rs747344293

chr19-11129597-AC-Achr19-11129597-AC-ACC

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000527.5(LDLR):c.2478del(p.Val827SerfsTer102) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,848 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: LDLR NM_000527.5 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: -0.0920

Genes affected

LDLR (HGNC:6547): (low density lipoprotein receptor) The low density lipoprotein receptor (LDLR) gene family consists of cell surface proteins involved in receptor-mediated endocytosis of specific ligands. The encoded protein is normally bound at the cell membrane, where it binds low density lipoprotein/cholesterol and is taken into the cell. Lysosomes release the cholesterol, which is made available for repression of microsomal enzyme 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase, the rate-limiting step in cholesterol synthesis. At the same time, a reciprocal stimulation of cholesterol ester synthesis takes place. Mutations in this gene cause the autosomal dominant disorder, familial hypercholesterolemia. Alternate splicing results in multiple transcript variants.[provided by RefSeq, May 2022]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 19-11129597-AC-A is Pathogenic according to our data. Variant chr19-11129597-AC-A is described in ClinVar as [Pathogenic]. Clinvar id is 252342.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr19-11129597-AC-A is described in Lovd as [Pathogenic]. Variant chr19-11129597-AC-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
LDLR	NM_000527.5	c.2478del	p.Val827SerfsTer102	frameshift_variant	17/18	ENST00000558518.6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
LDLR	ENST00000558518.6	c.2478del	p.Val827SerfsTer102	frameshift_variant	17/18	1	NM_000527.5	P3

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461848 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727222

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Hypercholesterolemia, familial, 1 Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Robarts Research Institute, Western University	Jan 02, 2018	- -
Pathogenic, criteria provided, single submitter	literature only	LDLR-LOVD, British Heart Foundation	Mar 25, 2016	- -
Pathogenic, criteria provided, single submitter	curation;literature only	Cardiovascular Research Group, Instituto Nacional de Saude Doutor Ricardo Jorge	Mar 01, 2016	- -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

GeneDx

Feb 23, 2018

The c.2478delC pathogenic variant in the LDLR gene was paternally inherited in a Chinese child with severe familial hypercholesterolemia and a second maternally inherited variant in the LDLR gene; of note, the heterozygous father was reported to have elevated cholesterol (Sun et al., 1994). This variant causes a shift in reading frame starting at codon valine (Val) 827, changing it to a serine (Ser), and creating a premature stop codon at position 102 of the new reading frame, denoted p.Val827SerfsX102. This pathogenic variant is located in the penultimate exon and is predicted to result in an abnormal protein product with the last 34 amino acid residues replaced by 101 incorrect amino acid residues. Functional studies show that the c.2478delC variant results in either no detectable LDLR protein, or low levels of LDLR protein that is unable to bind the LDL ligand (Sun et al., 1994). Other frameshift variants in the LDLR gene have been reported in Human Gene Mutation Database in association with FH (Stenson et al., 2014), including a different downstream frameshift variant (c.2509delC) predicted to use the same termination codon as the c.2478delC variant. Furthermore, the c.2478delC variant has not been observed in large population cohorts (Lek et al., 2016). -

Cardiovascular phenotype Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Oct 12, 2023

The c.2478delC (p.V827Sfs*102) alteration, located in exon 17 (coding exon 17) of the LDLR gene, consists of a deletion of one nucleotide at position 2478, causing a translational frameshift with a predicted alternate stop codon after 102 amino acids. This alteration occurs at the 3' terminus of theLDLR gene, is not expected to trigger nonsense-mediated mRNAdecay and results in the elongation of the protein by 67 amino acids. This frameshift impacts the last 34 amino acids(~4%) of the native protein. However, frameshifts are typically deleterious in nature and the impacted region is critical for protein function (Ambry internal data). This variant was not reported in population-based cohorts in the Genome Aggregation Database (gnomAD). This alteration, referred to as a 1-bp deletion in codon 805, was reported in a family with familial hypercholesterolemia and in vitro studies suggested that it would affect LDLR protein expression or stability (Sun, 1994). Based on the available evidence, this alteration is classified as pathogenic. -

Familial hypercholesterolemia Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Nov 04, 2022

For these reasons, this variant has been classified as Pathogenic. This variant disrupts a region of the LDLR protein in which other variant(s) (p.Ser849*) have been determined to be pathogenic (PMID: 2088165, 11933210, 22509010, 26892515). This suggests that this is a clinically significant region of the protein, and that variants that disrupt it are likely to be disease-causing. Experimental studies have shown that this premature translational stop signal affects LDLR function (PMID: 7903864). Algorithms developed to predict the effect of variants on protein structure and function are not available or were not evaluated for this variant. ClinVar contains an entry for this variant (Variation ID: 252342). This premature translational stop signal has been observed in individual(s) with hypercholesterolemia (PMID: 7903864). This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Val827Serfs*102) in the LDLR gene. While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 34 amino acid(s) of the LDLR protein. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs747344293; hg19: chr19-11240273;