Different forms of XXXX in the Chinese.

@entity7723 @entity1 @entity417 @entity3458 @entity381 @entity367
A marked genetic and clinical variability of the Hb H syndrome occurs because of the molecular heterogeneity of @entity7723 ( @entity7723 ). The hallmark is the presence of excess beta chains forming Hb H (beta tetramer). In the Chinese, classical @entity3458 presents as " @entity7723 intermedia" and is due to a double heterozygosity for two deletional forms of alpha- @entity7723 , alpha- @entity7723 -1 and alpha- @entity7723 -2. The majority of cases with an alpha- @entity7723 -1 defect have a deletion of at least 18.1 kb starting 3' to the zeta 1 gene which includes the psi alpha and the two alpha genes; it is similar to that described in Thais. However, two families had a deletion of the entire zeta-alpha gene cluster, i.e. zeta-alpha- @entity7723 -1. Of 33 alpha- @entity7723 -2 defects studied, 26 were the rightward deletion (alpha -3.7 kb, all type I defects) and seven the leftward deletion (alpha -4.2 kb); one of the latter was associated with Hb Q. About 10% of the alpha- @entity7723 defects belong to the nondeletion type, the most common form being Hb Constant Spring (CS). This anomaly, when coinherited with alpha- @entity7723 -1, produces Hb H-CS disease which has a most marked @entity417 and @entity381 due to the instability of the alpha-CS chain. Hb Quong Sze produces an alpha- @entity7723 -2 because of the unstable alpha-Quong Sze chain. One @entity1 who inherited classical @entity3458 and Hb New York (NY) [alpha 113(G15)Val---- @entity367 ] had severe @entity417 , and required frequent blood transfusions due to the deleterious effect of an increased alpha-NY chain turnover.(ABSTRACT TRUNCATED AT 250 WORDS)
