Some Rare Hemoglobin Variants with Altered Oxygen Affinities; Hb Linkoping [β36(C2)Pro→Thr], Hb Caribbean [β91(F7)Leu→Ar6], and Hb Sunnybrook [β 36(C2)Pro→Arg]

Abstract

A few rare hemoglobin variants with altered functional properties have been observed in Canadian subjects with either an erythrocytosis or mild anemia. These variants were Hb Alberta [beta 101(G3)Glu----Gly], Hb Linkoping [beta 36(C2)Pro----Thr], a new variant Hb Sunnybrook [beta 36(C2)Pro----Arg], and Hb Caribbean [beta 91(F7)Leu----Arg]. Short clinical descriptions of the subjects are given, the characterization of the variants is described in detail (except for Hb Alberta), while data from some functional analyses are provided. Comparisons with previously published data have been made and the unusual chromatographic property of two abnormal beta chains in a reversed phase high performance liquid chromatographic system is reviewed.

“The Long Journey of Unexplained Erythrocytosis”: Erythrocytosis due to High-Oxygen Affinity Hemoglobinopathy – Hemoglobin Variant Little Rock (HBB: c.432C>A) – A Report of a Swiss Family and Review of the Literature

“…However, symptoms associated with hyperviscosity such as headaches, vertigo, tinnitus, and paresthesia in the extremities can occur. The laboratory and clinical findings of the three affected members of the presented family are similar to other reported cases of highoxygen affinity hemoglobinopathy (Hb Linköping, Hb Saint Nazaire) [15,16]. If patients are symptomatic, a trial of therapeutic phlebotomy is possible with subsequent reassessment of the symptoms.…”

Compound Heterozygosity for a Mild β⁺ and a Rare β°-Thalassemia Allele

“…A compar ison of the data for patients 11-2 and 11-3 with those for patients 11-10 and 556 indicates that the presence of the a-thalassemia-2 heterozygosity does not mod ify these values. The synthesis of the pA chain is regu lated by the chromosome with the -2 9 (A -G) muta tion; the average value of 18.5% observed for our patients is comparable to the values observed in pa tients with either a homozygosity for this mutation [12] ora heterozygosity in combination with Hb S [17]. The Gy value in the Hb F of all 5 subjects was high (average 69.8%); this likely suggests that the synthesis of the Gy and ay chains in these patients is primarily regulated by the chromosome with the -29 (A -G) mutation.…”

“…Identification of the (5-thalassemia mutations was by dot-blot analysis of amplified DNA with 32P-labelled synthetic oligonucleotides; this procedure has been de scribed in detail before [11,12].…”

Application of CRISPR-Cas12a technology in zebrafish to simulate ß-globin gene (HBB) mutations

“…The gRNA (Sigma-Aldrich) design (Table S9) requires a 20 bp complementary sequence to the non-target strand of the gene of interest; A 3’-uridylated (U8-) tail for increased INDEL efficiency (Bin Moon et al 2018) 30 , and a generic region (5’-UAGGUAAUUUCUACUAAGUGUAGAU–N20–UUUUUUUUU-3’) for the Cas12a protein (S2 Fig). The target site was aligned with the human adult hemoglobin HBB gene with a similar mutation CTG>CGG (Leucine to Arginine) at codon 91 (Fig 1) reported by Ali et al, (1988) in Canadian ethnicity [36].…”

“…The gRNA (Sigma-Aldrich) design (Table S9) requires a 20 bp complementary sequence to the non-target strand of the gene of interest; A in Canadian ethnicity [36]. The repair template hbbe1.1-L33P to induce the L33P mutation in hbbe1.1 at codon 33 inside the zebrafish genome and the gRNA for Cpf1-L33P are given in Table S1.…”