6-33304160-A-G

Position:

• chr6-33304160-A-G

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_003190.5(TAPBP):​c.1268T>C​(p.Leu423Pro) variant causes a missense change. The variant allele was found at a frequency of 0.00000137 in 1,461,824 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: TAPBP NM_003190.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 4.84

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 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.872

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TAPBP	NM_003190.5	c.1268T>C	p.Leu423Pro	missense_variant	6/8	ENST00000434618.7	NP_003181.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TAPBP	ENST00000434618.7	c.1268T>C	p.Leu423Pro	missense_variant	6/8	1	NM_003190.5	ENSP00000395701	P2

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461824 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727214

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: 8.99e-7

Gnomad4 OTH exome AF: 0.0000166

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

Jan 31, 2020

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 (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with TAPBP-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces leucine with proline at codon 423 of the TAPBP protein (p.Leu423Pro). The leucine residue is highly conserved and there is a moderate physicochemical difference between leucine and proline. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.54
BayesDel_addAF	Uncertain	0.14	D
BayesDel_noAF	Uncertain	-0.030
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Benign	0.32	.;T;.;T
Eigen	Uncertain	0.50
Eigen_PC	Uncertain	0.43
FATHMM_MKL	Uncertain	0.88	D
LIST_S2	Benign	0.81	T;T;T;T
M_CAP	Uncertain	0.19	D
MetaRNN	Pathogenic	0.87	D;D;D;D
MetaSVM	Benign	-0.49	T
MutationTaster	Benign	1.0	D;D;D;D;D
PrimateAI	Uncertain	0.56	T
PROVEAN	Uncertain	-4.2	D;D;D;D
REVEL	Uncertain	0.35
Sift	Uncertain	0.0010	D;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D
Polyphen		0.98	.;D;.;.
Vest4		0.80
MutPred		0.67		.;Gain of sheet (P = 0.0101);.;.;
MVP		0.80
MPC		1.4
ClinPred		0.99	D
GERP RS		5.4
gMVP		0.88

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: rs1768780166; hg19: chr6-33271937;