A compound heterozygote case of isolated sulfite oxidase deficiency

Abstract

We report an isolated sulfite oxidase deficiency in the first child boy of a non-consanguineous Caucasian family. He's a compound heterozygote for the sulfite oxidase gene, presenting low cystine, undetectable homocysteine and normal uric acid blood concentrations and undetectable sulfite oxidase activity in his cultured fibroblasts. Both mutations are not reported yet. The clinical presentation was typical and severe, with generalized status epilepticus and premature death.

Keywords: Compound heterozygote; Fibroblasts; Missense mutation; Point mutation; SUOX, sulfite oxidase; Sulfite oxidase activity; Transition; Transversion.

Fig. 1

Cerebral scan at the age of 20 months.

Fig. 2

SUOX gene DNA sequencing analysis. Panels A and B show sequencing results in the affected child and his mother, respectively. Sequences on both DNA strands are shown, the second strand being reversed complemented. The codon affected by the mutation is underlined. In each case, the normal sequence is listed on top and the mutated nucleotide is indicated below at the corresponding position. The resulting mutation is described at nucleotide and protein levels using HGVS (Human Genome Variation Society) standards.

Fig. 3

Alignment of the primary protein sequence of sulfite oxidase from different mammalian and non-mammalian species. Asterisks indicate the two conserved iron-binding histidine residues. The histidine and arginine residues affected by the mutation in the affected child are highlighted in black and are conserved among the different species.