Because we did not know whether they were on the same chromosome, we cloned a promoter with these two mutations. The promoter activity was even lower when these two mutations were on the same haplotype. The mutations in the 5′ UTR were analyzed using the promoter analysis tool21 with International Union for Pure and Applied Chemistry consensus

strings of the transcription factor binding site. The −215AT and −133AC mutations abolished BTK inhibitor the activator protein 1 (AP1) and specificity protein 1 (SP1) transcription factor binding sites, respectively.21 These mutations may interfere with normal regulation of the ATP7B gene, leading to WD. Alternative splicing is important in medicine because it is the major source of proteome diversity. Selleck CCI-779 Alternatively spliced protein isoforms may have indistinguishable, related, diverse, or antagonistic functions.22, 23 The ATP7B gene exhibits a tissue-specific splicing pattern.9 Most ATP7B transcripts in the liver have all the exons found in the genomic DNA, whereas splice variants in the brain have several combinations of skipped exons. Skipping exons 6, 7, 8, 12, and 13 maintains the open reading frame

of the gene; however, the function of alternatively spliced variants of ATP7B is unknown. We have demonstrated that alternatively spliced variants of exon 12 retained 80% of wild-type function, which likely explained the mild symptoms observed in the patient with the 2810delT mutation. In mammalian cells, exons constitute only a small part of pre-mRNA transcripts. Accurate splicing requires correct NADPH-cytochrome-c2 reductase recognition

of shorter exonic sequences from longer intronic sequences by spliceosomal components that bind an array of intronic and exonic splicing sequence elements. These elements can either enhance (exonic splicing enhancers) or repress (exonic splicing silencers) splicing at a nearby splice site.24, 25 A higher density of exonic splicing enhancers in authentic exons than in pseudoexons may differentiate recognition of the correct exons, whereas the presence of exonic splicing silencers in pseudoexons may suppress their splicing.26, 27 Thus, both these types of elements may contribute to the specificity of pre-mRNA splicing. A web-based splicing regulatory element recognition program28 predicted that the 2810delT mutation increases the number of putative exonic splicing enhancer sites from 1 (TGGTGG) to 4 (GTTGGG, TTGGGG, TGGGGT, and GGGGTA), which may explain the increase in alternatively spliced variants of exon 12 and, consequently, the reduction in disease symptoms.28 Splice-correction therapy modifies or corrects RNA splicing. Most methods that have been reported use antisense oligonucleotide-based compounds that target key elements in pre-mRNA to control splicing in the nucleus.29, 30 For example, this method has been used to correct the alternative splicing of SMN2 pre-mRNA to compensate for a defective SMN1 gene has been used to reduce the severity of spinal muscular atrophy.