Detection of Hpdel among Thais, a deleted allele of the haptoglobin gene that causes congenital haptoglobin deficiency.
BACKGROUND
Congenital haptoglobin deficiency is a risk factor for anaphylactic nonhemolytic transfusion reactions in Japan. The deleted allele of the haptoglobin gene, Hp(del), which causes congenital haptoglobin deficiency, has also been observed in other Northeast Asian populations, such as Korean and Chinese persons. It has not been reported in several African and European-African populations, however, or investigated in other countries.


METHODS
To investigate the distribution of congenital haptoglobin deficiency in Southeast Asian countries, blood samples collected from 200 randomly selected healthy Thai volunteers were analyzed for serum haptoglobin and the haptoglobin gene. Plasma haptoglobin concentration was measured to identify haptoglobin deficiency. Haptoglobin phenotyping was performed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by Western blotting. The presence of the Hp(del) allele was determined with genomic DNA by an Hp(del)-specific polymerase chain reaction (PCR) method.


RESULTS
There were no haptoglobin-deficient subjects detected among the 200 Thais. Their haptoglobin phenotypes were as follows: Hp 1-1 in 10, Hp 2-1 in 81, and Hp 2-2 in 109. Six individuals heterozygous for Hp(del) were detected. The frequency of the Hp(del) allele was calculated to be 0.015. The prevalence of haptoglobin deficiency caused by Hp(del) homozygosity was estimated to be approximately 1 in 4000.


CONCLUSIONS
Congenital haptoglobin deficiency caused by Hp(del) homozygosity is presumed to be present in Thailand as a risk factor for anaphylactic transfusion reactions with a frequency similar to that in Japan. The causative deleted allele of the haptoglobin gene, Hp(del), is distributed among Southeast Asian populations as well as among Northeast Asian populations.
Shimada
Eiko
E
Research and Development Department, Central Blood Institute, Blood Service Headquarters, Japanese Red Cross Society, Tokyo, Japan. shimada@bs.jrc.or.jp
Odagiri
Miki
M
Chaiwong
Kriangsak
K
Watanabe
Yoshihisa
Y
Anazawa
Masako
M
Mazda
Toshio
T
Okazaki
Hitoshi
H
Juji
Takeo
T
O'Charoen
Rachanee
R
Tadokoro
Kenji
K
D000483:Alleles; D044466:Asian People; D004797:Enzyme-Linked Immunosorbent Assay; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000208:ethnology / Q000235:genetics*; D006242:Haptoglobins / Q000172:deficiency* / Q000235:genetics*; D006720:Homozygote; D006801:Humans; D007564:Japan; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D013785:Thailand
C485359:HP protein, human; D006242:Haptoglobins