Figure 4: Nucleotide sequence at the exon 4-intron 4 junction showing the most prevalent mutation c.400+2dup. T insertion between nucleotides 1831-1832 or 1832- 1833 at the IVS4 splice donor site (A) results in deletion of exon 4 in mRNA, leading to a premature termination at amino acid 110 (Ala108Glufs*3) (B) (adapted from 1 and 17).