22-28797147-A-C

Position:

• chr22-28797147-A-C

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_001079539.2(XBP1):​c.383T>G​(p.Val128Gly) 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. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency: Genomes: not found (cov: 32)
• Consequence: XBP1 NM_001079539.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.56

Genes affected

XBP1 (HGNC:12801): (X-box binding protein 1) This gene encodes a transcription factor that regulates MHC class II genes by binding to a promoter element referred to as an X box. This gene product is a bZIP protein, which was also identified as a cellular transcription factor that binds to an enhancer in the promoter of the T cell leukemia virus type 1 promoter. It may increase expression of viral proteins by acting as the DNA binding partner of a viral transactivator. It has been found that upon accumulation of unfolded proteins in the endoplasmic reticulum (ER), the mRNA of this gene is processed to an active form by an unconventional splicing mechanism that is mediated by the endonuclease inositol-requiring enzyme 1 (IRE1). The resulting loss of 26 nt from the spliced mRNA causes a frame-shift and an isoform XBP1(S), which is the functionally active transcription factor. The isoform encoded by the unspliced mRNA, XBP1(U), is constitutively expressed, and thought to function as a negative feedback regulator of XBP1(S), which shuts off transcription of target genes during the recovery phase of ER stress. A pseudogene of XBP1 has been identified and localized to chromosome 5. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

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

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
XBP1	NM_001079539.2	c.383T>G	p.Val128Gly	missense_variant	3/6		NP_001073007.1
XBP1	NM_001393999.1	c.233T>G	p.Val78Gly	missense_variant	3/6		NP_001380928.1
XBP1	NM_005080.4	c.383T>G	p.Val128Gly	missense_variant	3/5		NP_005071.2
XBP1	NM_001394000.1	c.233T>G	p.Val78Gly	missense_variant	3/5		NP_001380929.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
XBP1	ENST00000344347.6	c.383T>G	p.Val128Gly	missense_variant	3/6	5		ENSP00000343155.5
XBP1	ENST00000216037.10	c.383T>G	p.Val128Gly	missense_variant	3/5	1		ENSP00000216037.6
XBP1	ENST00000403532.7	c.398T>G	p.Val133Gly	missense_variant	3/5	3		ENSP00000385162.3
XBP1	ENST00000405219.7	c.233T>G	p.Val78Gly	missense_variant	3/5	2		ENSP00000384295.3

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Dec 10, 2024

The c.383T>G (p.V128G) alteration is located in exon 3 (coding exon 3) of the XBP1 gene. This alteration results from a T to G substitution at nucleotide position 383, causing the valine (V) at amino acid position 128 to be replaced by a glycine (G). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.15
BayesDel_addAF	Benign	-0.021	T
BayesDel_noAF	Benign	-0.27
CADD	Uncertain	25
DANN	Benign	0.95
DEOGEN2	Benign	0.23	T;T;.;T;.
Eigen	Benign	0.13
Eigen_PC	Uncertain	0.28
FATHMM_MKL	Uncertain	0.86	D
LIST_S2	Benign	0.65	T;T;T;T;.
M_CAP	Benign	0.0049	T
MetaRNN	Benign	0.16	T;T;T;T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	1.3	L;.;L;.;L
PrimateAI	Benign	0.27	T
PROVEAN	Benign	-1.9	N;N;.;D;N
REVEL	Benign	0.087
Sift	Benign	0.34	T;T;.;T;T
Sift4G	Benign	0.37	T;T;T;T;T
Polyphen		0.35, 0.63	.;.;B;P;B
Vest4		0.23
MutPred		0.29		.;.;.;Loss of sheet (P = 0.0104);.;
MVP		0.34
MPC		0.49
ClinPred		0.33	T
GERP RS		5.9
Varity_R		0.12
gMVP		0.55

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.45		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.45		Position offset: 0

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr22-29193135;