CASE REPORT Straight-chain acyl-CoA oxidase de¢ciency presenting with dysmorphia, neurodevelopmental autistic-type regression and a selective pattern of leukodystrophy M. A. Kurian 1 , S. Ryan 2 , G. T. N. Besley 3 , R. J. A. Wanders 4 and M. D. King 1 * 1 Department of Paediatric Neurology, 2 Department of Paediatric Radiology, The Children’s University Hospital, Dublin, Ireland; 3 Willink Biochemical Genetics Unit, Royal Manchester Children’s Hospital, Manchester, UK; 4 Department of Paediatrics and Clinical Chemistry, AMC, University Hospital, Amsterdam, The Netherlands *Correspondence: Department of Paediatric Neurology, The Children’s University Hospital, Dublin 1, Ireland. E-mail: mary.king@tsch.ie Summary: We report a rare case of straight-chain acyl-CoA oxidase deficiency (McKusick 264470) presenting with dysmorphism, neurodevelopmental regression and leukodystrophy. The catabolic function of peroxisomes includes the b-oxidation of very long-chain fatty acids (VLCFA). Disorders of peroxisome function are rare, and defects result either from failure of peroxisome biogenesis or from specific enzyme deficiencies. The following report describes a rare case of straight-chain acyl-CoA oxidase deficiency (McKusick 264470) presenting with dysmorphism, neurodevelopmental regression and leukodystrophy. A 10-month-old girl, the ¢rst child of unrelated parents, presented with a 3-month history of developmental regression. Asymmetrical intrauterine growth retardation andoligohydramnioscomplicatedthepregnancy.Thebirthwasuneventfulandallearly developmental milestones had been reached appropriately. Development continued normally until 7 months of age. After this she was noted to lose previously acquired skills and was not gaining new skills. She developed irritability, abnormal stereotypical movements and an excessive startle response to auditory stimuli. Dysmorphic features included brachycephaly, marked frontal bossing, a broad, depressed nasal bridge, mild hypertelorism, an intermittent bilateral convergent squint and bilateral nipple inversion. The anterior fontanelle was large (3 cm  4cm). On neurological examination at 10 months, there was an abnormal monotonous cry and marked axial and peripheral hypotonia. There was no eye contact, social interaction,vocalizationorimitativeplay,withdevelopmentalstagebelowthe4-month level. Mild hepatomegaly was also present and ultrasound scan of the liver showed di¡usely increased echogenicity suggestive of fatty in¢ltration. An ophthalmological assessmentshowedleftsubretinalpigmentaryretinopathy.Brainstemevokedresponses showed bilateral sensory hearing loss below 60 dB. An electroencephalogram, visual evoked responses, electroretinogram and CT brain scan were all normal. J. Inherit. Metab. Dis. 27(2004)105^108 # SSIEMandKluwerAcademicPublishers.PrintedintheNetherlands 105