Decreased plasma L-arginine levels in organic acidurias (MMA and PA) and decreased plasma branched-chain amino acid levels in urea cycle disorders as a potential cause of growth retardation: Options for treatment

Background and aim: Patients with methylmalonic acidemia (MMA) and propionic acidemia (PA) and urea cycle disorders (UCD), treated with a protein restricted diet, are prone to growth failure. To obtain optimal growth and thereby efficacious protein incorporation, a diet containing the essential and functional amino acids for growth is necessary. Optimal growth will result in improved protein tolerance and possibly a decrease in the number of decompensations. It thus needs to be determined if amino acid deficiencies are associated with the growth retardation in these patient groups. We studied the correlations between plasma L-arginine levels, plasma branched chain amino acids (BCAA: L-isoleucine, L-leucine and L-valine) levels (amino acids known to influence growth), and height in MMA/PA and UCD patients. Methods: We analyzed data from longitudinal visits made in stable metabolic periods by patients registered at the European Registry and Network for Intoxication Type Metabolic Diseases (E-IMD, Chafea no. 2010 12 01). Results: In total, 263 MMA/PA and 311 UCD patients were included, all aged below 18 years of age. In patients with MMA and PA, height z-score was positively associated with patients' natural-protein-to-energy prescription ratio and their plasma L-valine and L-arginine levels, while negatively associated with the amount of synthetic protein prescription and their age at visit. In all UCDs combined, height z-score was positively associated with the natural-protein-to-energy prescription ratio. In those with carbamylphosphate synthetase 1 deficiency (CPS1-D), those with male ornithine transcarbamylase deficiency (OTC-D), and those in the hyperornithinemia-hyperammonemia-homocitrullinuria (HHH) syndrome subgroup, height z-score was positively associated with patients' plasma L-leucine levels. In those with argininosuccinate synthetase deficiency (ASS-D) and argininosuccinate lyase deficiency (ASL-D), height was positively associated with patients' plasma L-valine levels. Conclusion: Plasma L-arginine and L-valine levels in MMA/PA patients and plasma L-leucine and L-valine levels in UCD patients, as well as the protein-to-energy prescription ratio in both groups were positively associated with height. Optimization of these plasma amino acid levels is essential to support normal growth and increase protein tolerance in these disorders. Consequently this could improve the protein-to-energy intake ratio

Evaluation of dietary treatment and amino acid supplementation in organic acidurias and urea-cycle disorders

Collaborators :Hörster F, Matzkuhn H, Mütze U, Kowoll ME, Dressel M, Jelsig AM, de Lonlay P, Wijburg FA, Bosch A, Freisinger P, Jeltsch K, Posset R, Boy N, Mengler K, Augoustides-Savvopoulou P, Avram P, Deleanu C, Baumgartner MR, Häberle J, Blasco-Alonso J, Burlina AB, Rubert L, Cazorla AG, Saladelafont ECI, Dionisi-Vici C, Martinelli D, Dobbelaere D, Mention K, Grünewald S, Chakrapani A, Hwu WL, Chien YH, Lee NC, Karall D, Scholl-Bürgi S, Lachmann R, De Laet C, Matsumoto S, de Meirleir L, Mühlhausen C, Schiff M, Peña-Quintana L, Djordjevic M, Sarajlija A, Sykut-Cegielska J, Wisniewska A, Leao-Teles E, Alves S, Vara R, Vives-Pinera I, Ortega DG, Morris A, Zeman J, Honzik T, Chabrol B, Arnaudo F, Cano A, Thompson N, Eyskens F, Lindner M, Lüsebrink N, Jalan A, Sokal E, Legros V, Nassogne MC. INTRODUCTION: Organic acidurias (OAD) and urea-cycle disorders (UCD) are rare inherited disorders affecting amino acid and protein metabolism. As dietary practice varies widely, we assessed their long-term prescribed dietary treatment against published guideline and studied plasma amino acids levels. METHOD: We analyzed data from the first visit recorded in the European registry and network for intoxication type metabolic diseases (E-IMD, Chafea no. 2010 12 01). RESULTS: In total, 271 methylmalonic aciduria (MMA) and propionic aciduria (PA) and 361 UCD patients were included. Median natural protein prescription was consistent with the recommended daily allowance (RDA), plasma L-valine (57%) and L-isoleucine (55%) levels in MMA and PA lay below reference ranges. Plasma levels were particularly low in patients who received amino acid mixtures (AAMs-OAD) and L-isoleucine: L-leucine: L-valine (BCAA) ratio was 1.0:3.0:3.2. In UCD patients, plasma L-valine, L-isoleucine and L-leucine levels lay below reference ranges in 18%, 30% and 31%, respectively. In symptomatic UCD patients who received AAM-UCD, the median natural protein prescription lay below RDA, while their L-valine and L-isoleucine levels and plasma BCAA ratios were comparable to those in patients who did not receive AAM-UCD. Notably, in patients with ornithine transcarbamylase syndrome (OTC-D), carbamylphosphate synthetase 1 syndrome (CPS1-D) and hyperammonemia-hyperornithinemia-homocitrullinemia (HHH) syndrome selective L-citrulline supplementation resulted in higher plasma L-arginine levels than selective L-arginine supplementation. CONCLUSION: While MMA and PA patients who received AAMs-OAD had very low BCAA levels and disturbed plasma BCAA ratios, AAMs-UCD seemed to help UCD patients obtain normal BCAA levels. In patients with OTC-D, CPS1-D and HHH syndrome, selective L-citrulline seemed preferable to selective L-arginine supplementation. This article is protected by copyright. All rights reserved