Table 1.

Tiers of imaging, chromosomal and metabolic tests currently performed in Victorian pediatric centres (Pathway 1), and their associated costs including admission and procedural costs where relevant in US dollars^*.

	Tests	Cost*
Tier 1	MRI-brain under general anaesthetic Blood tests: chromosomal microarray, full blood count, electrolytes, urea and creatinine, glucose, calcium, magnesium, phosphate, liver function tests, lactate, ammonia, amino acids, acylcarnitines, biotinidase, uric acid Urine tests: organic acids, amino acids, piperideine-6-carboxylate, S-sulphocysteine, guanidinoacetic acid, purines and pyrimidines	$3,202
Tier 2	Blood tests: common mitochondrial mutations, POLG common mutations, transferrin isoforms, copper and caeruloplasmin, very long chain fatty acids, white cell enzymes, glucose^, lactate^, pyruvate^, amino acids^ Cerebrospinal fluid tests: cell count, protein, glucose, lactate, pyruvate, amino acids, neurotransmitters	$2,184
Repeat MRI-brain	Performed at 3 Tesla using epilepsy protocol sequences under general anaesthetic	$1,565
Tier 3	Skin biopsy: electron microscopy for changes of neuronal ceroid lipofuscinosis, lysosomal and mitochondrial disorders, fibroblast culture (for DNA source) Liver and muscle biopsies: histopathology, histochemistry, electron microscopy, respiratory chain enzyme analysis	$5,309

^*See Tables S3 and S4 for detailed breakdown of costs and their sources

^{^}Paired with cerebrospinal fluid