RhD antigen frequency is most common in Asians (99%) and is slightly less common in Blacks (92%) and Caucasians (85%). (1)

Most D-positive phenotypes have a conventional RhD protein; however variations in protein structure can result in either a weak D or partial D phenotype (1-2% of Caucasians). (2) Of note, patients with D variant phenotypes may produce anti-D if immunised with Rh positive red cells and in this situation, it is recommended they be transfused with Rh negative red cells.

Clinically, weak D individuals of types 1, 2, 3, 4.0, 4.1 and 5 can be treated as Rh positive and be transfused with Rh positive red cells, while patients with weak type 4.2-11 and 15 should be treated as Rh negative and transfused with Rh negative red cells. (3, 4)

Partial D individuals can have different epitope expression and induce specific antibody production. As a result, they should be considered Rh negative and transfused with Rh negative red cells.(3, 4)

RhD negative phenotype is most common in Caucasians (15%), less common in Blacks (8%) and rare in Asians (1%). (1)
 

Classification of Rh Phenotype and Genotype

Serology results from testing red cells with the five main Rh anti-sera, the Rh phenotype and probable RH genotype are shown in the following table:

Rh Positive

Serology results and combined data	Phenotype	Probable genotype	Shorthand symbol	Approximate % frequency in Australia	Other possible genotypes
D+ C+ E- c+ e+	CcDee	CDe/cde	R1r	35.3	CDe/cDe cDe/Cde
D+ C+ E- c- e+	CCDee	CDe/CDe	R1R1	17.5	CDe/Cde
D+ C+ E+ c+ e+	CcDEe	CDe/cDE	R1R2	12.9	CDe/cdE cDE/Cde CDE/cde cDe/CDE cDe/CdE
D+ C- E+ c+ e+	ccDEe	cDE/cde	R2r	12.4	cDE/cDe cDe/cdE
D+ C- E+ c+ e-	ccDEE	cDE/cDE	R2R2	2.4	cDE/cdE
D+ C- E- c+ e+	ccDee	cDe/cde	R0r	1.6	cDe/cDe

Rh Negative

Serology results and combined data	Phenotype	Probable genotype	Shorthand symbol	Approximate % frequency in Australia	Other possible genotypes
D- C- E- c+ e+	ccdee	cde/cde	rr	16.7
D- C+ E- c+ e+	Ccdee	Cde/cde	r’r	0.5
D- C- E+ c+ e+	ccdEe	cdE/cde	r”r	0.7

Notes: Frequencies are based on blood group statistics of Australian blood donors; Cells giving a positive reaction with anti-C may be further subdivided by testing with anti-Cw; Other Rh genotypes may be found but all have a frequency of <0.2%.
 

References 

1. Dean L.Blood Groups and Red Cell Antigens [Internet]. Bethesda (MD): National Center for Biotechnology Information (US): 2005. Chapter 7, The Rh blood group. Available from: http://www.ncbi.nlm.nih.gov/books/NBK2269/
2. Reid ME et al. The Blood Group Antigen Facts Book. 3^rd edition. Elsevier, London, 2012
3. Rizzo C et al. Weak D and partial D: our experience in daily activity. Blood Transfus. 2012 Apr; 10(2): 235-236
4. Daniels G. Variants of RhD – current testing and clinical consequences. British Journal of Haematology 2013; 161: 461-470