Abbreviations and glossary

α

the Greek letter alpha

α chain

the α globin chain, which is required for synthesis of haemoglobins A, F and A2 and also the embryonic haemoglobin, Gower 2

α gene

one of a pair of genes on chromosome 16, HBA1 and HBA2, that encode α globin

α thalassaemia

a group of thalassaemias characterised by absent or reduced α globin chain synthesis, usually resulting from deletion of one or more of the α globin genes; less often it results from altered structure of an α gene or mutation of the locus control gene, LCRA, or genes encoding trans‐acting factors

α0 thalassaemia

a thalassaemic condition in which there is no α globin chain translation from one or both copies of chromosome 16

α+ thalassaemia

a thalassaemic condition in which there is reduced but not absent translation of α globin chain from one or both copies of chromosome 16

β

the Greek letter beta

β chain

the β globin chain, which forms part of haemoglobin A and haemoglobin Portland 2 and is the only globin chain in the abnormal haemoglobin, haemoglobin H

β gene

the gene on chromosome 11, HBB, that encodes β globin

β thalassaemia

a thalassaemia characterised by reduced β globin synthesis, usually caused by mutation of a β globin gene; less often it results from gene deletion or from deletion or mutation of the locus control region, LCRB

β thalassaemia intermedia

a β thalassaemia with significant clinicopathological abnormalities but not dependent on transfusion for survival; also known as non‐transfusion‐dependent thalassaemia

β thalassaemia major

a β thalassaemia with significant clinicopathological abnormalities, requiring transfusion to sustain life

γ

the Greek letter gamma

γ chain

the γ globin chain which forms part of fetal haemoglobin (haemoglobin F) and the embryonic haemoglobin, haemoglobin Portland 1, and is the only globin chain in the abnormal variant, haemoglobin Bart's

γ gene

one of a pair of very similar genes on chromosome 11, HBG1 and HBG2, encoding γ globin chain

γ thalassaemia

a thalassaemic condition resulting from reduced synthesis of γ globin chain

δ

the Greek letter delta

δ chain

a β‐like globin chain, which forms part of haemoglobin A2

δ gene

a gene of the β cluster on chromosome 11, HBD, that encodes δ globin

δ thalassaemia

reduced or absent synthesis of δ globin and therefore of haemoglobin A2

ε

the Greek letter epsilon

ε chain

the ε globin chain, which is synthesised during early embryonic life and forms part of haemoglobins Gower 1 and Gower 2

ε gene

a gene of the α globin cluster on chromosome 16, HBE1, that encodes ε globin chain

ψ

the Greek letter psi, used to indicate a pseudogene

ζ

the Greek letter zeta

ζ chain

the ζ globin chain that is synthesised in intrauterine life and that forms part of haemoglobins Gower 1, Portland 1 and Portland 2

ζ gene

a gene of the α globin gene cluster on chromosome 16, HBZ, that encodes ζ globin chain

2,3 DPG

2,3‐diphosphoglycerate; a small molecule that interacts with haemoglobin, decreasing its oxygen affinity

3′

the end of a gene where transcription ceases

5′

the end of a gene where transcription starts

acquired

a condition that is not present at birth or is not inherited

affinity

the avidity of haemoglobin for oxygen

AHSP

α haemoglobin stabilising protein (AHSP)

AIDS

acquired immune deficiency syndrome

ala

δ‐aminolaevulinic acid, the first compound formed during the process of haem synthesis

AML

acute myeloid leukaemia

ARMS

amplification refractory mutation system, a PCR technique used, for example, for the detection of mutations causing β thalassaemia; it employs two primer sets, one amplifying normal sequences and one abnormal sequences

balanced polymorphism

the stable persistence of two or more alleles of gene in a significant proportion of a population; a potentially deleterious allele may show balanced polymorphism if the heterozygous state conveys an advantage

base

a ring‐shaped organic molecule containing nitrogen, which is a constituent of DNA and RNA; DNA contains four bases: adenine, guanine, cytosine and thymine; RNA contains four bases: adenine, guanine, cytosine and uracil

Bohr effect

the effect of pH on oxygen affinity; the alkaline Bohr effect is the reduction of oxygen affinity of haemoglobin as pH falls from above to below the physiological pH; there is also an acid Bohr effect which is a rise of oxygen affinity as the pH falls further, at a pH level that is incompatible with life

bp

base pair, the pairing of specific bases, e.g. adenine with thymine, in the complementary strands of the DNA double helix

CAP

7‐methyl guanosine cap, added to RNA molecule during processing

capillary electrophoresis

electrophoresis within a capillary tube

carbonic anhydrase

a red cell enzyme that is the second most abundant red cell protein after haemoglobin; it may be apparent on haemoglobin electrophoretic strips if a protein rather than a haem stain is used

carboxyhaemoglobin

haemoglobin that has been chemically altered by combination with carbon monoxide

CE‐HLPC

cation‐exchange high performance liquid chromatography; see HPLC

chromatography

a method of separating proteins from each other by means of physical characteristics, such as molecular weight, charge or hydrophobicity, or by means of differing affinity for lectins, antibodies or other proteins; in column chromatography the proteins move through an absorbent column and emerge after different periods of time

cis

on the same chromosome (see also trans)

cis‐acting

a DNA sequence that affects the expression of a gene on the same chromosome but not on the homologous chromosome (see also trans‐acting)

CNV

copy number variant

CO

carbon monoxide, the molecule composed of one carbon atom and one oxygen atom, formed by combustion of hydrocarbons

CO2

carbon dioxide, the molecule composed of one atom of carbon combined with two atoms of oxygen

codon

a triplet of nucleotides that encodes a specific amino acid or serves as a termination signal; there are 61 codons encoding 20 amino acids and three codons that act as termination or STOP codons

congenital

present at birth, often but not necessarily inherited

cooperativity

the interaction between the four globin monomers that makes possible the Bohr effect and the sigmoid shape of the oxygen dissociation curve

COVID‐19

corona virus disease 2019

CT

computed tomography

CV

coefficient of variation

DCIP test

a screening test for haemoglobin E using dichlorophenolindophenol

deletion

loss of part of a chromosome, which may include all or part of a globin gene

deoxyhaemoglobin

haemoglobin that is not combined with O2

DGGE

denaturing gradient gel electrophoresis, a molecular genetic technique for locating a mutation prior to precise analysis

DNA

deoxyribonucleic acid, the major constituent of the nucleus of a cell; a polynucleotide strand that is able to replicate and that codes for the majority of proteins synthesised by the cell; the DNA molecule is a double helix of two complementary intertwined polynucleotides

EDTA

ethylene diamine tetra‐acetic acid

eIF2

erythroid initiation factor 2

EKLF

erythroid Krüppel‐like factor

electrophoresis

separation of charged suspended particles such as proteins by application to a membrane or gel or within a capillary followed by exposure to a charge gradient, e.g. haemoglobin electrophoresis

ELISA

enzyme‐linked immunosorbent assay

elution

removal of an absorbed substance from a chromatography column or membrane

enhancer

a DNA sequence that influences the promoter of a nearby gene to increase transcription; an enhancer acts on a gene in cis and may be sited...