Xg antigen system
Blood group system
From Wikipedia, the free encyclopedia
The XG antigen is a red blood cell surface antigen discovered in 1962[1] by researchers at the MRC Blood Group Unit.[2]
The PBDX gene that encodes the antigen is located on the short arm of the X chromosome.[3][4] Since males normally have one X chromosome they are considered hemizygotes. Since women have two copies of the gene and could be heterozygotic for the presence or absence of the functioning gene they could (through the process of lyonisation) express the functioning protein on just some of their red blood cells.[citation needed]
Clinical diagnostic
Clinical testing in patient care for Xg antigens follows published minimum quality and operational requirements,[5] similar to red cell genotyping for any of the other recognized blood group systems. Molecular analysis can identify gene variants (alleles) that may affect Xg antigens expression on the red cell membrane.
Frequency
| Population frequencies of Xa[6] | ||||||
|---|---|---|---|---|---|---|
| Population | Sample N |
Xg % | ||||
| Australian Aborigines | 352 | 79 | ||||
| Chinese, mainland | 171 | 60 | ||||
| North Europeans | 5,388 | 66 | ||||
| Indians, Bombay | 100 | 65 | ||||
| Israelis | 201 | 66 | ||||
| American Indians | 308 | 77 | ||||
| New-Guineans | 263 | 85 | ||||
| New York's Afro-Americans | 219 | 55 | ||||
| Sardinians | 322 | 76 | ||||
| Taiwan Chinese | 178 | 53 | ||||
| Taiwan Aborigines | 164 | 38 | ||||
