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Invest Ophthalmol Vis Sci. 1998 Aug;39(9):1736-9.

Novel mutations in the XLRS1 gene may be caused by early Okazaki fragment sequence replacement.

Author information

1
National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.

Abstract

PURPOSE:

To determine whether two families diagnosed with X-linked retinoschisis contained mutations in the XLRS1 gene.

METHODS:

DNA from the patients was obtained from blood lymphocytes using commercially available kits. Single-strand conformation assay was performed in an electrophoresis apparatus using 10% acrylamide TBE gels at 10 degrees C. The gels were stained with SYB green II and were scanned in a phosphoimager. DNA was sequenced using an automated fluorescence sequencer.

RESULTS:

A deletion that eliminates exon 2 was found in one family. An abnormal sequence replacement in exon 4 was found in the other family. Both mutations have severe effects in the coding region by inserting premature stop codons.

CONCLUSIONS:

Both of the families have mutations in the XLRS1 gene. One of these mutations points to a novel mechanism. The mutation is caused by a replacement of 17 bp of a normal sequence with 20 bp of a sequence originating from two different places in the antisense strand. This suggests that early Okazaki fragments were incorporated into the sense strand of exon 4, replacing the normal sequence.

PMID:
9699564
[Indexed for MEDLINE]

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