Counselling a family after a new maple syrup urine disease diagnosis — OSCE

The parents of a five-day-old boy sit with you on the neonatal unit. He was well at birth but deteriorated at 72 hours with lethargy, vomiting, opisthotonus and seizures; he had a high anion-gap metabolic acidosis with ketosis and a maple-syrup odour, and a markedly elevated leucine with pathognomonic allo-isoleucine confirming maple syrup urine disease. He was stabilised with glucose and insulin and intralipid, a branched-chain-amino-acid-free formula, and haemofiltration. The parents are frightened, blame themselves for not bringing him in sooner, have read about experimental 'cures' online, and are terrified he could die suddenly at home. Counsel them.