NM_000384.3:c.889C>A

Variant names:

• chr2-21034831-G-T
• rs766376456
• NM_000384.3:c.889C>A

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PM2

The NM_000384.3(APOB):​c.889C>A​(p.Arg297Ser) variant causes a missense change. The variant allele was found at a frequency of 0.00000188 in 1,592,828 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R297H) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: APOB NM_000384.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 4.07
• Publications: 3 publications found

Genes affected

APOB (HGNC:603): (apolipoprotein B) This gene product is the main apolipoprotein of chylomicrons and low density lipoproteins (LDL), and is the ligand for the LDL receptor. It occurs in plasma as two main isoforms, apoB-48 and apoB-100: the former is synthesized exclusively in the gut and the latter in the liver. The intestinal and the hepatic forms of apoB are encoded by a single gene from a single, very long mRNA. The two isoforms share a common N-terminal sequence. The shorter apoB-48 protein is produced after RNA editing of the apoB-100 transcript at residue 2180 (CAA->UAA), resulting in the creation of a stop codon, and early translation termination. Mutations in this gene or its regulatory region cause hypobetalipoproteinemia, normotriglyceridemic hypobetalipoproteinemia, and hypercholesterolemia due to ligand-defective apoB, diseases affecting plasma cholesterol and apoB levels. [provided by RefSeq, Dec 2019]

APOB Gene-Disease associations (from GenCC):

• hypercholesterolemia, autosomal dominant, type B

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Genomics England PanelApp, G2P, Labcorp Genetics (formerly Invitae), ClinGen, Ambry Genetics
• familial hypobetalipoproteinemia 1

  Inheritance: AR, AD, SD Classification: DEFINITIVE, STRONG Submitted by: PanelApp Australia, Labcorp Genetics (formerly Invitae), Genomics England PanelApp, ClinGen
• homozygous familial hypercholesterolemia

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000384.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	APOB	NM_000384.3	MANE Select	c.889C>A	p.Arg297Ser	missense	Exon 8 of 29	NP_000375.3

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	APOB	ENST00000233242.5	TSL:1 MANE Select	c.889C>A	p.Arg297Ser	missense	Exon 8 of 29	ENSP00000233242.1
	APOB	ENST00000399256.4	TSL:1	c.889C>A	p.Arg297Ser	missense	Exon 8 of 17	ENSP00000382200.4
	APOB	ENST00000673739.2		n.*195C>A		non_coding_transcript_exon	Exon 7 of 25	ENSP00000501110.2

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152170 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000139 AC: 2 AN: 1440658 Hom.: 0 Cov.: 27 AF XY: 0.00000279 AC XY: 2 AN XY: 718118

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33072

American (AMR) AF: 0.00 AC: 0 AN: 44704

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26014

East Asian (EAS) AF: 0.00 AC: 0 AN: 39600

South Asian (SAS) AF: 0.0000117 AC: 1 AN: 85810

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53408

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5732

European-Non Finnish (NFE) AF: 9.15e-7 AC: 1 AN: 1092694

Other (OTH) AF: 0.00 AC: 0 AN: 59624

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.0448430), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152170 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74336

African (AFR) AF: 0.00 AC: 0 AN: 41428

American (AMR) AF: 0.00 AC: 0 AN: 15280

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5196

South Asian (SAS) AF: 0.00 AC: 0 AN: 4826

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10616

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68034

Other (OTH) AF: 0.00 AC: 0 AN: 2094

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.71
BayesDel_addAF	Uncertain	0.095	D
BayesDel_noAF	Benign	-0.10
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Benign	0.15	T
Eigen	Uncertain	0.61
Eigen_PC	Uncertain	0.54
FATHMM_MKL	Benign	0.69	D
LIST_S2	Uncertain	0.86	D
M_CAP	Benign	0.071	D
MetaRNN	Uncertain	0.46	T
MetaSVM	Benign	-0.58	T
PhyloP100		4.1
PrimateAI	Benign	0.32	T
PROVEAN	Uncertain	-3.8	D
REVEL	Benign	0.28
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Vest4		0.43
MutPred		0.58		Loss of catalytic residue at R297 (P = 0.0174)
MVP		0.70
MPC		0.18
ClinPred		0.99	D
GERP RS		3.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.0
gMVP		0.57
Mutation Taster		=27/73	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs766376456; hg19: chr2-21257703;