The absence of this enzyme results in classic galactosemia in humans and can be fatal in the newborn period if lactose is not removed from the diet.

[5] GALT catalyzes the second reaction of the Leloir pathway of galactose metabolism through ping pong bi-bi kinetics with a double displacement mechanism.

[13] Symptoms include ovarian failure, developmental coordination disorder (difficulty speaking correctly and consistently),[14] and neurologic deficits.

[13] These two mutations also add new restriction enzyme cut sites, which enable detection by and large-scale population screening with PCR (polymerase chain reaction).

[13] Screening has mostly eliminated neonatal death by G/G galactosemia, but the disease, due to GALT’s role in the biochemical metabolism of ingested galactose (which is toxic when accumulated) to the energetically useful glucose, can certainly be fatal.