From the Rhesus phenotype of the father and mother, it is possible to guess the likely genotype and phenotype for their child.
Background
Rh combinations for c/C & d/D & e/E in a gene = (2 * 2 * 2 ) = 8
gene combinations for 2 genes = (8 * 8) = 64 possible
• with duplicates eliminated = 8 + 7 + 6 + 5 + 4 + 3 + 2 + 1 = 36 genotype combinations
for each of the Rhesus antigens:
(1) 10 genotypes are negative for the antigen
(2) 16 genotypes are heterozygous for the antigen
(3) 10 genotypes are homozygous for the antigen
There are 18 phenotypes for these genotypes:
(1) for c, C, e and E: 6 phenotypes are homozygous, 6 are heterozygous and 6 are negative for the antigen
(2) for D: 9 phenotypes are positive and 9 are negative
Most probable genotype (MPG) for given phenotype:
(1) 1 option: 8
(2) 2 options: 5
(3) 3 options: 4
(4) 4 options: 0
(5) 5 options: 0
(6) 6 options: 1
For each Rhesus antigen:
(1) percent heterozygous = percent complement antigen heterozygous
(2) percent negative = percent complement antigen homozygous
(3) percent homozygous = percent complement antigen negative = 100% - (percent homozygous for complementary antigen) - (percent heterozgyous for complementary antigen)
If points are assigned for positive reactions with antisera:
• D: 32 points
• c: 16 points
• C: 8 points
• e: 4 points
• E: 2 points
and summated, values from 10 - 62 can be generated which can be mapped to a phenotype.
Frequency of Rh Genes and Phenotypes in Different Populations
|
Gene |
Asian |
Black |
Native American |
White |
|
cde |
3% |
26% |
11% |
37% |
|
cdE |
0% |
0% |
1% |
1% |
|
cDe |
3% |
44% |
2% |
4% |
|
cDE |
21% |
11% |
34% |
14% |
|
Cde |
2% |
2% |
2% |
2% |
|
CdE |
0% |
0% |
0% |
0% |
|
CDe |
70% |
17% |
44% |
42% |
|
CDE |
1% |
0% |
6% |
0% |
|
total |
100% |
100% |
100% |
100% |
|
Phenotype |
Gene 1 |
Gene 2 |
Asian |
Black |
Native American |
White |
|
cCDE |
cDE |
CDE |
|
|
4.1% |
0.07% |
|
|
cDE |
CdE |
|
|
|
0.0% |
|
|
cdE |
CDE |
|
|
|
0.006% |
|
cCDe |
cDe |
CDe |
4.2% |
15.0% |
1.8% |
2.1% |
|
|
cDe |
Cde |
|
1.8% |
|
0.2% |
|
|
cde |
CDe |
4.2% |
8.8% |
9.7% |
31.1% |
|
cCdE |
cdE |
CdE |
|
|
|
0.0% |
|
cCde |
cde |
Cde |
0.12% |
0.14% |
0.4% |
0.7% |
|
cCDeE |
cDE |
CDe |
29.4% |
3.7% |
29.9% |
11.8% |
|
|
cDE |
Cde |
0.8% |
0.4% |
1.4% |
Specialty: Clinical Laboratory ICD-10: , |
