Types Edit

The Diego system is named after a pair of types, Diegoa (Dia) and Diegob (Dib), which differ by one amino acid in the AE1 glycoprotein, corresponding to one difference in the nucleotide sequence of the SLC4A1 gene. Dib is common or ubiquitous in all populations which have been screened for it, while Dia has been found only in Indigenous peoples of the Americas (in both North and South America) and East Asians, and in people with some ancestors from those groups. People heterozygous for the two alleles produce both antigens. No individual has been tested who does not produce one, or both, of the two antigens.[1] Anti-Dia (the antibody to Dia) can cause severe hemolytic disease of the newborn and severe transfusion reaction. Anti-Dib usually causes milder reactions.[2] The Wright blood system is another pair of types, Wrighta (Wra) and Wrightb (Wrb), also differing by one amino acid on the AE1 glycoprotein and one nucleotide on the SLC4A1 gene. Wra always expresses antigens, but the antibody reaction of Wrb depends on a variation in the structure of glycophorin A, which binds with Wrb.[3] Anti-Wra can also cause severe hemolytic disease of the newborn and severe transfusion reaction. Anti-Wrb is very rare, and little data is available on its severity.[2] Seventeen other rare blood types (as of 2002) are included in the Diego antigen system, as they are produced by mutations on the SLC4A1 gene. These include the Waldner (Wda), Redelberger (Rba), Warrior (WARR), ELO, Wulfsberg (Wu), Bishop (Bpa), Moen (Moa), Hughes (Hua), van Vugt (Vga), Swann (Swa), Bowyer (BOW), NFLD, Nunhart (Jna), KREP, Traversu (Tra), Froese (Fra) and SW1 types.[4]

History Edit

The first Diego antigen, Dia, was discovered in 1953, when a child in Venezuela died of hemolytic disease three days after birth. Rh and ABO blood type mismatches were soon ruled out, and investigators began searching for a rare blood factor. Red blood cells from the father reacted strongly to blood serum from the mother. Rare blood types known at the time were eliminated, and the new type was classified as a "private" or "family" blood type. The investigators, with the agreement of the father, named the new type after his surname, "Diego". In 1955 investigators found that the Diego family included ancestry from Indigenous peoples of the Americas, and that the Diego factor (Dia) was not restricted to the Diego family, but occurred in several populations in Venezuela and elsewhere in South America. Investigators suspected that the Diego factor might be a Mongoloid trait, and tested groups of Native Americans in the United States and people of Chinese and Japanese ancestry, and found Dia in those groups. Anti-Dib was found in 1967, establishing the Diego group as a two-antigen system. In 1993 the Diego pair of antigens was found to result from a single point mutation (nucleotide 2561) on what is now called the SLC4A1 gene on chromosome 17.[1] The Wrighta antigen (Wra), a very low frequency blood type, was also discovered in 1953. The Wrightb antigen (Wrb), a very high frequency blood type, was discovered about a decade later, but the two types were not recognized as a pair for another 20 years. The Wright group was eventually identified as a single point mutation on the SLC4A1 gene. The Wright group was subsumed into the Diego group in 1995, since its location on the SLC4A1 gene had been determined after the Diego group had been located there.[2] Starting in 1995, various rare antigen types, some of which had been known for 30 years, were found to also be caused by mutations on the SLC4A1 gene, and were therefore added to the Diego system.[2]

Distribution of the Diegoa antigen Edit

Data tables Edit

Frequency of the Diego Factor in Mongoloids Study Total

number

tested Dia+ No. % Korean by Lee, Present series 117 17| style="text-align:center;"|14.5 Chinese by Layrisse and Arends, (1956) 100 5 5.0 Japanese by Layrisse and Arends, (1956) 65 8 12.31 Japanese by Lewis et al., (1956) 77 6 7.79 Japanese by Ueno and Murakata, (1957) 153 12 7.84 Japanese by Lewis et al., (1958) 145 10 6.89 Japanese by Iseki et al., (1958) 500 16 3.20 Source: Table 12, Page 23, Samuel Y. Lee (1965)[13]