Delta globin gene variations leading to reduction in HbA₂ levels

Abstract

In the countries, where β-thalassaemia is prevalent, an awareness and detection of different δ-globin gene mutations is important, as complex interactions between these haemoglobinopathies can lead to the misdiagnosis of β-thalassaemia carriers.

First report of the spectrum of δ‐globin gene mutations among women of reproductive age in Fujian area—Discrimination of δ‐thalassemia, α‐thalassemia, and Iron Deficiency Anemia

“…However, in some situations, normal, borderline, or reduced HbA 2 level may still be associated with β thalassemia trait, which will make difficulty in the setting of genetic counseling, whereas a decreased HbA 2 level may lead to the suspicion of IDA, δ‐thalassemia, and α‐thalassemia. What's more, IDA needs to be confirmed by other biological parameters or by a therapeutic correction trial and δ‐thalassemia, α‐thalassemia needs DNA sequencing or other specific analysis 8‐13 …”

“…Mutations that occur on the beta globin gene generally F I G U R E 1 Sequence results of the 2 known and 3 novel δ-globin gene mutations, A, −77 T > C mutation; B, −30 T > C mutation; C,-44G > A mutation; D,CD87C > T mutation; E,CD134T > A mutation tend to an increased HbA 2 levels, but in some situations, β thalassemia traits are not associated with raised HbA 2 . Furthermore, β thalassemia in combination with δ-thalassemia is described, as well as co-association with α-thalassemia, which are sources of diagnostic pitfalls in carrier screening and counseling [9][10][11][12][13]. To date, 137 δ globin gene mutations have been reported, as summarized in http://globin.cse.psu.edu/hbvar/ menu.html (accessed March 12, 2020).…”

The phenotypic and molecular diversity of hemoglobinopathies in India: A review of 15 years at a referral center

“…Such atypical heterozygotes would be missed in screening programs. Associated δ gene mutations are now increasingly being reported in such heterozygotes leading to lowering of HbA 2 levels . In the UK population, investigating 127 δ alleles in patients with either low HbA 2 levels or a split HbA 2 peak picked up nine δ chain variants and two δ thalassemia mutations which included three novel variants .…”

“…Associated δ gene mutations are now increasingly being reported in such heterozygotes leading to lowering of HbA 2 levels. [38][39][40] In the UK population, investigating 127 δ alleles in patients with either low HbA 2 levels or a split HbA 2 peak picked up nine δ chain variants and two δ thalassemia mutations which included three novel variants. 41 Thus delta genotyping is important particularly in couples where one of the partners is a classical β thalassemia carrier and the other has normal/ borderline HbA 2 levels and they have come for testing during an ongoing pregnancy.…”

A Novel Mutation of the δ-Globin Gene in an Asymptomatic 30-Year-Old Female

“…142000) resulting from mutations on the HBD gene usually has no clinical consequences, but it may cause a reduced rate of hemoglobin A 2 (HbA 2 ) [1,2]. Human HbA 2 (α 2 δ 2 ), which contains δ-globin, represents a minor fraction of the Hb found in human adults.…”