Dietary practices in glutaric aciduria type 1 over 16 years.

BACKGROUND: In glutaric aciduria type 1 (GA1), dietary treatment with emergency management (EM) is essential to prevent encephalopathic crisis (EC). In the present study, dietary practices were examined in a single UK centre without access to newborn screening.
METHODS: Twenty GA1 patients (11 males, median age: 10.2 years, range 2.2-24.1 years) were evaluated. Nine presented without EC (median diagnosis age: 1.1 years, range 4 days to 8 years) and 11 with EC (median diagnosis age 10 months, range 6 months to 1.7 years). Dietary treatment, neurological outcome, anthropometry and biochemical/haematological markers were assessed.
RESULTS: Diet treatment varied according to age of diagnosis and symptom severity. Four of six pre-encephalopathic children diagnosed before 2 years of age were treated with carnitine, protein restriction (medium l.2 g kg day(-1)) and lysine-free/low tryptophan protein substitute (PS) (medium dose: 1.6 g kg day(-1)). EM consisted of natural protein cessation and glucose polymer with PS delivered via an enteral feeding tube. Older children (>3 years) without EC were given carnitine and protein restriction, and seven of nine EC patients had PS via an enteral feeding tube. Clinical deterioration occurred in two patients without EC; one taking PS and protein restriction (with a second untreatable pathology) and one after protein restriction only. In patients presenting with EC, four died and one had some improvement in movement, with the rest remaining stable but with severe disability. Patients taking PS had better nutritional markers [serum vitamin B(12) (P < 0.001), albumin (P < 0.001), haemoglobin (P < 0.001) and essential plasma amino acids].
CONCLUSIONS: Early diagnosis of GA1 before EC is essential because PS and protein restriction with meticulous EM prevents EC. PS also improves nutritional status irrespective of clinical condition.