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Test ID: G6PDB Glucose-6-Phosphate Dehydrogenase (G6PD) Full Gene Sequencing, Varies

Useful For

Genetic test for individuals at high risk for glucose-6-phosphate dehydrogenase (G6PD) deficiency


Aiding in the diagnosis of G6PD deficiency


Determining G6PD deficiency status in individuals with inconclusive or unexpected phenotyping results


Differentiation of heterozygous females with skewed X-inactivation from homozygous and compound heterozygous females


Definitive diagnosis of carrier status in females


Evaluation of neonates (particularly males) with unexplained jaundice


Identifying individuals at risk of drug-induced acute hemolytic anemia (AHA) related to G6PD deficiency

Method Name

Polymerase Chain Reaction (PCR) followed by DNA Sequence Analysis

Reporting Name

G6PD Full Gene Sequencing

Specimen Type


Ordering Guidance

For initial or time-sensitive screening for glucose-6-phosphate dehydrogenase deficiency, order G6PD1 / Glucose 6-Phosphate Dehydrogenase Enzyme Activity, Blood.

Necessary Information

1. Patient's sex is required.

2. Include physician name and phone number with the specimen.

Specimen Required

Submit only 1 of the following specimens:


Specimen Type: Whole blood


Preferred: Lavender top (EDTA) or yellow top (ACD)

Specimen Volume: 3 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send specimen in original tube.

Specimen Stability Information: Ambient (preferred) 9 days/Refrigerated 30 days


Specimen Type: Saliva

Patient Preparation: Patient should not eat, drink, smoke, or chew gum 30 minutes prior to collection.

Supplies: Saliva Swab Collection Kit (T786)

Specimen Volume: 1 swab

Collection Instructions: Collect and send specimen per kit instructions.

Specimen Stability Information: Ambient 30 days


Specimen Type: Extracted DNA

Container/Tube: 2 mL screw top tube

Specimen Volume: 100 mcL (microliters)

Collection Instructions:

1. The preferred volume is 100 mcL at a concentration of 250 ng/mcL.

2. Include concentration and volume on tube.

Specimen Stability Information: Frozen (preferred)/Ambient/Refrigerated

Specimen Minimum Volume

Blood: 0.45 mL
Saliva: 1 swab

Specimen Stability Information

Specimen Type Temperature Time Special Container
Varies Varies

Clinical Information

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common human enzymopathy with about 400 million people affected worldwide. It is most commonly found in populations where Plasmodium falciparum malaria is (or was) endemic, but G6PD deficiency may be present in any population.


G6PD converts glucose-6-phosphate to 6-phosphoglyconolactone in the first step of the pentose phosphate pathway (PPP), this reaction also produces nicotinamide adenine dinucleotide phosphate-oxidase (NADPH) from nicotinamide adenine dinucleotide phosphate (NADP). NADPH, through subsequent enzymatic reactions, protects erythrocytes from damage by detoxifying hydrogen peroxide and other sources of oxidative stress.


G6PD is encoded by the gene G6PD, which lies on the X-chromosome. G6PD deficiency is inherited in an X-linked recessive manner; therefore, males are more commonly affected than females, but due to the high prevalence of G6PD deficiency, homozygous and compound heterozygous females are not uncommon. A large number of G6PD pathogenic variants have been discovered. These variants are subdivided into a class system based on definitions from the World Health Organization (WHO).


 Table 1. G6PD variant WHO class and associated G6PD deficiency phenotype

WHO class

Associated Clinical Presentation

G6PD activity


Chronic nonspherocytic hemolytic anemia (CNSHA)



Asymptomatic unless challenged



Asymptomatic unless challenged






With the exception of those with chronic nonspherocytic hemolytic anemia (CNSHA), individuals with G6PD deficiency are typically asymptomatic until they are challenged with an exogenous factor such as a drug, infection, or fava beans. The exogenous factor can trigger acute hemolytic anemia (AHA) in individuals with G6PD deficiency. The severity of AHA is highly variable, ranging from mild to life-threatening and can be fatal. Therefore, determining the G6PD deficiency status is recommended on the Food and Drug Administration label of several drugs either proven or suspected to cause AHA in patients with G6PD deficiency. For a list of drugs known to cause AHA in individuals with G6PD deficiency, see Pharmacogenomic Associations Tables in Special Instructions.


Preemptive genotyping allows for the identification of patients at risk for an adverse reaction to drugs known to cause AHA in those with G6PD deficiency. In most cases, genotyping provides sufficient information to avoid the use of contraindicated drugs. In some cases, including heterozygous females, the phenotyping assay is necessary to determine if such drugs should be avoided. Skewed X-inactivation in heterozygous females has been reported to result in G6PD deficiency, but the phenotyping assay is necessary to determine G6PD activity level. For more information regarding the need for G6PD enzyme activity follow-up testing to this genotyping assay, refer to the G6PD Genotyping Algorithm for Therapeutic Drug Recommendations in Special Instructions.

Reference Values

An interpretive report will be provided.


All detected alterations will be evaluated according to the latest American College of Medical Genetics and Genomics recommendations.(1) Variants will be classified based on known, predicted, or possible effect on gene pathogenicity and reported with interpretive comments detailing their potential or known significance.

Clinical Reference

1. Richards S, Aziz N, Bale S, et al: Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genet Med. 2015;(17):105-423

2. Cappellini MD, Fiorelli G: Glucose-6-phosphate dehydrogenase deficiency. Lancet. 2008;371:64-67

3. Luzzatto L, Seneca E: G6PD deficiency: a classic example of pharmacogenetics with on-going clinical implications. Br J Haematol. 2014;164:469-480

4. OMIM: 305900 Glucose-6-phosphate dehydrogenase. Johns Hopkins University; 1987. Updated August 5, 2019. Accessed December 4, 2020. Available at

5. Relling MV, McDonagh EM, Chang T, et al: Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines for rasburicase therapy in the context of G6PD deficiency genotype. Clin Pharmacol Ther. 2014 Aug;96(2):169-174

Day(s) Performed

Monday, Wednesday

Report Available

3 to 7 days

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
G6PDB G6PD Full Gene Sequencing 94231-8


Result ID Test Result Name Result LOINC Value
37847 Phenotype 47998-0
48399 Result Details 82939-0
37848 Interpretation 69047-9
37850 Method 85069-3
37902 Disclaimer 62364-5
38194 Additional Information 48767-8
37851 Reviewed By 18771-6


1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available in Special Instructions:

-Informed Consent for Genetic Testing (T576)

-Informed Consent for Genetic Testing (Spanish)  (T826)

2. If not ordering electronically, complete, print, and send 1 of the following forms with the specimen:

-Benign Hematology Test Request (T755)

-Therapeutics Test Request (T831)

Mayo Clinic Laboratories | Genetics and Pharmacogenomics Catalog Additional Information: