Galactosaemia Deficiency: GALT Sequencing

Diagnostic Use

Galactosemia is an autosomal recessive toxicity syndrome associated with the administration of galactose to patients with an inherited disorder of galactose utilization. It arises from a deficiency in one of three enzymes: galactokinase, galactose uridyl-transferase (GALT) or UDP-4-epimerase. By far the most common of these is GALT deficiency, with an incidence of 1/40 000 in Caucasians. GALT deficiency results in acute neonatal toxicity in affected individuals who are given lactose. The inability to process galactose-1-P leads to early accumulation of galactose and galactose-1-P, with longer-term build-up of galactitol and galactonate. Although the pathogenic pathway is not clear, clinical effects are seen both in infancy and later in life. After a few days of lactose consumption, an affected neonate often develops vomiting, diarrhoea, lethargy and hypotonia. Over the following weeks to months, jaundice (due to hepatic damage and haemolysis), cataracts, failure to thrive and developmental delay may become evident. Neonates and infants with galactosemia are also prone to E.coli sepsis. Longer-term adverse effects include CNS disturbances, decreased puberty growth spurt, and ovarian atrophy in females. Withholding lactose from the neonatal diet can prevent the ‘acute’ manifestations of galactosemia in infancy, although many of the long term affects can’t be avoided.


Genetics - Molecular Pathology

Delphic Registration Code


Constituent Tests


GALT deficiency

Turnaround Time

4 weeks

Test Code