5-134606975-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 4P and 1B. PM1 PM2 BP4

The NM_016103.4(SAR1B):c.572G>A(p.Arg191His) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000285 in 1,613,410 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: 𝑓 0.000053 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000026 (0 hom.)
• Consequence: SAR1B NM_016103.4 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.91

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM1: In a chain GTP-binding protein SAR1b (size 197) in uniprot entity SAR1B_HUMAN there are 15 pathogenic changes around while only 1 benign (94%) in NM_016103.4
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.36629778).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SAR1B	NM_016103.4	c.572G>A	p.Arg191His	missense_variant	7/7	ENST00000402673.7
SAR1B	NM_001033503.3	c.572G>A	p.Arg191His	missense_variant	8/8
SAR1B	XM_047417257.1	c.572G>A	p.Arg191His	missense_variant	7/7
SAR1B	XM_047417258.1	c.368G>A	p.Arg123His	missense_variant	5/5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SAR1B	ENST00000402673.7	c.572G>A	p.Arg191His	missense_variant	7/7	1	NM_016103.4	P1

Frequencies

GnomAD3 genomes AF: 0.0000526 AC: 8 AN: 152188 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000724

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000262

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000192

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000103 AC: 26 AN: 251452 Hom.: 0 AF XY: 0.000110 AC XY: 15 AN XY: 135890

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000318

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000326

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000352

Gnomad OTH exome AF: 0.000815

GnomAD4 exome AF: 0.0000260 AC: 38 AN: 1461104 Hom.: 0 Cov.: 30 AF XY: 0.0000275 AC XY: 20 AN XY: 726948

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.000335

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000176

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000117

Gnomad4 OTH exome AF: 0.0000497

GnomAD4 genome AF: 0.0000525 AC: 8 AN: 152306 Hom.: 0 Cov.: 32 AF XY: 0.0000403 AC XY: 3 AN XY: 74480

Gnomad4 AFR AF: 0.0000722

Gnomad4 AMR AF: 0.000262

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000193

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000237 Hom.: 0

Bravo AF: 0.0000529

ESP6500AA AF: 0.00 AC: 0

ESP6500EA AF: 0.000116 AC: 1

ExAC AF: 0.0000494 AC: 6

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Inborn genetic diseases Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 13, 2023

The c.572G>A (p.R191H) alteration is located in exon 8 (coding exon 6) of the SAR1B gene. This alteration results from a G to A substitution at nucleotide position 572, causing the arginine (R) at amino acid position 191 to be replaced by a histidine (H). The in silico prediction for the p.R191H alteration is inconclusive. Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Aug 20, 2021

This sequence change replaces arginine with histidine at codon 191 of the SAR1B protein (p.Arg191His). The arginine residue is highly conserved and there is a small physicochemical difference between arginine and histidine. This variant is present in population databases (rs200409139, ExAC 0.02%). This variant has not been reported in the literature in individuals affected with SAR1B-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0"). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.46
BayesDel_addAF	Benign	-0.035	T
BayesDel_noAF	Uncertain	0.020
Cadd	Uncertain	25
Dann	Uncertain	1.0
DEOGEN2	Benign	0.38	T;.;.;T;.
Eigen	Uncertain	0.43
Eigen_PC	Uncertain	0.46
FATHMM_MKL	Pathogenic	0.98	D
M_CAP	Benign	0.077	D
MetaRNN	Benign	0.37	T;T;T;T;T
MetaSVM	Benign	-0.54	T
MutationAssessor	Uncertain	2.4	M;.;.;M;.
MutationTaster	Benign	1.0	D;D;D;D;D
PrimateAI	Uncertain	0.73	T
PROVEAN	Uncertain	-3.3	D;D;D;D;D
REVEL	Uncertain	0.40
Sift	Uncertain	0.016	D;D;D;D;D
Sift4G	Benign	0.064	T;T;T;T;T
Polyphen		0.72	P;.;.;P;.
Vest4		0.63
MVP		0.82
MPC		0.40
ClinPred		0.22	T
GERP RS		4.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.40
gMVP		0.52

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

Publications

LitVar

Other links and lift over

dbSNP: rs200409139; hg19: chr5-133942665;