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Table 1 G6PDd variant types

From: Spatial distribution of G6PD deficiency variants across malaria-endemic regions

Type

Residual enzyme activity

Population-level prevalence

Clinical significance

Primaquine-associated public health concern

Type 1

<10%

Sporadic (never polymorphic)

Severe and chronic: CNSHA

None – too rare

Type 2§

<1-50%

Polymorphic

Asymptomatic until exposed to an exogenous trigger

Yes – commonly inherited and cause individuals to be at risk of haemolysis

Type 3

Normal (>50%)

Polymorphic (wild-type)

None

None – G6PD normal

  1. §Type 2 variants have previously been separated into Class II and Class III variants of the WHO-endorsed G6PDd variant classification[28, 29]. For many variants, however, this subdivision is blurred and poorly defined[25].