In 20 apparently unrelated Danish patients with a clinical diagnosis of heterozygous familial hypercholesterolemia (FH), we identified 13 different mutations in the LDL receptor gene: two silent (C331C, N494 N); five missense (W66G, E119K, T383P, W556S, T7051); one nonsense (W23X); three splice-site (313 + 1G-->A, 1061-8T-->C, 1846-1G-->A); and two frameshift (335del10, 1650delG) mutations.