Table 2. [Assignment of likely G6PD Phenotype based on Genotype/Diplotype (CPIC 2014)]. - Medical Genetics Summaries

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Table 2.

Assignment of likely G6PD Phenotype based on Genotype/Diplotype (CPIC 2014)

Likely phenotype	Definition	Genotype	Who class for G6PD variants^a	Example of diplotype^b
Normal	Very mild or no enzyme deficiency (less than 60% of normal enzyme levels)	A male who has a non-deficient (class IV) allele	IV	B, Sao Boria
Normal		A female who has 2 non-deficient (class IV) alleles	IV/IV	B/B, B/Sao Boria
Deficient	Less than 10–60% of normal enzyme activity	A male who has a deficient (class II–III) allele	II, III	A–, Orissa, Kalyan-Kerala, Mediterranean, Canton, Chatham
Deficient	Less than 10–60% of normal enzyme activity	A female who has 2 deficient (class II–III variants) alleles	II/II, II/III, III/III	A–/A–, A–/Orissa, Orissa/Kalyan-Kerala, Mediterranean/Mediterranean, Chatham/ Mediterranean, Canton/Viangchan
Deficient with CNSHA	Severe enzyme deficiency (<10% activity) and associated with CNHSA	A male who has a class I allele	I	Bangkok, Villeurbanne
Deficient with CNSHA		A female who has 2 deficient (class I variants) alleles	I/I	Bangkok/Bangkok, Bangkok/Villeurbanne
Variable^c	Normal or deficient enzyme activity^c	A female who has one non-deficient (class IV) and one deficient (class I–III variants) allele	IV/I, IV/II, IV/III	B/A–, B/Mediterranean, B/Bangkok

: CNSHA, chronic nonspherocytic hemolytic anemia
: WHO, World Health Organization
^a: WHO classifications (Ref. 14 and Ref. 17, from (29)). Class I variants are extremely rare; the distinction between class II and III variants is not clear, and the “class V” very high activity variant has been reported in only a single case. Therefore, almost all individuals will have class II, III, or IV alleles. It should be noted that the class of a variant may have been assigned only by the clinical manifestations of an individual in which the variant was subsequently identified.
^b: Due to the large number of G6PD variants, many other diplotypes may be possible besides those given as examples here; see Supplementary Table S1 online for a more comprehensive list of variant alleles with their assigned WHO class (29). For HGVS terms, please see the Nomenclature table below.
^c: Due to X-linked mosaicism, females heterozygous for one non-deficient (class IV) and one deficient (class I–III variants) allele may display a normal or a deficient phenotype. It is therefore difficult to predict the phenotype of these individuals (Supplementary Material online (G6PD heterozygotes)) (29).
: This table is adapted from (29).

From: Pegloticase Therapy and G6PD Genotype

Medical Genetics Summaries [Internet].

Pratt VM, Scott SA, Pirmohamed M, et al., editors.

Bethesda (MD): National Center for Biotechnology Information (US); 2012-.

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