Triosephosphate isomerase deficiency: 2 new cases.

Area of Science:

• Biochemistry
• Genetics
• Hematology

Background:

• Triosephosphate isomerase (TPI) deficiency is a rare inherited metabolic disorder.
• It is characterized by severe hemolytic anemia and neurological abnormalities.
• This study investigates TPI deficiency in two Italian families.

Observation:

• Two new cases of TPI deficiency were identified in unrelated Italian families.
• The deficiency was present in erythrocytes, leukocytes, platelets, and plasma.
• One case underwent extensive investigation of the TPI enzyme.

Findings:

• The mutant TPI enzyme exhibited altered kinetic properties, including a normal Km for glyceraldehyde-3-phosphate (GAP) and an increased Km for dihydroxyacetone phosphate (DHAP).
• The enzyme also showed a higher than normal equilibrium constant, decreased thermostability, and an abnormal electrophoretic pattern.
• Immunological characterization indicated reduced inactivation by specific antiserum, though standard immunodiffusion patterns were normal. Lymphocyte, granulocyte, and platelet functions were impaired.

Implications:

• These findings contribute to understanding the molecular basis of TPI deficiency.
• The study highlights the enzyme's dysfunction and its impact on cellular functions.
• Further research may elucidate TPI's role in hemolytic anemia and immune cell function.