chr6-33304170-C-T

Position:

• chr6-33304170-C-T

Variant summary

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

The NM_003190.5(TAPBP):​c.1258G>A​(p.Ala420Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000041 in 1,461,812 control chromosomes in the GnomAD database, with no homozygous occurrence. 11/19 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: TAPBP NM_003190.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.61

Genes affected

TAPBP (HGNC:11566): (TAP binding protein) This gene encodes a transmembrane glycoprotein which mediates interaction between newly assembled major histocompatibility complex (MHC) class I molecules and the transporter associated with antigen processing (TAP), which is required for the transport of antigenic peptides across the endoplasmic reticulum membrane. This interaction is essential for optimal peptide loading on the MHC class I molecule. Up to four complexes of MHC class I and this protein may be bound to a single TAP molecule. This protein contains a C-terminal double-lysine motif (KKKAE) known to maintain membrane proteins in the endoplasmic reticulum. This gene lies within the major histocompatibility complex on chromosome 6. Alternative splicing results in three transcript variants encoding different isoforms. [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	UniProt
TAPBP	NM_003190.5	c.1258G>A	p.Ala420Thr	missense_variant	6/8	ENST00000434618.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TAPBP	ENST00000434618.7	c.1258G>A	p.Ala420Thr	missense_variant	6/8	1	NM_003190.5	P2

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 0.00000410 AC: 6 AN: 1461812 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727210

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000540

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

MHC class I deficiency Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Sep 02, 2021

This variant has not been reported in the literature in individuals affected with TAPBP-related conditions. 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. 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: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). This variant is not present in population databases (ExAC no frequency). This sequence change replaces alanine with threonine at codon 420 of the TAPBP protein (p.Ala420Thr). The alanine residue is highly conserved and there is a small physicochemical difference between alanine and threonine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.15
BayesDel_addAF	Benign	-0.065	T
BayesDel_noAF	Benign	-0.33
CADD	Benign	21
DANN	Uncertain	0.99
DEOGEN2	Benign	0.068	.;T;.;T
Eigen	Benign	0.012
Eigen_PC	Benign	-0.0058
FATHMM_MKL	Uncertain	0.78	D
LIST_S2	Uncertain	0.90	D;D;D;D
M_CAP	Benign	0.032	D
MetaRNN	Uncertain	0.55	D;D;D;D
MetaSVM	Benign	-0.80	T
MutationTaster	Benign	1.0	D;D;D;D;D
PrimateAI	Uncertain	0.52	T
PROVEAN	Benign	-2.3	N;N;N;N
REVEL	Benign	0.21
Sift	Pathogenic	0.0	D;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D
Polyphen		0.79	.;P;.;.
Vest4		0.55
MutPred		0.47		.;Gain of sheet (P = 0.0827);.;.;
MVP		0.56
MPC		0.79
ClinPred		0.97	D
GERP RS		4.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
gMVP		0.44

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs1382572674; hg19: chr6-33271947;