor of Medicine by research (, magna cum laude) at the University of Frankfurt, trained in transfusion medicine at the University of Ulm and performed post-doctoral research at University of California at San Diego. He was appointed head of the Immunohematology Department at the German Red Cross Blood Center Ulm and a member of the Medical Faculty, University of Ulm, as Associate Professor (Privatdozent) in 1998 and Professor (apl. Professor) in 2005. He is Adjunct Professor, Georgetown University Medical Center, Washington DC and Visiting Professor, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.

Dr. Flegel has been actively involved in blood transfusion medicine since 1986 and at the forefront of research on Rh antigens since 1994. His many professional activities include founding and coordinating the German Rare Donor Program 1999 – 2009; serving as a member of the International Society of Blood Transfusion (ISBT) Working Parties for Rare Donors 2000 – 2010, on Red Cell Immunogenetics and Blood Group Terminology since 2004 and on Immunohematology since 2014; and inventing for patents in the field of molecular immunohematology. He serves as Associate Editor of Transfusion, Senior Editor of J Transl Med and on the editorial boards of Blood Transfusion and Chin Med J. He has published more than 140 articles in scientific journals, authored a medical-legal text book on transfusion medicine and has written several book chapters.

Dr. Flegel came to the NIH Clinical Center Department of Transfusion Medicine (DTM) in 2009 as Chief, Laboratory Services Section. In this role, he directs the Transfusion Services (TSL) and HLA Laboratories. During his tenure, the TSL expanded genotyping for RBC antigens and the HLA Laboratory established KIR gene expression assays. Research interests include blood group genotyping; relationship of genotype, phenotype and function of blood group proteins; stem cell surface antigens in vivo and during ex vivo expansion; and immunogenetics in hematopoietic stem cell transplantation.


NIH Clinical Center Director's Award, 2015 (Patient Care), 2012 (Patient Care) and 2010 (Strategic Initiative); Honorary Member of the Swiss Association for Transfusion Medicine, 2005; Philip Levine Award of the German Society for Transfusion Medicine and Immunohematology, 2004.

Selected Publications


Lippert H-D, Flegel WA. Kommentar zum Transfusionsgesetz (TFG) und den Hämotherapie-Richtlinien. XXXIX, 521 pages. Springer, Berlin 2002


Flegel WA, Wagner FF. Blutgruppen: Alloantigene auf Erythrozyten. In: Kiefel V (Ed.) Transfusionsmedizin und Immunhamatologie. Springer, Berlin 2010, 4th edition

Flegel WA. Transfusion. In: Delves PJ, Roitt IM (Eds.) Encyclopedia of Immunology. Academic Press, London 1999, 2nd edition


Klein HG, Flegel WA, Natanson C. Red blood cell transfusion: precision vs imprecision medicine. JAMA 314: 1557 – 1558, 2015

Flegel WA, Natanson C, Klein HG. Does prolonged storage of red blood cells cause harm? Br J Haematol 165: 3 – 16, 2014

Flegel WA, Roseff SD, Tholpady A. Phasing-in RHD genotyping. Arch Path Clin Lab 138: 585 – 588, 2014

Flegel WA, Johnson ST, Keller MA, Klapper EB, Khuu HM, Moulds JM, Seltsam AW, Stack G, St-Louis M, Tormey CA, Wagner FF, Weinstock C, Yazer MH, Denomme GA. Molecular immunohematology round table discussions at the AABB Annual Meeting, Boston 2012. Blood Transfusion 12: 280 – 286, 2014

Flegel WA. Molecular genetics and clinical applications for RH. Transf Apher Sci 44, 81 – 91, 2011

Flegel WA. Immunogenicity reloaded. Blood 114, 3979 – 3980, 2009

Denomme GA, Flegel WA. Applying molecular immunohematology discoveries to standards of practice in blood banks: now is the time. Transfusion 48, 2461 – 2475, 2008

Flegel WA. Will MICA glitter for recipients of kidney transplants? N Engl J Med 357, 1337 - 1339, 2007

Flegel WA. Homing in on D antigen immunogenicity. Transfusion 45, 466 – 468, 2005

Northoff H, Flegel WA. Genotyping and phenotyping: the two sides of one coin. Infusionsther Transfusionsmed 26, 5, 1999


Flegel WA, Gottschall JL, Denomme GA. Integrating red cell genotyping into the blood supply chain: a population-based study. Lancet Haematol 2: e282 – e288, 2015

Flegel WA, Gottschall JL, Denomme GA. Implementing mass-scale red cell genotyping at a blood center. Transfusion 55: 2610 – 2615, 2015

Srivastava K, Almarry NS, Flegel WA. Genetic variation of the whole ICAM4 gene in Caucasians and African Americans. Transfusion 54: 2315 – 2324, 2014

Rujirojindakul P, Flegel WA. Applying molecular immunohematology to regularly transfused thalassemic patients in Thailand. Blood Transfusion 12: 28 – 35, 2014

Schmid P, Flegel WA. Codon usage in vertebrates is optimized for a low risk of acquiring nonsense mutations. J Transl Med 9: 87, 2011

Schäfer R, Schnaidt M, Klaffschenkel RA, Siegel G, Schüle M, Rädlein MA, Hermanutz-Klein U, Ayturan M, Buadze M, Gassner C, Danielyan L, Kluba T, Northoff H, Flegel WA. Expression of blood group genes by mesenchymal stem cells. Br J Haematol 153: 520 – 528, 2011

