Mutation analysis. (A-E) Sequence traces showing the splicing site mutation of human microphthalmia-associated transcription factor (MITF)-M. (A&B) Sequence of exon 2 of wild-type MITF-M using the forward primer. (C) Sequence of exon 6 of wild-type MITF-M using the reverse primer. (D) Sequence of exon 2 of the MITF-Mdel using the forward primer. (E) Sequence of exon 6 of the MITF-Mdel using the reverse primer. The nucleotides between the underlined nucleotides indicate the deletion regions. (F) Schematic representation of the structures of MITF-M and MITF-Mdel. The MITF-Mdel isoform has a 168-bp in-frame deletion in exon 2 and an 18-bp in-frame deletion in exon 6, but still has the transcriptional activation domain, the b-HLH-LZ domain and the serine-rich region (S).