Mutation of the sterol 27-hydroxylase gene (CYP27) results in truncation of mRNA expressed in leucocytes in a Japanese family with cerebrotendinous xanthomatosis.
OBJECTIVE
A Japanese family with cerebrotendinous xanthomatosis (CTX) was investigated for a sequence alteration in the sterol 27-hydroxylase gene (CYP27). The expression of CYP27 has been mostly explored using cultured fibroblasts, prompting the examination of the transcripts from blood leucocytes as a simple and rapid technique.


METHODS
An alteration in CYP27 of the proband was searched for by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis and subsequent sequencing. Samples of RNA were subjected to reverse transcription PCR (RT-PCR) and the product of the proband was amplified with nested primers and sequenced.


RESULTS
A homozygous G to A transition at the 5' end of intron 7 was detected in the patient. In RT-PCR analysis, only a truncated transcript was detected in the patient, whereas both normal and truncated transcripts were detected in the siblings. The sequencing of the patient's cDNA fragment disclosed a direct conjuction of exon 6 and exon 8.


CONCLUSIONS
The mutation at splice donor site and the truncation of mRNA were identical with those of a recently reported Italian patient, although different in symptomatology. The application of blood leucocytes can be a simple technique on analysing a constructive abnormality of CYP27 mRNA.
Shiga
K
K
Department of Dynamic Pathology, Kyoto Prefectural University of Medicine, Kyoto, Japan.
Fukuyama
R
R
Kimura
S
S
Nakajima
K
K
Fushiki
S
S
D000328:Adult; D000595:Amino Acid Sequence; D053493:Cholestanetriol 26-Monooxygenase; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics*; D018076:DNA, Complementary / Q000032:analysis; D005091:Exons / Q000235:genetics; D006801:Humans; D007564:Japan; D007962:Leukocytes / Q000201:enzymology; D008297:Male; D008969:Molecular Sequence Data; D017354:Point Mutation; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013250:Steroid Hydroxylases / Q000235:genetics*; D019294:Xanthomatosis, Cerebrotendinous / Q000235:genetics*
D018076:DNA, Complementary; D012333:RNA, Messenger; D003577:Cytochrome P-450 Enzyme System; D013250:Steroid Hydroxylases; C506831:CYP27A1 protein, human; D053493:Cholestanetriol 26-Monooxygenase