doi: 10.1111/ahg.12032 Novel LDLR Variants in Patients with Familial Hypercholesterolemia: In Silico Analysis as a Tool to Predict Pathogenic Variants in Children and Their Families Vasiliki Mollaki ∗ , Pavlos Progias and Euridiki Drogari 1st Department of Pediatrics, Laboratory of Metabolic Diseases, Choremio Research Laboratory, University of Athens Medical School, “Aghia Sophia” Children’s Hospital, Athens, Greece Summary Familial hypercholesterolemia (FH) is an autosomal dominant disease with a frequency of 1:500 in its heterozygous form. To date, mutations in the low-density lipoprotein receptor gene (LDLR) are the only identified causes of FH in the Greek population, causing high levels of low-density lipoprotein (LDL) and total cholesterol and premature atherosclerosis. The Greek FH population is genetically homogeneous, but most previous studies screened for the most common mutations only. The study aimed to characterize and assess novel LDLR variants. LDLR was examined by whole-gene DNA sequencing in 561 FH patients from 262 families of Greek origin. Novel LDLR variants were analyzed in silico using various software predicting pathogenicity and changes in protein stability. Twelve novel LDLR variants were identified, six of which are putative disease-causing variants: c.977C>G in exon 7, c.1124A>C in exon 8, c.1381G>T in exon 10, c.628_643dup{636del}, c.661–673dup in exon 4, and 13 c.1987+1_+33del in intron 13. All six putative variants were confirmed in the hypercholesterolemic members of the family. The results show that in silico analysis is a valuable tool to predict potential pathogenicity of novel variants, especially for populations that have not been extensively studied. The identification of novel pathogenic variants will facilitate the molecular diagnosis of FH from early childhood. Keywords: Familial hypercholesterolemia (FH), low-density lipoprotein receptor (LDLR), in silico, novel variants, genetics Introduction Familial hypercholesterolemia (FH) is a common autosomal dominant disease with a frequency of 1:500 individuals in its heterozygous form (Soutar & Naoumova 2007). FH pa- tients have high levels of total cholesterol (T–C) and low- density lipoprotein cholesterol (LDL–C) in the plasma and usually present with arcus corneae, xanthelasmas, xanthomas, and premature atherosclerosis, even from childhood (Hobbs et al., 1992). Mutations in the low-density lipoprotein recep- tor (LDLR) (2), apolipoprotein B-100 (apoB-100) (Innerarity et al., 1990), and proprotein convertase subtilisin/kexin type 9 (PCSK9) (Abifadel et al., 2003) have been found to cause FH. ∗ Corresponding author: DR. VASILIKI MOLLAKI, Ph.D., M.Sc., 1st Department of Pediatrics, Laboratory of Metabolic Diseases, Choremio Research Laboratory, University of Athens Medical School, “Aghia Sophia” Children’s Hospital, Thivon and Levadias, Goudi, Athens 11527, Greece. Tel: 0030 210 7467482; Fax: 0030 210 7795762; E-mail: vmollaki@med.uoa.gr The clinical phenotype of FH patients is variable. There are three sets of criteria used for the clinical diagnosis of FH. These are the Simon Broome Register (UK), the Dutch Lipid Clinic Network (Netherlands), and the MEDPED Program (USA) criteria. However, although these criteria have been proven to be useful in identifying adult FH patients, they rely mainly on detection of clinical signs of heterozygous FH (xanthelasma, tendinous xanthomata, and corneal arcus) or manifestations of coronary heart disease, which occur in adulthood. Such clinical signs are rarely present in affected children or even in their young parents and therefore the clinical diagnosis may miss a considerable proportion of FH pediatric patients in whom the phenotype is not apparent yet. In addition, a proportion of children at high risk for FH, even carriers of mutations causing FH, may initially present lipid levels within the normal range and later develop hyper- cholesterolemia consistent with the diagnosis of FH (Kessling et al., 1990). Therefore, lipid levels within the normal range for childhood do not necessarily exclude FH. The presence Annals of Human Genetics (2013) 1 C  2013 John Wiley & Sons Ltd/University College London