G6PD gene
Also known as G6PD deficiency.
OMIM#300908 https://omim.org/entry/300908
1. The disease:
Glucose-6-phosphate dehydrogenase deficiency (G6PD) is a hereditary abnormality involving the activity of a red blood cell enzyme. This enzyme, glucose-6-phosphate dehydrogenase, is essential for assuring a normal life span for red blood cells, and for oxidizing processes. A deficiency in this enzyme may provoke the sudden destruction of red blood cells and lead to haemolytic anaemia with jaundice following the intake of fava beans, certain legumes, and various medications. Many individuals with G6PD deficiency, however, are asymptomatic. G6PD is inherited as an X-linked defect. Males with a G6PD deficiency mutation on their X chromosome are affected. Females with one G6PD deficiency mutation are carriers at a 50% risk to pass their G6PD deficiency X chromosome to a male child. As an X-linked disorder, G6PD deficiency would generally be thought to affect only males. However, females having a G6PD deficiency mutation on both of their X chromosomes also have clinical symptoms. G6PD deficiency confers partial protection against malaria, which probably accounts for the persistence and high frequency of mutations in the G6PD gene.
2. The symptoms:
Most babies with G6PD deficiency are asymptomatic at birth. The lack of early signs or symptoms does not exclude the diagnosis.
- Infants can remain asymptomatic or may develop neonatal jaundice and haemolysis serious enough to cause neurologic damage or even death.
- Aside from the aforementioned rare, severe complications in the newborn period, babies with G6PD deficiency typically experience normal growth and development.
- Exposure to certain antimalarial drugs and sulfonamides, infection stress (such as upper respiratory infection or GI infections), environmental agents (e.g. mothballs), and certain foods (e.g. fava beans), each of which can have an effect of the body’s ability to handle oxidative reactions, can cause acute haemolytic anaemia.
- There are variable expression of symptoms and people may be asymptomatic throughout life.
3. Actions to take in case of early diagnosis:
- Infants with a positive genetic test should have confirmatory testing using a quantitative assay to measure the amount of enzyme activity.
- Babies with G6PD deficiency may be at increased risk for pathological newborn jaundice and should be closely monitored for associated complications during the newborn period.
- Excluding the recommended monitoring for potential complications in the newborn period, treatment for G6PD deficiency is avoidance.
- In the baby, this means avoidance of several medications routinely prescribed for infections and illness.
- Strict attention to the ingredients of prepared foods and restaurant meals is required as fava beans are a frequent addition to prepared foodstuffs.
- Patients should not be exposed to mothballs containing naphthalene.
- The adverse effects of infection on patients with G6PD deficiency can be acute and life threatening.
- Over exertions from exercise and work leading to dehydration and hypoglycemia can precipitate clinical symptoms.
- Patients that avoid above limitations can lead a normal life.
- All siblings of babies diagnosed with G6PD deficiency should be tested; genetic counseling services should be offered to the family.
4. For more information:
Biblio : Harcke SJ, Rizzolo D, Harcke HT. G6PD deficiency: An update. JAAPA. 2019;32(11):21-26. PMID: 31609781