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Table 1 Common alpha thalassaemia molecular disorders

From: Non-deletional alpha thalassaemia: a review

Mutations Genotype Type and locations
• Deletion at a single α-globin gene -α or –α 3.7, −α4.2, (α)20.5 etc.
• Absence of α-globin genes on one chromosome --MED I, −-MED II, −-SEA, −-SPAN, −-FIL, −-THAI,
• Mutations that affect the upstream regulatory elements (αα)T (αα)RA, (αα)ALT, (αα)JX
• Non-deletional mutations αTα, ααT or αTαT αCSα, αQSα, αADANAα, α IVS1(−5nt) α
  1. MED I & II: Mediterranean I & II; SEA: South East Asia; FIL: Philippines; SPAN: Spain; THAI: Thailand; CS: Constant Spring; QS: Quong Sze; IVS1: Intervening Sequence; [αα]T: Deletion of the upstream enhancer elements; −α3.7: Single-gene deletion; −α4.2: Single-gene deletion; (α)20.5: Double-gene deletion; −-MED I: Double-gene deletion; −-MED II: Double-gene deletion; −-SPAN: Double-gene deletion; α2 IVS1: 5-bp deletion; ααα anti-3.7: Gene triplication; α1 cd 59: G > A (Hb Adana); −-FIL: Double-gene deletion; −-THAI: Double-gene deletion; −-SEA: Double-gene deletion; α2 cd 125: T > C (Hb Quong Sze); α2 cd 142: T > C (Hb Constant Spring).