5-134607035-C-A

Variant names:

• chr5-134607035-C-A
• rs372284979
• NM_016103.4:c.512G>T

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PM1 PM2 PP2 PP3_Moderate

The NM_016103.4(SAR1B):​c.512G>T​(p.Arg171Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,614 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic 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. R171P) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: SAR1B NM_016103.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 7.91
• Publications: 0 publications found

Genes affected

SAR1B (HGNC:10535): (secretion associated Ras related GTPase 1B) The protein encoded by this gene is a small GTPase that acts as a homodimer. The encoded protein is activated by the guanine nucleotide exchange factor PREB and is involved in protein transport from the endoplasmic reticulum to the Golgi. This protein is part of the COPII coat complex. Defects in this gene are a cause of chylomicron retention disease (CMRD), also known as Anderson disease (ANDD). Two transcript variants encoding the same protein have been found for this gene. [provided by RefSeq, Mar 2010]

SAR1B Gene-Disease associations (from GenCC):

• chylomicron retention disease

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet, PanelApp Australia

ACMG classification

Our verdict: Likely_pathogenic. The variant received 7 ACMG points.

• PM1: In a chain Small COPII coat GTPase SAR1B (size 197) in uniprot entity SAR1B_HUMAN there are 4 pathogenic changes around while only 0 benign (100%) in NM_016103.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 3 curated pathogenic missense variants (we use a threshold of 10). The gene has 0 curated benign missense variants. Gene score misZ: 0.81398 (below the threshold of 3.09). Trascript score misZ: 1.3781 (below the threshold of 3.09). GenCC associations: The gene is linked to chylomicron retention disease.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.898

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_016103.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SAR1B	NM_016103.4	MANE Select	c.512G>T	p.Arg171Leu	missense	Exon 7 of 7	NP_057187.1	Q9Y6B6
	SAR1B	NM_001033503.3		c.512G>T	p.Arg171Leu	missense	Exon 8 of 8	NP_001028675.1	Q9Y6B6

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SAR1B	ENST00000402673.7	TSL:1 MANE Select	c.512G>T	p.Arg171Leu	missense	Exon 7 of 7	ENSP00000385432.2	Q9Y6B6
	SAR1B	ENST00000439578.5	TSL:1	c.512G>T	p.Arg171Leu	missense	Exon 8 of 8	ENSP00000404997.1	Q9Y6B6
	SAR1B	ENST00000507419.5	TSL:1	c.308G>T	p.Arg103Leu	missense	Exon 7 of 7	ENSP00000425339.1	Q9H029

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461614 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 727128

⚠️ 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: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44722

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26130

East Asian (EAS) AF: 0.00 AC: 0 AN: 39692

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86238

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53416

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111788

Other (OTH) AF: 0.00 AC: 0 AN: 60386

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.39	D
BayesDel_noAF	Pathogenic	0.32
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Benign	0.41	T
Eigen	Pathogenic	0.96
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.88	D
M_CAP	Uncertain	0.21	D
MetaRNN	Pathogenic	0.90	D
MetaSVM	Uncertain	0.61	D
MutationAssessor	Pathogenic	4.3	H
PhyloP100		7.9
PrimateAI	Pathogenic	0.81	D
PROVEAN	Pathogenic	-5.9	D
REVEL	Pathogenic	0.74
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0010	D
Polyphen		1.0	D
Vest4		0.78
MutPred		0.76		Loss of disorder (P = 0.1074)
MVP		0.84
MPC		0.89
ClinPred		1.0	D
GERP RS		4.9
Varity_R		0.94
gMVP		0.77
Mutation Taster		=52/48	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.12		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: rs372284979; hg19: chr5-133942725;