Figure 1. The use of a cryptic 5′ splice site (5′SS) is at the origin of the Hutchison–Gilford progeria syndrome (HGPS). (a) In normal individuals, a distal 5′SS is used in exon 11 of the LMNA gene. The encoded mRNA will be translated into prelamin A, which will undergo four steps of post‐translational maturation. Mature lamin A is a component of the nuclear envelope; (b) In HGPS patients, there is an activation of a cryptic splice site in exon 11 of the LMNA gene. The use of this cryptic splice site leads to the deletion of 150 nt, thus 50 amino acids, from prelamin A. This truncated prelamin A will undergo anincomplete maturation, remain farnesylated, and aggregate in the nuclear periphery. The nuclear abnormalities that are caused by the truncated protein, progerin, are responsible for progeria.

Figure 2. A quick protocol for splicing reporter transfection. (a) Prepare two solutions, one containing plasmid DNA and one containing DreamFect reagent (never vortex DreamFect!); (b) Combine the two solutions carefully: dropwise addition, mixing by gently pippetting up and down; (C) Add the solution to the cells with freshly replaced medium. Rock the tissue culture plate to homogenize; (d) Incubate the cells at 37 °C in a CO ₂ incubator, and evaluate splicing of the reporter.

Figure 3. Anticipated results. (a) When transiently transfected in HeLa cells, the wild‐type (WT) βglo‐LMNA splicing reporter produces only the full‐length splicing isoform; (b) On the other hand, the 1824C → T βglo‐LMNA reporter shows a very important use of the cryptic splice site, as verified by agarose gel analysis of the RT‐PCR products.