Dietary management of inborn errors of amino acid metabolism with protein-modified diets

Automated therapy preparation of isoleucine formulations using 3D printing for the treatment of MSUD: First single-centre, prospective, crossover study in patients

Maple syrup urine disease (MSUD) is a rare metabolic disorder with a worldwide prevalence of 1 in every 185,000 live births. However, certain populations display a significant overexpression of the disorder where incidence is reported to be 1 in every 52,541 new-borns. The first-line therapy for MSUD involves a strict dietary leucine restriction and oral supplementation of isoleucine and valine. The dose administered to patients requires strict tailoring according to age, weight and blood levels. In current clinical practice, however, practitioners still have to prepare extemporaneous formulations due to the lack of suitable oral treatments for MSUD. Herein, we evaluate the first time use of 3D printing in a hospital setting for the preparation of personalised therapies with the aim of improving safety and acceptability to isoleucine supplementation in paediatric patients suffering from MSUD. This investigation was a single-centre, prospective crossover experimental study. Four paediatric patients with MSUD (aged 3-16 years) were treated at the Clinic University Hospital in Santiago de Compostela, Spain which is a MSUD reference hospital in Europe. The primary objective was to evaluate isoleucine blood levels after six months of treatment with two types of formulations; conventional capsules prepared by manual compounding and personalised chewable formulations prepared by automated 3D printing. A secondary investigation was to evaluate patient acceptability of 3D printed formulations prepared with different flavours and colours. Isoleucine blood levels in patients were well controlled using both types of formulations, however, the 3D printed therapy showed mean levels closer to the target value and with less variability (200-400 µM). The 3D printed formulations were well accepted by patients regarding flavour and colour. The study demonstrates for the first time that 3D printing offers a feasible, rapid and automated approach to prepare oral tailored-dose therapies in a hospital setting. 3D printing has shown to be an effective manufacturing technology in producing chewable isoleucine printlets as a treatment of MSUD with good acceptability.

Single amino acid supplementation in aminoacidopathies: a systematic review

Aminoacidopathies are a group of rare and diverse disorders, caused by the deficiency of an enzyme or transporter involved in amino acid metabolism. For most aminoacidopathies, dietary management is the mainstay of treatment. Such treatment includes severe natural protein restriction, combined with protein substitution with all amino acids except the amino acids prior to the metabolic block and enriched with the amino acid that has become essential by the enzymatic defect. For some aminoacidopathies, supplementation of one or two amino acids, that have not become essential by the enzymatic defect, has been suggested. This so-called single amino acid supplementation can serve different treatment objectives, but evidence is limited. The aim of the present article is to provide a systematic review on the reasons for applications of single amino acid supplementation in aminoacidopathies treated with natural protein restriction and synthetic amino acid mixtures.

[3-Hydroxy-3-methyl-glutaryl-CoA-lyase deficiency as coma etiology in the neonatal period: case report]

We report a patient that presented two episodes of coma in the neonatal period, with severe metabolic acidosis and hypoglycemia, without ketosis. The urinary organic acid analysis showed increased amounts of 3-hydroxy-3-methyl-glutaric, 3-methylglutaconic, 3-methylglutaric and 3-hydroxyisovaleric acid. The deficiency of 3-hydroxy-3-methylglutaryl-CoA lyase was diagnosed by the clinical and metabolic features. This disease shows autosomal recessive inheritance and the treatment is done by a diet with restriction of protein (mainly leucine) and lipids, high in carbohydrate content, and the avoidance of fasting and carnitine supplementation.

Unusual presentations of propionic acidemia

The files of 25 patients with propionic acidemia (PA), followed by the Inborn Errors of Metabolism Service (IEMS) at King Faisal Specialist Hospital and Research Centre (KFSH & RC) from 1990 to 1993, were studied retrospectively. In 14 patients PA presented acutely with acidosis, hyperammonemia and thrombocytopenia, while in 11 patients the presentation of the disease was unusual. In the latter group, two neonates with PA initially appeared as a primarily hyperammonemic metabolic disease. In two other neonates the vomiting was so severe that they were diagnosed as intestinal obstruction in referral hospitals. The presentation in three infants was primarily as an immune disorder. In four infants, PA appeared as an acute or chronic encephalopathy, i.e. as a silent organic acidemia, with few other findings of the disease. The clinical picture of PA includes facial and nipple dysmorphia, severe hypotonia and vomiting. Severe thrombocytopenia is the hallmark of the metabolic crisis. In one patient it was noticed late and caused intracranial hemorrhage, while in three others intracranial bleeding caused death. The prognosis in PA remained grave despite rigorous treatment. Only seven of the 25 PA patients remained to have a normal life-style, while eight patients expired. The diagnosis is readily achieved by urine gas chromatography/mass spectrometry (GC/MS), by tandem mass spectrometry (MS/MS), or by enzyme analysis of fibroblasts. While there may be both examiner- and patient-related reasons for the variations in the presentation of PA, one other reason may be the heterogeneity of the molecular defect in propionyl-CoA carboxylase.

A study of the response to protein-modified diets for propionic acidemia in twelve patients

The charts of twelve patients with propionic acidemia (PA) were analyzed retrospectively for the outcome of dietary treatment. The diet was prescribed for each patient based on their individual needs. We established good diet compliance in four PA patients who were alive and well with healthy life-styles at the time of this report. The main difficulty causing non-compliance was the parents' inability to take care of the patient due to other family responsibilities. In two cases, the parents believed their children to be cured and they abandoned diet and medications, resulting in the sudden death of both children. In four cases, the parents were unable to cope with the demands of the diet and medications, while complications and severe classic PA provided no hope for two patients.

Emergency presentations of patients with methylmalonic acidemia, propionic acidemia and branched chain amino acidemia (MSUD)

The charts of 16 patients with branched chain amino acidemia (MSUD) who had 48 emergency room (ER) visits, of 10 patients with propionic acidemia (PA) who had 57 ER visit, and of 13 patients with methylmalonic acidemia (MMA) who had 154 ER visits, were reviewed retrospectively for the most common clinical presentations, physical and laboratory findings. The most common clinical presentation was acute or chronic vomiting and the most common physical finding was dehydration. When hypoglycemia was found, the mental status of 55% of patients with MSUD and MMA and 20% of patients with PA, was alert. Mixed acid/base disturbance, i.e. alkalosis caused by vomiting mixed with metabolic acidosis caused by the disease, was present in 30% of MSUD, in 33% of PA, and 45% of MMA. There was no relationship between acidosis detected by the blood pH and mental status of the patients. A good correlation between base excess < -5 and serum bicarbonate < 21 mmol/l was found. Blood cultures were positive for bacteria and fungi in 15% of the visits with MSUD, in 23% with PA, and 3% with MMA. Patients with positive blood cultures did not necessarily have a temperature > 39 degrees C nor hypothermia. The results suggest that the mental status of the patients should not detract the ER physician from obtaining blood pH, gases and glucose and in all instances a blood culture should be secured, even if the patient has no fever.

Liposomal amphotericin-B (AmBisome) for treatment of cutaneous widespread candidosis in an infant with methylmalonic acidaemia

In a 10-week-old infant with vitamin B12-unresponsive methylmalonic acidaemia, cutaneous candidosis (Candida albicans) progressed rapidly despite topical antifungal treatment. After 1 week of intravenous therapy with liposomal amphotericin-B (AmBisome) the dermatitis disappeared completely and blood cultures were sterile. No side-effects were observed. This is one of the first experiences in the treatment of infants with this new antifungal agent.