19-7644720-G-C

Variant summary

Our verdict is Pathogenic. Variant got 10 ACMG points: 10P and 0B. PM1 PM2 PM5 PP3_Strong

The NM_006949.4(STXBP2):c.1214G>C(p.Arg405Pro) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R405Q) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 33)
• Consequence: STXBP2 NM_006949.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.82

Genes affected

STXBP2 (HGNC:11445): (syntaxin binding protein 2) This gene encodes a member of the STXBP/unc-18/SEC1 family. The encoded protein is involved in intracellular trafficking, control of SNARE (soluble NSF attachment protein receptor) complex assembly, and the release of cytotoxic granules by natural killer cells. Mutations in this gene are associated with familial hemophagocytic lymphohistiocytosis. Alternatively spliced transcript variants encoding different isoforms have been noted for this gene. [provided by RefSeq, Jan 2013]

ACMG classification

Verdict is Pathogenic. Variant got 10 ACMG points.

• PM1: In a helix (size 14) in uniprot entity STXB2_HUMAN there are 4 pathogenic changes around while only 0 benign (100%) in NM_006949.4
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr19-7644720-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 538148.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.984

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
STXBP2	NM_006949.4	c.1214G>C	p.Arg405Pro	missense_variant	14/19	ENST00000221283.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
STXBP2	ENST00000221283.10	c.1214G>C	p.Arg405Pro	missense_variant	14/19	1	NM_006949.4	P4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 33

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Familial hemophagocytic lymphohistiocytosis 5 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jan 26, 2022

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. This variant disrupts the p.Arg405 amino acid residue in STXBP2. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 19804848, 20558610, 20798128, 23382066, 24194549, 28353193, 30697212). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. Experimental studies have shown that this missense change affects STXBP2 function (PMID: 10788461). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. This variant has not been reported in the literature in individuals affected with STXBP2-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with proline, which is neutral and non-polar, at codon 405 of the STXBP2 protein (p.Arg405Pro). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.48	D
BayesDel_noAF	Pathogenic	0.46
Cadd	Pathogenic	31
Dann	Uncertain	0.99
Eigen	Uncertain	0.39
Eigen_PC	Benign	0.21
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Pathogenic	0.99	D;D;D
M_CAP	Uncertain	0.26	D
MetaRNN	Pathogenic	0.98	D;D;D
MetaSVM	Uncertain	0.70	D
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.72	T
PROVEAN	Pathogenic	-6.9	D;D;D
REVEL	Pathogenic	0.77
Sift	Uncertain	0.0010	D;D;D
Sift4G	Pathogenic	0.0010	D;D;D
Polyphen		1.0	.;D;D
Vest4		0.95
MutPred		0.91		.;Gain of catalytic residue at R405 (P = 0.0515);.;
MVP		0.97
MPC		1.1
ClinPred		1.0	D
GERP RS		1.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.99
gMVP		0.98

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: rs773360200; hg19: chr19-7709606;