Schwartz, S, Vergoulidou,M, Schreier, E, Loddenkemper,C, Reinwald,M, Schmidt-Hieber M, Flegel WA, Thiel E, Schneider T. Norovirus gastroenteritis causes severe and lethal complications after chemotherapy and hematopoietic stem cell transplantation. Blood 117, 5850 – 5856, 2011

Fasano RM, Monaco A, Riehm Meier E, Pary P, Lee-Stroka AH, Otridge J, Klein HG, Marincola FM, Kamani NR, Luban NLC, Stroncek D, Flegel WA. RH genotyping in a sickle cell disease patient contributing to hematopoietic stem cell transplantation donor selection and management. Blood 116, 2836 – 2838, 2010

Flegel WA, von Zabern I, Doescher A, Wagner FF, Strathmann KP, Geisen C, Palfi M, Písacka M, Poole J, Polin H, Gabriel C, Avent ND. D variants at the RhD vestibule in the weak D type 4 and Eurasian D clusters. Transfusion 49, 1059 – 1069, 2009

Flegel WA, von Zabern I, Wagner FF. Six years' experience performing RHD genotyping to confirm D– red blood cell units in Germany for preventing anti-D Immunizations. Transfusion 49, 465 – 471, 2009

Lüttringhaus TA, Cho D, Ryang DW, Flegel WA. A simple RHD genotyping strategy for D– East Asian persons applied to Korean blood donors. Transfusion 46, 2128 - 2137, 2006

Wagner FF, Moulds JM, Flegel WA. Genetic mechanisms of Rhesus box variation. Transfusion 45, 338 – 344, 2005

Wagner FF, Poole J, Flegel WA. Scianna antigens including Rd are expressed by ERMAP. Blood 101, 752 - 757, 2003

Wagner FF, Eicher NI, Jørgensen JR, Lonicer CB, Flegel WA. DNB: a partial D with anti-D frequent in Central Europe. Blood 100, 2253 – 2256, 2002

Wagner FF, Ladewig B, Angert KS, Heymann GA, Eicher NI, Flegel WA. DAU allele cluster of the RHD gene. Blood 100, 306 – 311, 2002

Flegel WA, ÄŒurin-Šerbec V, Delamaire M, Donvito B, Ikeda H, Jørgensen J, Kumpel B, Le Pennec P-Y, Písacka M, Tani Y, Uchikawa M, Wendel S, Wagner FF. Rhesus index and antigen density: An analysis of the reproducibility of flow cytometric determination (Section 1B: Rh flow cytometry – Coordinator's report). Transf Clin Biol 9, 33 – 42, 2002

Wagner FF, Frohmajer A, Flegel WA. RHD positive alleles in D negative whites. BMC Genetics 2, 10, 2001

Wagner FF, Flegel WA: RHD gene deletion occurred in the Rhesus box. Blood 95, 3662 - 3668, 2000

Wagner FF, Frohmajer A, Ladewig B, Eicher NI, Lonicer CB, Müller TH, Siegel MH, Flegel WA. Weak D alleles express distinct phenotypes. Blood 95, 2699 - 2708, 2000

Flegel WA, Khull SR, Wagner FF. Primary anti-D immunization by weak D type 2 RBCs. Transfusion 40, 428 - 424, 2000

Flegel WA, Besenfelder W, Wagner FF. Predicting a donor's likelihood of donating within a preselected time interval. Transfusion Medicine 10, 181 - 192, 2000

Wagner FF, Gassner C, Müller TH, Schönitzer D, Schunter F, Flegel WA. Molecular basis of weak D phenotypes. Blood 93, 385 - 393, 1999

Wagner FF, Gassner C, Müller TH, Schönitzer D, Schunter F, Flegel WA. Three molecular structures cause Rhesus D category VI phenotypes with distinct immunohematologic features. Blood 91, 2157 - 2168, 1998

Wagner FF, Flegel WA. Polymorphism of the h allele and the population frequency of non-functional alleles. Transfusion 37, 284 - 290, 1997

Wagner, F.F., Flegel, W.A.: Toxic epidermic necrolysis. N Engl J Med 334, 922, 1996

Wagner FF, Flegel WA. Transfusion-associated graft-versus-host disease: risk in transfusions due to homozygous HLA-haplotypes. Transfusion 35, 284 - 291, 1995

Flegel WA, Singson AW, Margolis JA, Bang AG, Posakony JW, Murre C. Dpbx, a new homeobox gene related to the human proto-oncogene pbx1: Molecular structure and developmental expression. Mech Dev 41, 155 - 161, 1993

Kniep B, Flegel WA, Northoff H, Rieber EP. CDw60 antigens of human leukocytes: Structural characterization and cellular distribution. Blood 82, 1776-1786, 1993

Flegel WA, Müller F, Däubener W, Fischer H-G, Hadding U, Northoff H. Cytokine response by human monocytes to Clostridium difficile toxin A and toxin B. Infect Immun 59, 3659 - 3666, 1991

Flegel WA, Wölpl A, Männel DN, Northoff H. Inhibition of endotoxin-induced activation of human monocytes by human lipoproteins. Infect Immun 57, 2237 - 2245, 1989

NOTE: PDF documents require the free Adobe Reader.

This page last updated on 05/02/2018

You are now leaving the NIH Clinical Center website.

This external link is provided for your convenience to offer additional information. The NIH Clinical Center is not responsible for the availability, content or accuracy of this external site.

The NIH Clinical Center does not endorse, authorize or guarantee the sponsors, information, products or services described or offered at this external site. You will be subject to the destination site’s privacy policy if you follow this link.

More information about the NIH Clinical Center Privacy and Disclaimer policy is available at