Fructose 1,6-bisphosphatase deficiency is a disorder characterized by deficiency of fructose 1,6-bisphophatase (FDPase) activity, a key enzyme in gluconeogenesis. Gluconeogenesis is a process by which endogenous glucose is produced from non-carbohydrate sources, including gluconeogenic amino acids, glycerol, or lactate. This is a key activity in maintaining glucose homeostasis in the body. FDPase deficiency is a rare disorder, affecting 1 in 20,000 newborns worldwide. Patients with FDPase deficiency show typical signs and symptoms of hypoglycemia and metabolic acidosis following fructose ingestion or infections in the neonatal period. These signs and symptoms include hunger, irritability, light-headedness, fatigue, lethargy, seizures, loss of consciousness, trembling, and even tachycardia, and hypertension.

Fructose 1,6-bisphosphatase deficiency is associated with mutations in the FBP1 gene, which encodes FDPase enzyme.