Some Notes On The Rh And Hr Factors - Ncbi
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1
2
3Vol.
67, No.
1
Some Notes
on
the Rh and Hr Factors *
MARJORIE L. HUNT, M.P.H., and S. P. LuCIA, M.D., San Francisco
T
HE literature
on
the subject of the Rh-Hr factors
and the antibodies
they
incite is
not
only
com-
plex, but
in
some
instances it is confusing and
con-
tradictory. Often the line of demarcation between
hypothesis and fact is
not
clearly drawn
so
that it
becomes extremely difficult
to
determine the potential
significance of the available information. The follow-
ing discussion
is
an
attempt to present the
nomen-
clatures of Race and Wiener in
a
form
easily
com-
prehensible
to
a
person
not
acquainted with the
subject and
at
the
same
time
to
indicate the
impor-
tance
and usefulness of
tests
for Rh-Hr sensitization.
Rh and Hr Factors:
The Rh factor,
present
in the red blood corpuscles
of
at
least 85
per
cent
of the random white popula-
tion, is
an
inherited characteristic, and like the
Landsteiner A-B-O agglutinogens, is
a
permanent
consistuent of the red blood corpuscles of
an
indi-
vidual. The Rh-positive population
may
be further
subdivided into eight phenotypic
groups
by
means
of various combinations of the three Rh factor
genes,
called C, D, and E by Race, and Rh',
Rho
and Rh"
by Wiener. These factors
are
transmitted in the usual
Mendelian
manner
and
occur as
"allelomorphic
pairs."t
The capital letters C, D, and
E indicate domi-
nant
antigenic characteristics (Rh factors) whose
"allelomorphs" (Hr factors) would be indicated by
the small letters,
c,
d, and
e
(according
to
Race)
and Hr',
Hro
and Hr" (according
to
Wiener).
In
this
manner
the genetic possibilities of homozygous
and heterozygous individuals
may
be determined.
The three Hr factors,
c,
d, and
e, may
also
occur
singly
or
in combination. A
reciprocal relationship
probably exists
between Rh and Hr-for
example,
if
gene
C is absent, then
gene
c
must
be
present,
and
likewise D-d and
E
-.
The factor Hr is
apparently
less antigenic and therefore usually
of lesser clinical
importance than
the factor Rh.
The nomenclatures of Race
t
and of Wiener
there-
fore
may
be represented schematically
for
genotypic
§
incidence in the following
manner:
*
From the Blood
Grouping Laboratory,
Subdivision of
Preventive Medicine, Division of Medicine, University
of
California Medical
School,
San Francisco.
t
This term
is
used with reservations. For a pertinent
discussion of the subject consult references
1
and 5.
*
Race considers that the factors
C-c,
D-d,
and
E-e
occur
together within the red blood corpuscle
and the
presence
of
any one
or more
of the three dominant factors
would therefore determine the
phenotypic
characteristic
of
Rh-positive
individuals; the absence of all three domi-
nant factors would indicate the
Rh-negative
individual.
§ Rh',
Rho,
Rh-,
Rh1,
and Rh2 include the incidence of the
pure
phenotypic
as
well
as
the
genotypic
combinations.
Rh,Rh2
(14.5%))
Rh1 (54.0%go)
Rh2
(15.0%So)
Rh-positive
Rh'
(1.0%)
Rh,
(2.0%0)
Rh"
(0.5%o)
(87.0%)
C
D
E
c
d
e
Rh-negative
Hr'
Hro
Hr"
(13.0%)
Since genes occur in pairs, one set inherited from
each parent, any combinations of
.CD]
are possible
as are shown in Chart I.
Interpretation
of
Reactions
of
Red Blood
Corpuscles with Specific Antisera:
Since the red blood corpuscles of 85 per cent of
the random white population contain the D
(Rho)
factor-Rh antiserum specific for D is most com-
monly used in testing for the presence of the Rh
factor
in blood specimens of unknown Rh charac-
teristic. If the exact phenotypic character of the
blood is desired, it is necessary also to use Rh anti-
sera specific for C (Rh') and E (Rh") factors. Anti-C
will agglutinate 70 per cent, and anti-E will agglu-
tinate 30 per cent of the bloods of a random white
population.
Anti-C sera will react with all red blood corpuscles
containing C factor. Likewise anti-D or anti-E will
react with all corpuscles containing D or E factors,
respectively.
Anti-c sera will react with all red blood corpuscles
containing c factor. Likewise anti-d or anti-e will
agglutinate all cells containing d or e factors, re-
spectively.
Hr sera are sometimes used to determine homo-
zygosity of a husband; for example, if the husband
is type Rh' (Cde) it may be useful to know whether
he is homozygous or heterozygous for the C factor,
that
is
Cde
or
c-d
.
If he is
homozygous
his red blood
Cde
cde
corpuscles will
not
be agglutinated by
anti-c
(Hr')
serum since he does not contain
the
c
factor.
Rh-Antibodies:
An individual whose red blood corpuscles lack a
specific Rh factor
may become sensitized when ex-
posed
to
such
a
factor
during
pregnancy
or
following
blood transfusions. An Rh negative individual may
14
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