Synergistic effect of two ß globin gene cluster mutations leading to the hereditary persistence of fetal hemoglobin (HPFH) phenotype.

Co-inheritance of gamma and beta globin gene mutations in a compound heterozygous state is rare but of clinical interest as it provides an important data on understanding the HbF expression. Hematological analysis was carried out (Sysmex KX-21). F-cells were enumerated using flow cytometry. Beta globin gene was analysed by CRDB technique and by DNA sequencing. Gamma globin promoter region was sequenced and expression studies were carried out using real time Taqman assay. We report a family, where two inherited defects of the ß globin gene cluster segregate. The proband and her sibling were compound heterozygotes for a novel Gγ promoter mutation and the 619 bp deletion a common Indian ß thalassemia mutation. Molecular characterization revealed that the father (HbA2 5.1%, HbF 5.4%), proband (HbA2 3.6%, HbF 31.7%) and her brother (HbA2 3.9%, HbF 23.6%) were heterozygous for the 619 bp deletion. The mother (HbA2 2.1%, HbF 3.4%) had a normal ß globin gene. As both the children showed high HbF levels, the γ globin gene work up was carried out. The Gγ-globin gene promoter analysis revealed that the mother and the two children were heterozygous for a 5 bp deletion -ATAAG (-533 to -529) that resides in the GATA binding site. These findings suggest that the 5 bp deletion in the Gγ globin promoter has a functional role in silencing the γ-globin gene expression in adults by disrupting GATA-1 binding and the associated repressor complex and results in the up-regulation of gamma globin gene expression. When co-inherited with ß -thalassemia trait it leads to a phenotype of HPFH.

Five Rare ß Globin Chain Hemoglobin Variants in India.

Thalassemias as well as structural hemoglobin (Hb) variants are common monogenic inherited disorders of Hb in India. In this paper we describe 5 rare ß-chain Hb variants identified in the Indian population on the basis of high performance liquid chromatography (HPLC). Of these 3 were identified during antenatal screening of ß-thalassemia while the other 2 cases were referred to us for a diagnostic work up. These 5 Hb variants were Hb British Columbia (ß CD 101 GAG â†’ AAG), Hb Saint Louis (ß CD28 CTG â†’ CAG), Hb G Coushatta (ß CD 22 GAA â†’ GCA), Hb Pyrgos (ß CD 83 GGC â†’ GAC) and Hb Agenogi (ß CD 90 GAG â†’ AAG). Hb Saint Louis and Hb G Coushatta eluted in the HbA2 window, Hb British Columbia and Hb Agenogi eluted in the Hb C window while Hb Pyrgos eluted in an unknown window on HPLC. They were all identified by DNA sequencing. The child having Hb St. Louis had hepatosplenomegaly and anemia while the individuals with the other 4 variants were asymptomatic. Rare Hb variants are diagnostic curiosities that may be encountered by laboratories. Correct identification requires the application of more than one technique to avoid misdiagnosing them as more common variants (e.g. St. Louis and G Coushatta as E or D Iran on HPLC. Some, like G Coushatta may interfere with HPLC-based HbA1c estimation).

Development and characterization of new cell line BPH22 from midgut epithelial cells of Poekilocerus pictus (Fabricius, 1775).

Poekilocerus pictus is a painted grasshopper, which feeds on Calotropis sp. containing the cardiac glycosides. A new cell line BPH22 is developed from midgut of P. pictus to study its unique physiology and biochemistry. Initially, the Graces insect medium is used with 10% (v/v) fetal bovine serum. After four passages, the serum quantity was reduced up to 0%.The lag phase in growth curve was 5 d and log phase is up to 10-11 d. The addition of Calotropis extract in Graces medium enhanced the growth of cells. The Calotropis extract with Graces medium altered the morphology of cells of BPH22. The amplification and sequencing of 16S rRNA gene confirmed the origin and purity of the BPH22.