Research projects

Propionic acidemia (PA, OMIMID: 606054) is a congenital metabolic disorder caused by Propionyl CoA Carboxylase (PCC; EC 6.4.1.3) deficiency, which converts Propionyl CoA (PCoA) into D-Methylmalonyl CoA; its frequency of occurrence is 1/100,000 live births, and it is inherited as recessive and autosomic. The accumulation of PCoA produces several mitochondrial disorders: metabolic acidosis (accumulation of ketonic, lactate and organic acids), inhibition of the urea cycle with hyperammoniemia, amino acid metabolic imbalance with hyperglycinemia and a reduction in branched fatty acids and an increase in the synthesis of odd-numbered long-chain fatty acids (OLCFA).

Clinically this disease commences with encephalopathy, serious metabolic acidosis, ketosis, hyperammoniemia, etc. and has subsequent serious after-effects. Biochemical control of the patient takes place in plasma (aminogram, acylcarnitines, OLCFA) and urine (organic acids). Treatment is with a diet that restricts natural proteins and cholesterol, giving special proteins that contain no methionine, threonine, valine or isoleucine and supplements with carnitine, while flagyl also has to be used to reduce intestinal flora. Its slow evolution may present progressive encephalopathy, myocardiopathy and anaemia that does not regenerate in spite of treatment.

There are no unique biochemical parameters for good or bad metabolic control to show that the diet is suitable, as the amount of proteins may vary in each patient, nor are there any predictive criteria for the evolution of patients with PA. We monitor so many that control is arduous and expensive for patients due to the taking of venous blood samples, for families because of travel and expenses, as well as the cost of health care.

The aims of this project are:

• To determine which biochemical tests are suitable and informative regarding patient state using monthly blood and urine samples deposited on paper in the patient's home. It is currently only possible to test for OLCFA and Coenzyme Q10 in liquid plasma every 3 months.
• To discover the frequency at which tests should take place to optimise nutritional and metabolic treatment.
• To avoid unnecessary travel by the family.