Hi Muhammad

just go to the UCSC website, you have a genome browser and a table browser. all the available options you'll got on the genome browser will help you getting the sequence of your requested exon (in variation/common SNP...). zooming at the right sequence of your protein you'll got your answer.

fred

Mutated exons can be easily found by downloading the transcripts of a gene from any of the transcript databases like Unigene and doing a multiple sequence alignment of the transcripts along with the genomic sequence of the gene to locate the mutation

The easiest way to align genomic and mRNA (cDNA):

https://www.ncbi.nlm.nih.gov/sutils/splign/splign.cgi?textpage=online&level=form

checking mutated vs. non-mutated alignments will rapidly drive you to a better analysis, also you may understand splicing differences due to mutations.