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.
ABSTRACT
The clinical data of a case with late-onset isolated sulfite oxidase deficiency(ISOD)admitted in the Department of Neurology, Children′s Hospital, Zhejiang University School of Medicine in July 2021 were retrospectively analyzed.Fifteen previously published cases of late-onset ISOD were also reviewed.The patient was a girl, who was hospitalized because of " motor regression with mental retardation for 5 days" at 1 year old.The manifestations of the patient were extrapyramidal symptoms, regression of motor development and seizures.The level of urinary sulfites in the patient was increased.Magnetic resonance imaging (MRI) features were bilateral pallidus and substantia nigra.Gene sequencing suggested a pure missense mutation of the sulfite oxidase( SUOX) gene c. 650(exon5)G>A(p.Arg217Gln). In 16 cases of late-onset ISOD, the median age at onset and diagnosis was 10.5 months and 34.0 months, respectively.The common clinical manifestations were hypotonia (13 cases), seizures (10 cases), movement disorders (9 cases), and ectopia lentis (6 cases). The most common brain MRI feature was pallidus changes (11 cases), followed by lesions of substantia nigra (5 cases), and cerebral atrophy (4 cases). Fourteen cases of late-onset ISOD showed a positive urinary sulfite test.The missense mutation of the SUOX gene was found in 9 cases.It suggested that brain MRI involvement of bilateral pallidus, high excretion of urine sulfites and the missense mutation of the SUOX gene were important diagnostic clues for late-onset ISOD.
ABSTRACT
Sulfite oxidase [SO; EC 1.8.3.1] catalyses the physiologically vital oxidation of sulfite to sulfate, the terminal reaction in degradation of sulfur containing amino acids, cysteine and methionine. Sulfite oxidase from vertebrate sources is among the best studied molybdenum enzymes. Existence of SO in plants has been established recently by identification of a cDNA from Arabidopsis thaliana encoding a functional SO. The present study was undertaken to identify herbaceous and woody plants (viz., Azardirachta indica L., Cassia fistula L., Saraca indica L., Spinacea oleracea L., and Syzyzium cumini L.), a relatively less explored source, having significant SO activity and to characterize some of its immuno-biochemical properties. The Syzyzium cumini was chosen to characterize SO as it showed maximum enzyme activity in the crude extract as compared to other plants. Absorption spectra of SO revealed two peaks at 235 and 277 nm, but no distinct peak in the visible region could be observed. Crude extract of all the plants were taken into considerations for immuno-biochemical studies. Despite of significant protein structure-functional similarities between plant and animal SO, no cross-reactivity could be established between the two sources of SO. These data suggested that plants SO, however, differed with regards to their immuno-biochemical properties.