We used polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis to detect a mutation in the low density lipoprotein receptor (LDLR) gene in a family of Iranian-Armenian origin. The mutation, designated FH Yrmeih, deletes two nucleotides from exon 10 of the LDLR gene, which causes a translational frameshift, whereby a truncated LDLR protein of the first 471 residues of the LDLR with an additional 41 abnormal residues and a premature stop codon would be created. The deletion was detected in a father and son with clinical features of heterozygous FH. To our knowledge this is the first pathogenetic LDLR mutation identified in FH patients of Iranian-Armenian ancestry.