Identification and key management of non-transfusion-dependent thalassaemia patients: not a rare but potentially under-recognised condition

Table 1 Genotypes and phenotypes of thalassaemia

	VariantVariant	GenotypeGenotype	Phenotype
β-thalassaemia	Normal	αα/αα	Normal
	Silent Carrier	-α/αα	Haematologically silent or mild reduction of MCH/MCV
	Minor	-α/-α , - -/αα	Borderline anaemia or normal, as well as microcytic and hypochromic red blood cells
	HbH disease*	- -/-α , - -/αTα, αTα/αTα ^T - -/- - ^T α ^T α	Majority have mild to moderate anaemia and marked microcytosis and hypochromia, only few have phenotype similar to thalassaemia major
	Barts Hydrops Foetalis	- -/- -	Most develop hydrops foetalis syndrome and die in utero, or shortly after birth
β-thalassaemia	Normal	β/β	Normal
	Minor	β/β+⁺ , β/β0⁰	Borderline anaemia or normal as well as microcytic and hypochromic red blood cells
	β-thalassaemia intermedia*	β ⁺ /β ⁺ ,β ⁰ /β ⁺ , β ⁺ /β, β ⁰ /β, β ⁰ /β ⁰	Severity is very variable. Clinical picture ranges from mild to moderate NTDT
	Major	β⁰β⁰ , β⁰/β⁺	Severe anaemia requiring regular transfusions (TDT)
HbE	HbE trait	β^E/β	Asymptomatic condition with no clinical relevance
	Homozygous HbE	β^E/β^E	Usually asymptomatic with borderline asymptomatic anaemia and no haemolysis
	HbE/ β-thalassaemia*	β ^E /β ⁺ ,β ^E /β ⁰	Severity is very variable. Clinical picture ranges from NTDT to TDT
	HbE/HbS	β^E/β^S	Similar to sickle cell disease usually with rare vaso-occlusive crisis

ISSN: 1750-1172