Glucose-6-phosphate dehydrogenase (G6PD) deficiency in neonates

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Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a genetic disorder which causes haemolysis (premature breakdown of red blood cells).

Key points about G6PD enzyme

Key points about the G6PD enzyme:

• It is a cytoplasmic enzyme in the hexose monophosphate pathway responsible for the production of glutathione. It helps to protect the red blood cell from oxidative damage.
• The G6PD gene lies on the X chromosome and over 300 mutations have been described.
• G6PD deficiency is a common X-linked recessive genetic disorder
• It affects:
  • 1:50 southeast Asians
  • 1:10 Mediterranean families (Italian, Greek and Middle Eastern)
  • 1:10 African- American males
• Because of the high gene frequency in some regions, homozygous affected females are not uncommon.
• Females may also be affected through lyonisation or if they have Turner’s syndrome.

Clinical disorders related to G6PD

There are three major clinical disorders caused by G6PD deficiency :

• neonatal hyperbilirubinaemia
• chronic haemolytic anaemia
• induced haemolytic anaemia triggered by exposure to:
  • naphthalene (mothballs)
  • sulphonamides 
  • nitrofurans 
  • aspirin 
  • fava (broad) beans
  • viral infections.

Symptoms of G6PD deficiency

Symptoms may include:

• dark coloured urine
• splenomegaly
• fatigue
• pallor
• tachycardia
• shortness of breath.

However, neonates usually present with jaundice in the absence of anaemia.

Jaundice can be severe and result in kernicterus.

Differential diagnosis of G6PD deficiency

Causes of haemolytic anaemia

Haemolytic anaemia may be caused by:

• maternal-fetal blood group incompatibilities:
  • rhesus isoimmunisation
  • ABO incompatibility
• other red cell enzyme deficiencies (such as pyruvate kinase)
• red cell membrane disorders (such as hereditary spherocytosis).
• disorders of haemoglobin synthesis (such as alpha thalassaemia group of disorders).

G6PD deficiency should be considered in infants with history of jaundice, anaemia and splenomegaly, especially in those of African or Mediterranean ancestry.