HLA-B61 explained

HLA-B61 (B61) is an HLA - B serotype. B61 is a split antigen serotype that recognizes certain B40 serotypes.^{[1] [2]}

Serotype

B61, B40, B60 serotype recognition of some HLA B*40 allele-group gene products^[3]

B*40	B61	B40	B60	Sample
allele	%	%	%	size (N)
4002	80	6	8	1460
4003	62		23	31
4004	47		12	57
4006	75	5	5	585

Notes and References

1. Ways JP, Lawlor DA, Wan AM, Parham P . A transposable epitope of HLA-B7, B40 molecules . Immunogenetics . 25 . 5 . 323–8 . 1987 . 2437025 . 10.1007/BF00404425 .
2. 2848993 . 2010 . Marsh . S. G. . Nomenclature for factors of the HLA system, 2010 . Tissue Antigens . 75 . 4 . 291–455 . Albert . E. D. . Bodmer . W. F. . Bontrop . R. E. . Dupont . B. . Erlich . H. A. . Fernández-Viña . M. . Geraghty . D. E. . Holdsworth . R. . Hurley . C. K. . Lau . M. . Lee . K. W. . Mach . B. . Maiers . M. . Mayr . W. R. . Müller . C. R. . Parham . P. . Petersdorf . E. W. . Sasazuki . T. . Strominger . J. L. . Svejgaard . A. . Terasaki . P. I. . Tiercy . J. M. . Trowsdale . J. . 20356336 . 10.1111/j.1399-0039.2010.01466.x .
3. Robinson J, Waller MJ, Fail SC, Marsh SG . The IMGT/HLA and IPD databases . Hum. Mutat. . 27 . 12 . 1192–9 . 2006 . 16944494 . 10.1002/humu.20406 . free .