Results of a study in this week’s issue of THE LANCET support the introduction of early screening for the metabolic disease medium-chain acyl-CoA dehydrogenase (MCAD) deficiency.
MCAD deficiency is a metabolic disorder which affects up to 1 in 9000 people in the UK. It can be controlled with appropriate carbohydrate intake, but is especially severe in children who develop neurological damage arising from encephalopathy before the disorder is diagnosed. MCAD deficiency leads to the accumulation of octanoylcarnitine in the blood of patients. The deficiency can, therefore, be diagnosed by analysis of concentration of acylcarnitines in blood spots. Screening for MCAD deficiency-which is done in parts of the USA, Germany, and Australia-has not yet been introduced in the UK, primarily because of uncertainty about the natural history of the disorder and concerns about the accuracy of the test to identify it.
Morteza Pourfarzam and colleagues from the Royal Victoria Infirmary, Newcastle upon Tyne, UK, did a retrospective study in which the concentrations of acylcarnitines in around 100 000 stored blood spots from infants in the north of England were analysed; patients with high octanoylcarnitine concentrations at age 7-9 years, indicating MCAD deficiency, were assessed. 8 patients were accurately identified with MCAD deficiency (combination of high octanoylcarnitine concentration [0.3 mmol/litre] and a ratio of octanoylcarnitine to hexanoylcarnitine greater than 4.0).
Morteza Pourfarzam comments: "The high illness and death associated with the disorder, and the specificity of acylcarnitine analysis seen in our study support the introduction of screening for MCAD deficiency."
Contact: Dr Morteza Pourfarzam, Department of Child Health, The Royal Victoria Infirmary, Queen Victoria Road, Newcastle upon Tyne, NE1 4LP, UK; T) 44-191-202-3033; F) 44-191-202-3022; E) morteza.pourfarzam@ncl.ac.uk
Journal
The Lancet