A mutation (-49C>T) in the promoter of the low density lipoprotein receptor gene associated with familial hypercholesterolemia

<p><span lang="EN-US">We<span> </span>have<span> </span>identified<span> </span>a<span> </span>mutation<span> </span>(-49C>T)<span> </span>in<span> </span>the <span>low-density lipoprotein receptor (LDLR) gene in a Spanish </span><span>familial hypercholesterolemia (FH) patient. The mutation </span>maps<span> </span>within<span> </span>repeat<span> </span>3<span> </span>of<span> </span>the<span> </span>LDLR<span> </span>gene<span> </span>promoter.<span> </span>This<span> </span>re<span>gion</span><span> </span><span>binds</span><span> </span><span>Sp1</span><span> </span><span>and</span><span> </span><span>collaborates</span><span> </span><span>with</span><span> </span><span>repeat</span><span> </span><span>2</span><span> </span><span>in</span><span> </span><span>the</span><span> </span><span>regula</span><span>tion</span><span> </span><span>of</span><span> </span><span>LDLR</span><span> </span><span>gene</span><span> </span><span>by</span><span> </span><span>sterols.</span><span> </span><span>To</span><span> </span><span>evaluate</span><span> </span><span>whether</span><span> </span><span>the</span><span> mu</span>tation influenced the activity of the promoter, luciferase reporter<span> </span>plasmids<span> </span>containing<span> </span>296<span> </span>bp<span> </span>of<span> </span>the<span> </span>proximal<span> </span>pro<span>moter region were constructed. In transient transfection as-says</span><span> </span><span>in</span><span> </span><span>HepG2</span><span> </span><span>cells,</span><span> </span><span>the</span><span> </span><span>mutation</span><span> </span><span>resulted</span><span> </span><span>in</span><span> </span><span>an</span><span> </span><span>80%</span><span> </span><span>reduc</span><span>tion of promoter activity. Also, gel-shift assays demonstrated </span>that<span> </span>the<span> </span>mutation<span> </span>severely<span> </span>affects<span> </span>Sp1<span> </span>binding.<span> </span>However, <span>the</span><span> </span><span>mutated</span><span> </span><span>promoter</span><span> </span><span>still</span><span> </span><span>retains</span><span> </span><span>the</span><span> </span><span>ability</span><span> </span><span>to</span><span> </span><span>respond</span><span> </span><span>to </span>low sterol concentrations. As the analysis of the LDLR gene did not reveal any other changes, we conclude that <span>the</span><span> </span><span>-49C>T</span><span> </span><span>mutation</span><span> </span><span>is</span><span> </span><span>the</span><span> </span><span>cause</span><span> </span><span>of</span><span> </span><span>FH</span><span> </span><span>in</span><span> </span><span>the</span><span> </span><span>patient.</span><span> </span><span>The </span>analysis<span> </span>of<span> </span>the<span> </span>proband’s<span> </span>pedigree<span> </span>indicated<span> </span>that<span> </span>not<span> </span><span>all</span> the<span> </span>members<span> </span>of<span> </span>the<span> </span>family<span> </span>having<span> </span>the<span> </span>mutation<span> </span>disclose<span> </span>a <span>FH</span> <span>phenotype. These</span><span> </span><span>results</span><span> </span><span>support</span><span> </span><span>the</span><span> </span><span>view</span><span> </span><span>that</span><span> </span><span>factors </span><span>other</span><span> </span><span>than</span><span> </span><span>the</span><span> </span><span>presence</span><span> </span><span>of</span><span> </span><span>the</span><span> </span><span>mutation</span><span> </span><span>are</span><span> </span><span>important</span><span> </span><span>in</span><span> </span><span>the </span><span>determination of the clinical phenotype in FH.</span></span></p>