Year: 1985
Type: article
Study design: Observational Study
Abstract: The percentage of G gamma chains in the Hb F of SS patients and beta-thalassemia heterozygotes is generally 40%, but some have 60% to 70% G gamma. To test the hypothesis that DNA sequence variation 158 base pairs 5' of the G gamma gene is associated with this variation in G gamma values, DNA was analyzed using the restriction endonuclease Xmn I (gamma IVS-II probe). Xmn I recognizes the sequence from -157 to -166 only if T is at position -158. Individuals from five families had T at -158 for G gamma genes in both chromosomes, and the mean G gamma value was 69.7% +/- 4.6% (SD). For 13 families, individuals with T at -158 for the G gamma gene of one chromosome had a G gamma value of 60.6% +/- 5.7%. With one exception, lack of T at -158 was associated with low G gamma values (39.6% +/- 4.0%). In low Hb F G gamma-beta+-HPFH, the Xmn I site was seen 5' to both G gamma and A gamma genes, which suggests that T at -158 is associated with elevated Hb F; Pst I digestion showed that the A gamma gene T producer G gamma globin, which accounts for high levels of G gamma (87-88%). Calculations show that T at -158 is associated with a three- to 11-fold increase in production per G gamma gene, which is an order of magnitude less than that associated with the previously identified -202 C----G substitution of high Hb F G gamma-beta+-HPFH.
Source: Blood
Authors: JG Gilman, TH Huisman
Institution: Augusta University
Language: English
Subfield: Genetics (clinical)
Field: Medicine
Domain: Health Sciences
Open Access status: bronze
Awards: G1597995125, G1646607883
OpenAlex ID: W58134837