Blood Groups

Blood Group Systems.

The following list shows the blood group system names and symbols. (The column of derivations of names of blood group systems is provided for background interest^1,2,9,11-14 [also Geoff Daniels, PhD, written communications, May 13 and 17, 2004].)

The ISBT prefers an all-capital style for blood group system symbols³ (see “ISBT Name and Number” in this section).

The following are examples of usage:

ABO incompatibility

A cell

type AB recipient

type O donor

Hemolytic disease of the newborn primarily occurs from incompatibilities of the Rh, ABO, or Kell blood groups.

Antigens.

Antigen terms use single or dual letters, often with a qualifier that is a letter (usually superscript) or number (subscript or typeset on the line).

A, A₁, A₂, A_x, B

Cr^a

Fy^a, Fy^b

He

Jk^a, Jk^b

K, k

Kp^a, Kp^b, Ku, Js^a, Js^b

K11, K12, K13, K14, Km

Le^a, Le^b, Le^bH, ALe^b, BLe^b

Lu^a, Lu^b

Lu3, Lu4, Lu5, Lu6

P¹

Sc1, Sc2

Xg^a

The Rh system historically has used 3 alternative schemes: the Rh-Hr nomenclature, the CDE nomenclature, and the numerical nomenclature.⁷ Terms from the first, eg, rh′, hr″, rh^x, Rh^A, are appropriate in historical discussions, but otherwise, the CDE and numerical nomenclatures are favored:

D, C, E, c, e, f

Ce, C^w, C^x… BARC

or

Rh1, Rh2, Rh3, Rh4, Rh5, RH6

RH7, RH8, RH9… RH52

The following are examples of antigen-term usage:

anti-Jk^a alloantibody

Rh(D) incompatibility

human monoclonal anti-D antibodies

Studies using anti-Ch and anti-Rg antisera have demonstrated Ch and Rg determinants on complement component C4.

Phenotypes.

In phenotypic expressions—terms that describe an individual’s blood group or type—the presence or absence of an antigen is often indicated by a plus or minus sign:

Antigen: M

Phenotype: M+

M+N+S−s+ erythrocytes

M+N+S−s+ phenotype

Lowercase letters that were superscripts in the antigen terms are set on the line in parentheses in phenotypic terms.

Antigen: Lu^b

Phenotype: Lu(b+)

More than 98% of the Western population is Lu(b+).

If the numerical terminology is used for the antigen, a colon is added in the phenotype.

Antigen: Sc1

Phenotype: Sc:1

the Sc:1,−2,3 phenotype

Other sample phenotypic terms include the following:

Fy(a−b+), Fy(a+b−), Fy(a−b−)

Jk(a−b+), Jk(a+b−), Jk(a+b+)

K+k−, Kp(a−b+), Js(a−b+)

Le(a−b+), Le(a+b−), Le(a−b−)

Lu(a−b+), Lu(a+b−), Lu(a+b+)

M+N+, M+, N−, M−N+, S+s+, S+s−, S−s+

P₁, P₂, P₁^k, P₂^k

Xg(a+), Xg(a−)

the silent phenotype Le(a−b−)

A superscript w can indicate a weak reaction:

M+^w

K+^w

Fy(a+^w)

The ABO system is an exception: its phenotypic terms do not feature plus or minus signs; A (not A+) indicates A erythrocyte antigens; O (not A− B−) indicates the absence of A and B antigens:

Groups: O, A, B, AB, O_h, O_h^A

Subgroups: A₁, A₂, A₁B, A₂B

O_h^A individuals do not express the H determinant but do have the A allele.

Terms for Rh phenotypes, which do not feature plus and minus signs, are also in use:

D-positive (Rh positive)

D-negative (Rh negative)

DccE, DCce

RH:1,2,3

Rh_null

Absence of C, c, E, and/or e antigens is indicated with 1 or 2 minus signs¹⁴:

Dc−

D− −

Usage note: Terms such as O+ (“O positive”), A+, and AB− are common parlance as shorthand for blood of the ABO system and its Rh specificity. However, in scientific articles, use standard terms that specifically indicate Rh status:

O Rh-positive

O Rh+

or more specific designations of phenotype:

group B, D-negative

group A, Rh D-positive

In a blood group profile, elements from different systems may be separated by commas, as above, or, for more complex specificities, with semicolons:

The patient’s blood was group B, Rh positive, D+ C+ c+ E− e+; M+ N+ S− s+; P1+; Le(a−b−); K− k+; Fy(a−b+); Jk(a+b−).^15(p846)

Note that in phenotypic expressions commas do not appear within elements of the same blood group system:

D+ C+ c+ E− e+

Not: D+, C+, c+, E−, e+

Commas may be dispensed with between different blood group systems in brief expressions:

K+Fy(a+)

Genes.

As with International Standard Gene Nomenclature (the “HUGO” recommendations; see 15.6.2, Genetics, Human Gene Nomenclature), ISBT gene terms are italicized. Traditional blood-group gene symbols often mixed uppercase and lowercase. However, symbols recommended by ISBT, like those of HUGO, use all capital letters.

The following list^3,4,9,16 shows gene symbols associated with blood group systems.

Gene symbols expressed according to ISBT⁴ or HUGO¹⁶ are preferred to traditional symbols.

Parenthetic synonyms are helpful:

BSG(formerly OK)

ERMAP(also called SC)

The Lutheran inhibitor gene is expressed as follows:

In(Lu) [traditional]

INLU [standard]

Do not confuse In with the traditional Indian blood group gene symbol, In (recommended gene symbol: CD44).

Alleles.

The italicized blood group symbol—ABO, MNS, RH, etc—is used for alleles (which are also distinguished by an asterisk and number). In the following example, compare the gene symbol and an allele term from the same blood group:

SC*1 [allele]

ERMAP [gene symbol]

Note that qualifiers that are subscripts in antigen terms are superscripts in allelic terms, eg, A₁ antigen, A¹ allele). The following are examples of genotypic terms.

A¹O, A¹A¹, A¹B, OO

MN, MM, NN, MSNs

DCe/DCe (R¹R¹)

DcE/dce (R²r)

dce/dce (rr)

D− −/D− −

Lu^aLu^a, Lu^bLu^b, Lu^aLu^b

Lele, LeLe, lele

Fy^aFy^a, Fy^bFy^b, FyFy

Kk, Kp^aKp^b, Js^bJs^b

Jk^aJk^a, Jk^bJk^b, Jk^aJk^b

Xg^aXg^a, Xg^aXg, XgXg

Xg^aY, XgY

For expressing alleles, the ISBT gives an option, eg, either Fy^a or FY*1 (with appropriate superscripts and italics). Mixing the 2 styles, however (eg, FY*A), is not appropriate (Geoff Daniels, PhD, written communications, May 13 and 17, 2004).