chr2-21032508-G-T

Variant names:

• chr2-21032508-G-T
• rs778866803
• NM_000384.3:c.1198C>A

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_000384.3(APOB):​c.1198C>A​(p.Arg400Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 16/20 in silico tools predict a benign outcome for this variant. 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. R400H) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: APOB NM_000384.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 2.98
• Publications: 5 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: Likely_benign. The variant received -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.049235076).

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.1198C>A	p.Arg400Ser	missense	Exon 10 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.1198C>A	p.Arg400Ser	missense	Exon 10 of 29	ENSP00000233242.1
	APOB	ENST00000399256.4	TSL:1	c.1198C>A	p.Arg400Ser	missense	Exon 10 of 17	ENSP00000382200.4
	APOB	ENST00000673739.2		n.*504C>A		non_coding_transcript_exon	Exon 9 of 25	ENSP00000501110.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.078
BayesDel_addAF	Benign	-0.24	T
BayesDel_noAF	Benign	-0.58
CADD	Benign	7.5
DANN	Benign	0.47
DEOGEN2	Benign	0.0091	T
Eigen	Benign	-1.5
Eigen_PC	Benign	-1.4
FATHMM_MKL	Benign	0.051	N
LIST_S2	Benign	0.44	T
M_CAP	Benign	0.019	T
MetaRNN	Benign	0.049	T
MetaSVM	Benign	-1.0	T
PhyloP100		3.0
PrimateAI	Benign	0.26	T
PROVEAN	Benign	1.2	N
REVEL	Benign	0.14
Sift	Benign	0.55	T
Sift4G	Benign	0.30	T
Vest4		0.15
MutPred		0.53		Loss of catalytic residue at R400 (P = 0.0469)
MVP		0.44
MPC		0.040
ClinPred		0.035	T
GERP RS		-1.3
gMVP		0.11
Mutation Taster		=78/22	polymorphism

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: rs778866803; hg19: chr2-21255380;