The H Antigen

	Genetics Home
Blood Group Inheritance and Immunogenetics Blood Group Inheritance and Immunogenetics Blood, Antigens and Antibodies Antigen and Antibody Reaction A, B, AB and O Blood Groups Multiple Allelic Inheritance of A, B, AB and O Blood types RH Blood Type and its Inheritance Genetics of RH+ Blood Type

The H Antigen

The H Antigen
In individuals with genotypes HH or Hh, a so called H-substance is present on the erythrocytes and may be demonstrated by agglutination by anti-H serum. The H antigen is believed to be an intermediate between a precursor mucopolysaccharide and antigens A and B to which it is partly converted in the presence of genotypes LA- or LB-. So long as they are of genotype H-, group individuals produce antigens A and H, group B person test positively for antigens Band H, and group AB persons produce antigens A, B, and H. Individuals of group 0 produce only H antigen if their genotype is LOLOHH or LOLOHh, but none of these antigens if the genotype is LOLOhh.

Substance	Precursor				Mucopolysaccharide
	↓				↓
H, h genotypes:	(HH or Hh)				(hh)
	↓				↓
Substance	H Substance				Unchanged precursor
	↓				↓
	↓	↓	↓	↓	↓	↓	↓	↓
L^A,^B,1 genotypes:	L^AL^A	L^BL^B	L^AL^B	L^OL^O	L^A-	L^B-	L^AL^B	L^OL^O
	L^AL^O	L^BL^O	↓	↓	↓	↓	↓	↓
	↓	↓	↓	↓	↓	↓	↓	↓
	AH	BH	ABH	H	None

Persons whose blood gives no reaction with anti-A, anti-B, or anti-H belong to the very rare Bombay phenotype, so named because it was first described in a small group from that city. Chemical tests have revealed the fact that the alpha-L-fucosyl residue is associated with H substance specification.

	Genetics Home
Human blood Phenotypes The H Antigen The Secretor Trait The Lewis System The M-N Series Antigenic Substances in Other Organisms Genetics of Serum Proteins

Home | Site map | Submit Article | Directory | Search