Neonatal isolated sulfite oxidase deficiency: a case report and literature review / 中国新生儿科杂志

ABSTRACT

Objective:To study the clinical and laboratory characteristics of neonatal isolated sulfite oxidase deficiency (ISOD).Methods:An infant with neonatal ISOD admitted to our hospital was retrospectively analyzed. Using key words "isolated sulfite oxidase deficiency", "SUOX gene", "Infant, newborn", databases including CNKI, Wanfang database, National library and literature center of science and technology, China science paper online, PubMed, Web of Science and EMBASE (up to January 2021) were searched and literature review was conducted. The clinical manifestations, laboratory results, treatment and prognosis were analyzed.Results:Our patient was a full-term male infant with eye movement disorder, refractory seizures, feeding difficulties, increased muscle tone, developmental retardation and microcephaly. Urine sulfite paper-strip test was positive. Uric acid was normal. Whole exon sequencing (WES) revealed SUOX c.475G>T and c.1201A>G compound heterozygous mutations. Cranial MRI showed multiple encephalomalacia and brain atrophy at 5-month of age. The infant died at 8-month. In the literature review, a total of 29 articles and 32 cases of neonatal ISOD were found. 87.5% of the cases developed symptoms within 1-week after birth. All had convulsive seizures. Some of them had feeding difficulties, muscle tone changes, developmental retardation, microcephaly and ectopia lentis. Cranial imaging showed white matter cystic lesions and brain atrophy. Laboratory examination showed elevated urinary sulfite and S-sulfocysteine. Uric acid and xanthine/hypoxanthine were normal. Blood homocysteine was decreased. 23 cases received genetic testing and all of them had SUOX mutations. The treatment was mainly symptomatic relief and supportive treatment. During follow-up, 15 cases died, 13 cases survived and 4 cases were unknown. All the surviving children had drug-resistant convulsions and developmental retardation.Conclusions:Neonatal ISOD may present with refractory convulsions, feeding difficulties and developmental retardation. Cystic white matter changes and brain atrophy may be seen on cranial imaging. Elevated urinary sulfites, decreased blood homocysteine and normal uric acid are important clues for diagnosis. Genetic testing is helpful for early diagnosis.