Haplotypes in SS patients from Nigeria; characterization of one atypical βS haplotype no. 19 (Benin) associated with elevated HB F and highGγ levels

Autor: Titus H.J. Huisman, L.-H. Gu, M. N. Kitundu, Adekunle Adekile, K. D. Lanclos, O. O. Adeodu
Rok vydání: 1992
Předmět:
Zdroj: Annals of Hematology. 65:41-45
ISSN: 1432-0584
0939-5555
DOI: 10.1007/bf01715125
Popis: We have determined the haplotypes of 669 beta S and 109 beta A chromosomes from numerous members of 297 Nigerian families of various ethnic backgrounds. Among the beta S chromosomes, haplotype 19 was detected in 93.2%, haplotype 17 in 3.4%, and haplotype 20 in 0.1%, while 2.4% represented atypical haplotypes. As many as 60.6% of the beta A chromosomes exhibited haplotype 19 mutations, 8.2% had haplotype 3, and 1.8% had haplotype 20. Two siblings with elevated Hb F and G gamma levels were heterozygous for a beta S chromosome with haplotype 19 and a second chromosome with a hybrid haplotype (termed 19 B). In this hybrid chromosome, haplotype 3-like locus control region (LCR) [hypersensitive site-2 (HS-2)] sequences are in juxtaposition to those of the 5' flanking region of the G gamma promoter of a beta S chromosome with haplotype 19. The presence of this hybrid chromosome is associated with high G gamma values in individuals with both sickle cell anemia (SS) and sickle cell trait (AS); it closely resembles another hybrid beta S chromosome, termed 19 A, observed in a previously reported Turkish SS patient who was homozygous for this chromosome and had high Hb F and high G gamma values. In both instances, it is hypothesized that the haplotype 3-like sequences of the LCR HS-2 contain genetic determinants that can combine with factors produced during hematopoietic stress, resulting in increased gamma-globin gene expression.
Databáze: OpenAIRE
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