Hb J Baltimore (β 16 (A13) Gly ↣ Asp) in Association with β-Thalassemia in a Sicilian Family

The Biosynthesis of Hemoglobin G San José (β 7 (A4) Glu → Gly)

“…In fact, in vitro biosynthesis studies carried out in Hb G San José/«-thalassemia-1 carriers indicated a ftG/ftx specific activity ratio of 1.40 after short-term incu bation [unpublished data from the family studied in ref. 9], suggesting that the fta chain is synthesized at a higher level than that found in peripheral blood and then posttranslationally removed. On the con trary, in the present non-a-thalassemia car rier (II-2) the ftGlftA specific activity ratio was 1.01 after short-term incubation (5 min), and does not significantly vary after longer incubation (up to 120 min), arguing against a posttranslational control of the Hb G San Jose level in the absence of concomi tant «-thalassemia.…”

“…Although an «-thalassemia-2 trait cannot be completely ruled out in the absence of data about gene mapping and mRNA quantitation, nevertheless, on the grounds of both complete absence of even minimal hematological changes and presence of balanced «/total ft chain syn thesis ratios, a concurrent «-thalassemia, which is known to influence the level of this abnormal hemoglobin [9], seems unlikely to occur in the present Hb G San José carriers. Furthermore, it seems very unlikely that the GAG -< • GGG mutation underlying the Glu -*■ Gly substitution is responsible per se for a slow rate of translation of the abnormal j1 chain mRNA, at least as far as polypeptide chain elongation and release from poly somes are concerned, since the GGG codon (coding for ft 46 Gly) is already present in the ft mRNA and a similar codon substitu tion is responsible for Hb Alberta [5] which represents 44.9% of the total Hb.…”

“…In an earlier re port 2 Sicilian subjects in whom heterozy gosity for Hb G San José occurred with a concurrent «-thalassemia-1 trail were de scribed [9]. This report is concerned with the biosynthetic features of this variant as found in another Sicilian family and with in vitro recombination experiments with /?A, and aA chains isolated in their native form.…”

“…Hemoglobin (Hb) G San José (/?7 (A4) Glu Gly) has been found in a number of heterozygotes of Southern Italian origin (Calabria and Sicily) [9]. In an earlier re port 2 Sicilian subjects in whom heterozy gosity for Hb G San José occurred with a concurrent «-thalassemia-1 trail were de scribed [9].…”