Trinucleotide insertion in the @entity23247 promoter may not be related to the clinical phenotype of XXXX .

@entity1 @entity2057 @entity23247 @entity11280
BACKGROUND: More than 90% of @entity2057 ( @entity2057 ) @entity1 show homozygous deletion of @entity11280 ( @entity11280 ). They retain @entity23247 , a highly homologous gene to @entity11280 , which may partially compensate for deletion of @entity11280 . Although the promoter sequences of these two genes are almost identical, a GCC insertion polymorphism has been identified at c.-320_-321 in the @entity11280 promoter. We have also found this insertion polymorphism in an @entity23247 promoter in an @entity2057 @entity1 ( @entity1 A) who has @entity2057 type 2/3. PURPOSE: The aims of this study were to determine the frequency of the GCC insertion polymorphism in @entity2057 @entity1 , and to evaluate its effect on SMN transcription efficiency. @entity1 AND METHODS: Fifty-one @entity2057 @entity1 , including @entity1 A, were involved in this study. @entity23247 transcript levels in white blood cells were measured by real-time polymerase chain reaction. Screening of the GCC insertion polymorphism was performed using denaturing high-pressure liquid chromatography. The transcription efficiency of the promoter with the insertion mutation was evaluated using a reporter-gene assay. RESULTS: All @entity2057 @entity1 in this study were homozygous for @entity11280 deletion. @entity1 A retained two copies of @entity23247 , and showed only a small amount of @entity23247 transcript in white blood cells. We detected a GCC insertion polymorphism at c.-320_-321 only in @entity1 A, and not in 50 other @entity2057 @entity1 . The polymorphism had a slight but significant negative effect on transcription efficiency. DISCUSSION AND CONCLUSION: @entity1 A was judged to be an exceptional case of @entity2057 , because the GCC insertion polymorphism rarely exists in @entity11280 -deleted @entity2057 @entity1 . The GCC insertion polymorphism did not enhance the transcriptional efficiency of @entity23247 . Thus, this GCC insertion polymorphism in the @entity23247 promoter may not be associated with the milder phenotype of the @entity1 . @entity1 A suggests that there are other unknown factors modifying the clinical phenotype of @entity2057 .
