The JR blood group system (ISBT 032): molecular characterization of three new null alleles.
BACKGROUND
Jr(a) (ISBT 901005) is a high-prevalence antigen unassigned to a blood group system. People lacking this antigen have been found in all populations studied but most commonly in Asians. Two recent reports established that ABCG2-null alleles encode the Jr(a-) phenotype and these studies provided the impetus to study other Jr(a-) individuals.


METHODS
Blood samples were part of our rare donor-patient collection. DNA was isolated and analyzed by standard techniques.


RESULTS
In samples from 13 Jr(a-) study subjects, we found six alleles with nonsense nucleotide changes, three (c.784T, c.1591T, and c.337T) were novel. Twelve of the samples were homozygous for nonsense single-nucleotide polymorphisms (SNPs): eight were c.376T, two were c.706T, one was c.784T, and one was c.1591T. Each of these alleles predicts a truncated ABCG2 product, Gln126Stop, Arg236Stop, Gly262Stop, and Gln531Stop, respectively. One study subject was heterozygous for two nonsense SNPs: c.337C/T (Arg113Stop) and c.736C/T (Arg246Stop).


CONCLUSIONS
Jr(a) is the sole antigen in the newly established JR blood group system (ISBT 032001). The previous ISBT designation (901005) is now obsolete. Since ABCG2null alleles define the Jr(a-) phenotype, an explanation for why no antithetical low-prevalence antigen to Jr(a) has been found, and also why anti-Jr(a) made by people with any of these JRnull alleles are mutually compatible has been determined. Based on our findings DNA-based genotyping can be developed to replace the serologic methods that are currently used to identify Jr(a-) blood donors.
Laboratory of Immunochemistry, New York Blood Center, New York, New York 10065, USA.
Kim
K
Hue-Roye
Christine
C
Lomas-Francis
Gail
G
Coghlan
Teresa
T
Zelinski
Marion E
ME
Reid
D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000483:Alleles; D001789:Blood Group Antigens / Q000235:genetics*; D006801:Humans; D009363:Neoplasm Proteins / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA
C116614:ABCG2 protein, human; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D001789:Blood Group Antigens; D009363:Neoplasm Proteins