*Thyroid function: (a) boy presented at 1 year 10 months as a placid baby with EDI most obvious in motor skills and with hypotonia. Autoimmune hypothyroidism diagnosed and he improved with treatment although subsequently developed ASD; (b) ex-preterm (29 weeks) girl investigated at 4 years 7 months to a mother with learning difficulties, had general developmental impairment, especially in speech skills who improved on treatment but had attention and behavioural difficulties; (c) girl investigated at 5 years 6 months for EDI, nystagmus with a history of maternal illicit drug use in pregnancy—showed improvement on treatment, but not to normal abilities. Dual diagnosis is being investigated.

†Plasma amino acids: (a) boy investigated at 4 years 1 month with EDI and seizures whose brother had similar phenotype diagnosed with homocystinuria; (b) 4-month-old boy with EDI, microcephaly, hypertonia and poor visual function with low serum and CSF serine, diagnosed with serine deficiency; (c) girl investigated at 2 years 11 months with EDI, brittle hair, eczema and dysmorphia diagnosed with ethylmalonic aciduria; (d) boy investigated at 4 years 7 months with EDI and faltering growth diagnosed with lysinuric protein intolerance; (e) boy investigated at 10 months with EDI, visual impairment and hypotonia noted to have low serum and CSF serine, diagnosed as serine deficiency.

‡Urine organic acids: ex-premature girl investigated at 8 months for EDI, acquired microcephaly and faltering growth with raised lactate and glutamate, subsequently diagnosed with pyruvate dehydrogenase deficiency; see cases (c) and (d) in the plasma amino acid results.

ASD, Autistic spectrum disorder; CSF, cerebrospinal fluid; CK, creatine kinase; EDI, early developmental impairment; FBC, full blood count; GAG, glycosaminoglycans; LFT, liver function test; TFT, thyroid function test; U&E, urea and electrolytes; ZPP, zinc protoporphyrin;