The Turkish Journal of Pediatrics 2021 , Vol 63 , Num 4
Severe isolated sulfide oxidase deficiency with a novel mutation
Meriç Ergene 1 ,Nuriye Yarar 1 ,Elif Perihan Öncel 2 ,Taner Sezer 2 ,Büşranur Çavdarlı 3 ,İsmail Zafer Ecevit 4 ,Halil İbrahim Aydın 5
1 Department of Pediatrics, Başkent University Faculty of Medicine, Ankara
2 Divisions of Pediatric Neurology, Başkent University Faculty of Medicine, Ankara
3 Department of Medical Genetics, Ankara City Hospital, Ankara, Turkey
4 Department of Pediatric Infectious Diseases, Başkent University Faculty of Medicine, Ankara
5 Department of Pediatric Metabolism and Nutrition, Başkent University Faculty of Medicine, Ankara
DOI : 10.24953/turkjped.2021.04.021 Background. Isolated sulfite oxidase deficiency (ISOD), caused by mutations in SUOX gene, is an autosomal recessive disease manifesting with early onset seizures, developmental delay, microcephaly, and spasticity. It mimics hypoxic-ischemic encephalopathy (HIE) in the neonatal period and is characterized by progressive severe neurological impairment due to accumulation of toxic metabolites.

Case. This report presents a late diagnosed male patient with ISOD manifesting with neonatal-onset seizures, developmental delay, microcephaly, and spastic quadriplegia. Brain magnetic resonance imaging of the patient showed bilateral subcortical multi-cystic encephalomalacia involving bilateral parieto-occipital regions. A novel homozygous c.590_595delAGCCTC in-frame deletion in SUOX gene was identified in the patient, while both parents were heterozygous for that mutation.

Conclusion. The mutation identified in our patient causes severe ISOD. Early diagnosis of ISOD is essential for accurate genetic counseling and achieving prenatal diagnosis. Screening for urinary sulfite in patients with neonatal or early infantile onset seizures, developmental delay, microcephaly and cystic encephalomalacia in neuroimaging mimicking HIE helps in early diagnosis. Keywords : sulfite oxidase, isolated sulfite oxidase deficiency, ISOD, SUOX, seizure

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