Novel point mutations in the steroid sulfatase gene in patients with X-linked ichthyosis: transfection analysis using the mutated genes.
X-linked ichthyosis is caused by steroid sulfatase deficiency which results from abnormalities in its coding gene. The majority of X-linked ichthyosis patients ( approximately 90%) have complete or partial deletions of the steroid sulfatase gene. In this study, we examined the mutations of the steroid sulfatase gene in two unrelated X-linked ichthyosis patients without complete deletion of the gene. Polymerase chain reaction-single-strand conformation polymorphism and direct sequencing analyses showed that each patient has a different single base pair substitution within exon 8 encoding the C-terminal half of the steroid sulfatase polypeptide. Both mutations resulted in the transversion of functional amino acids: a G-->C substitution at nucleotide 1344, causing a predicted change of a glycine to an arginine, and a C-->T substitution at nucleotide 1371, causing a change from a glutamine to a stop codon. In vitro steroid sulfatase cDNA expression using site-directed mutagenesis revealed that these mutations are in fact pathogenic and reflect the levels of steroid sulfatase enzyme activities in each of the X-linked ichthyosis patients.
Oyama
N
N
Department of Dermatology, Fukushima Medical University School of Medicine, Japan.
Satoh
M
M
Iwatsuki
K
K
Kaneko
F
F
D000328:Adult; D001192:Arylsulfatases / Q000235:genetics*; D017353:Gene Deletion; D006801:Humans; D007057:Ichthyosis / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D017354:Point Mutation; D043266:Steryl-Sulfatase; D014162:Transfection; D014960:X Chromosome
D001192:Arylsulfatases; D043266:Steryl-Sulfatase