DNA screening for low-density lipoprotein (LDL) receptor mutations was performed in a clinically diagnosed six-year-old familial hypercholesterolemia (FH) patient. The promoter region and the coding sequence of the LDL receptor gene were amplified by means of polymerase chain reaction and subjected to DNA sequencing to study the molecular lesion. A G→A transition in codon 207, changing Glu207 to Lys (E207K) in the ligand-binding domain of the LDL receptor, was identified. Analysis with MnlI endonuclease digestion showed this mutation to be inherited from paternal grandmother. The proband's two siblings also carried the mutation. Identification of the disease-causing mutation can clearly define the cause of patient's hyperlipidemia and allow appropriate early treatment and antenatal and family studies.