Authors: Jens Michael Hertz Ulf Persson Inger Juncker Mårten Segelmark
Publish Date: 2005/08/17
Volume: 118, Issue: 1, Pages: 23-28
Abstract
The Xlinked form of Alport syndrome AS is caused by mutation in the COL4A5 gene located at Xq223 and encoding the α5chain of type IVcollagen More than 400 different mutations have so far been detected in the COL4A5 gene Not all mutations however will be detected using an exonbyexon mutation detection strategy such as SSCP analysis or direct sequencing We have previously reported the results of SSCP analysis of 81 patients suspected of Xlinked AS Genomic DNA from these 81 patients was also analyzed for larger genomic rearrangements using Southern blotting analysis Abnormal band patterns were found in three patients two of which were caused by single base substitutions in the coding region also detected by the SSCP analysis Here we report the results of the analysis of a larger structural COL4A5 rearrangement that escaped the SSCP analysis The rearrangement was found to be an inversion of a 21 Mb fragment of the COL4A5 gene comprising exon 9 through 51 with proximal breakpoint within intron 8 at Xq223 and a distal breakpoint 56 kb upstream to the initiation codon in the RAB33A gene at Xq25 The inversion of exon 9 through 51 is expected to result in a truncated or absent α5IVchain and has not previously been associated with AS These findings emphasize the need for a supplement to mutation detection strategies such as SSCP analysis and direct sequencing in order to detect more complicated structural COL4A5 rearrangements Larger structural rearrangements constitute 23 1/43 of the mutations in the present material
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