ClinVar

Description

The p.D224N pathogenic mutation (also known as c.670G>A), located in coding exon 4 of the LDLR gene, results from a G to A substitution at nucleotide position 670. The aspartic acid at codon 224 is replaced by asparagine, an amino acid with highly similar properties. This alteration impacts a residue in the conserved cluster of acidic amino acids at the C-terminal end of LDLR class A repeat 5 (Jeon H and Blacklow C. Annu. Rev. Biochem. 2005;74:535-62). This alteration (with legacy nomenclature p.D203N) has been described in the heterozygous and homozygous states in patients with familial hypercholesterolemia (FH), including multiple FH probands from a Portuguese village, three of whom were subsequently shown to be related (Hobbs HH et al. Hum. Mutat., 1992;1:445-66; Wang J et al. J. Lipid Res., 2005 Feb;46:366-72; Blesa S et al. Clin. Chem., 2006 Jun;52:1021-5; Bourbon M et al. Atherosclerosis, 2008 Feb;196:633-42; Gaspar IM et al. Atheroscler Suppl, 2019 Mar;36:28-30). This alteration was also reported in the compound heterozygous state in a patient with severe FH and in a heterozygous state in the proband's affected daughter (Medeiros AM et al. Atherosclerosis, 2010 Oct;212:553-8). This variant is considered to be rare based on population cohorts in the Genome Aggregation Database (gnomAD). Functional studies suggest this alteration causes reduced LDLR activity (Hobbs HH et al. Hum. Mutat., 1992;1:445-66; Deng SJ et al. J. Lipid Res., 2019 Jan;epub ahead of print). Other alterations affecting the same amino acid, p.D224A, p.D224G, and p.D224V, have also been reported in association with FH (Loubser O et al. Clin. Genet., 1999 May;55:340-5; Hobbs HH et al. Hum. Mutat., 1992;1:445-66; Giesel J et al. Hum. Genet., 1995 Sep;96:301-4). Based on the majority of available evidence to date, this variant is interpreted as a disease-causing mutation.