Minigenes containing genomic LDLR exons 9−14 were cloned from two rs688C/C individuals and two rs688T/T individuals. One clone from each person was transfected into HepG2 cells and splicing patterns analyzed in triplicate beginning with cell transfections. The two rs688C genotype clones were associated with a higher splicing efficiency, i.e., 56 ±3.8 and 53.4±0.4 (%, mean ±SD, triplicate analysis) than the two rs699T genotype clones, i.e., 42.6± 0.8 and 40.4±1.3. Similar results were observed in two separate experiments. Hence, relative differences in splicing efficiency in vivo are replicated in vitro.