Supplementary Figure 4: Cycloheximide results for LCLs from family 3 member FA3b.

(a) Agarose gel of the cDNA PCR product amplified across the germline mutation c.2617−3C>G. Lane 1, cDNA from non-treated LCLs. Lane 2, cDNA from LCLs treated with cycloheximide to inhibit translation. Extra (larger) bands appear as parts of the intron are retained. The part of the intron that is retained is subsequently translated and codes for a premature stop codon, making the transcript subject to nonsense-mediated decay in non-treated cells. (b) Chromatogram showing the part of the intron retained as a result of the mutation. An asterisk denotes the mutation. (c) The amino acids encoded at the end of exon 18 are shown in black, and those encoded by the beginning of the retained intron are shown in red. After 12 amino acids, the intron codes for a stop codon, noted by an asterisk. This subjects the allele to nonsense-mediated decay.