rs748300548

chr19-11110756-C-T

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.1045C>T(p.Gln349Ter) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,224 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★★). Synonymous variant affecting the same amino acid position (i.e. Q349Q) has been classified as Likely benign. Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: LDLR NM_000527.5 stop_gained
• Clinical Significance: Pathogenic reviewed by expert panel P:6 U:1
• Conservation: PhyloP100: 0.428

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 19-11110756-C-T is Pathogenic according to our data. Variant chr19-11110756-C-T is described in ClinVar as [Pathogenic]. Clinvar id is 251611.Status of the report is reviewed_by_expert_panel, 3 stars. Variant chr19-11110756-C-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
LDLR	NM_000527.5	c.1045C>T	p.Gln349Ter	stop_gained	7/18	ENST00000558518.6

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
LDLR	ENST00000558518.6	c.1045C>T	p.Gln349Ter	stop_gained	7/18	1	NM_000527.5	P3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461224 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 726940

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: 0.0000232

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:6 Uncertain:1

Revision: reviewed by expert panel

Submissions by phenotype

Hypercholesterolemia, familial, 1 Pathogenic:5 Uncertain:1

Pathogenic, criteria provided, single submitter	clinical testing	Centre de Génétique Moléculaire et Chromosomique, Unité de génétique de l'Obésité et des Dyslipidémies, APHP, GH Hôpitaux Universitaires Pitié-Salpêtrière / Charles-Foix	Dec 16, 2016	subject mutated among 2600 FH index cases screened = 1 , family member = 1 with co-segregation -
Pathogenic, criteria provided, single submitter	curation	Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard	Jan 22, 2020	The p.Gln349Ter (sometimes called p.Gln328Ter) variant in LDLR has been reported in 3 individuals (including 1 Spanish individual) with Familial Hypercholesterolemia, segregated with disease in 2 affected relatives from 1 family in the literature and ClinVar (PMID: 11668640; Variation ID: 251611), and has been identified in 0.006064% (1/16490) of South Asian chromosomes by the Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.org; dbSNP rs748300548). Although this variant has been seen in the general population, its frequency is low enough to be consistent with a dominant frequency for a disease with clinical variability/reduced penetrance. Please note that for diseases with clinical variability, or reduced penetrance, pathogenic variants may be present at a low frequency in the general population. The number of reported affected individuals with this variant is slightly greater than expected compared to non-affected individuals with this variant. This variant has also been reported as a VUS and a pathogenic variant in ClinVar (Variation ID: 251611). This nonsense variant leads to a premature termination codon at position 349, which is predicted to lead to a truncated or absent protein. Heterozygous loss of function of the LDLR gene is an established disease mechanism in Familial Hypercholesterolemia. In summary, this variant meets criteria to be classified as pathogenic for Familial Hypercholesterolemia in an autosomal dominant manner based on the predicted impact of the variant and multiple occurrences in individuals with Familial Hypercholesterolemia. ACMG/AMP Criteria applied: PVS1, PM2_Supporting, PS4_Supporting (Richards 2015). -
Pathogenic, criteria provided, single submitter	literature only	LDLR-LOVD, British Heart Foundation	Mar 25, 2016	- -
Pathogenic, criteria provided, single submitter	clinical testing	Robarts Research Institute, Western University	Jan 02, 2018	- -
Uncertain significance, criteria provided, single submitter	research	Fundacion Hipercolesterolemia Familiar	Mar 01, 2016	- -
Pathogenic, reviewed by expert panel	curation	ClinGen Familial Hypercholesterolemia Variant Curation Expert Panel	Apr 25, 2022	The NM_000527.5 (LDLR):c.1045C>T (p.Gln349Ter) variant is classified as Pathogenic for Familial Hypercholesterolemia by applying evidence codes (PM2, PVS1, PP4, PS4_Supporting, PM3, PP1_Moderate) as defined by the ClinGen Familial Hypercholesterolemia Expert Panel LDLR-specific variant curation guidelines (https://doi.org/10.1016/j.gim.2021.09.012). The supporting evidence is as follows: PM2: PopMax MAF = 0.00006 in South Asian population in gnomAD (gnomAD v2.1.1). PVS1: The variant causing a premature stop codon amino-terminal of amino acid 830 (NM_000527.5:p.Lys830). PP4: This variant meets PM2 and is identified in >1 index case who met clinical criteria for FH after alternative causes for high cholesterol were excluded. PS4_Supporting: Variant meets PM2, and is identified in 3 unrelated index cases: 1 case fulfil Simon Broome possible FH criteria (Centre de Génétique Moléculaire et Chromosomique, Unité de génétique de l'Obésité et des Dyslipidémies (APHP.Sorbonne Université, Hôpital de la Pitié-Salpêtrière); 1 case fulfil DLCN criteria (Robarts Research Institute, Canada); 1 case met criteria of total and LDL-C levels over the 95th percentile corrected for age and sex, plus two of: tendon xanthomata, premature coronary heart disease in the proband or in a first-degree relative and hypercholesterolemic children in the family (Instituto de Investigaciones Citológicas, Fundación Valenciana de Investigaciones Biomédicas, Valencia, Spain, PMID 11668640). PM3: Variant meets PM2 and is identified in an index case with homozygous FH phenotype (LDL-C: 11.1mmol/l at age of 5 yr.) and is homozygous for the variant (Robarts Research Institute, Canada). PP1_Moderate: Variant segregates with FH phenotype in 4 informative meiosis from 2 families from 2 research labs. One affected relative tested positive for the variant from one family (Centre de Génétique Moléculaire et Chromosomique, Unité de génétique de l'Obésité et des Dyslipidémies APHP.Sorbonne Université, Hôpital de la Pitié-Salpêtrière). Three affected relative tested positive for the variant from another family (Robarts Research Institute, Canada). -

Homozygous familial hypercholesterolemia Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine

Apr 11, 2019

The p.Gln349X variant in LDLR has been reported in 1 individual with familial hypercholesterolemia (FH; Garcia-Garcia 2001) and has also been reported in ClinVar (Variation ID: 251611). It was absent from large population studies. This nonsense variant leads to a premature termination codon at position 349, which is predicted to lead to a truncated or absent protein. Loss of function of the LDLR gene is an established disease mechanism in autosomal dominant FH. In summary, although additional studies are required to fully establish its clinical significance, this variant meets criteria to be classified as likely pathogenic for autosomal dominant FH. ACMG/AMP Criteria applied: PVS1, PM2. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.54
Cadd	Pathogenic	36
Dann	Uncertain	1.0
Eigen	Benign	0.18
Eigen_PC	Benign	-0.10
FATHMM_MKL	Uncertain	0.97	D
MutationTaster	Benign	1.0	A;A;A;A;A;A;A
Vest4		0.93
GERP RS		1.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs748300548; hg19: chr19-11221432;