rs760014795

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong

The NM_000370.3(TTPA):c.19del(p.Gln7SerfsTer64) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000874 in 1,486,838 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. Q7Q) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 33)

Exomes 𝑓: 0.0000082 ( 0 hom. )

Consequence

TTPA
NM_000370.3 frameshift

Scores

Not classified

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3

Conservation

PhyloP100: 0.518

Variant links:

Genes affected

TTPA (HGNC:12404): (alpha tocopherol transfer protein) This gene encodes a soluble protein that binds alpha-trocopherol, a form of vitamin E, with high selectivity and affinity. This protein plays an important role in regulating vitamin E levels in the body by transporting vitamin E between membrane vesicles and facilitating the secretion of vitamin E from hepatocytes to circulating lipoproteins. Mutations in this gene cause hereditary vitamin E deficiency (ataxia with vitamin E deficiency, AVED) and retinitis pigmentosa. [provided by RefSeq, Nov 2009]

TTPA links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 18 ACMG points.

PVS1

Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 45 pathogenic variants in the truncated region.

PM2

Very rare variant in population databases, with high coverage;

PP5

Variant 8-63086002-TG-T is Pathogenic according to our data. Variant chr8-63086002-TG-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 208623.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTPA	NM_000370.3 linkuse as main transcript	c.19del	p.Gln7SerfsTer64	frameshift_variant	1/5	ENST00000260116.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTPA	ENST00000260116.5 linkuse as main transcript	c.19del	p.Gln7SerfsTer64	frameshift_variant	1/5	1	NM_000370.3	P1
TTPA	ENST00000521138.1 linkuse as main transcript	n.47del		non_coding_transcript_exon_variant	1/2	5

Frequencies

GnomAD3 genomes

AF:

0.0000132

AC:

AN:

151934

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.000288

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000481

AC:

AN:

104000

Hom.:

AF XY:

0.0000503

AC XY:

AN XY:

59688

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.000762

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000824

AC:

AN:

1334904

Hom.:

Cov.:

AF XY:

0.0000106

AC XY:

AN XY:

659902

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.000349

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00

Gnomad4 OTH exome

AF:

0.0000546

GnomAD4 genome

AF:

0.0000132

AC:

AN:

151934

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74226

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.000288

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000147

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000843

Hom.:

Bravo

AF:

0.00000378

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Familial isolated deficiency of vitamin E

Pathogenic:2

Pathogenic, criteria provided, single submitter	clinical testing	Laboratory for Molecular Medicine, Mass General Brigham Personalized Medicine	Dec 22, 2014	The p.Gln7SerfsX64 variant in TTPA has not been previously reported in individuals with disease but has been identified in 0.016% (1/6134) of European chromosomes by the Exome Aggregation Consortium (ExAC, http://exac.broadinstitute.org). Although this variant has been seen in the general population, its frequency is low enough to be consistent with a recessive carrier frequency. This variant is predicted to cause a frameshift, which alters the protein’s amino acid sequence beginning at position 7 and leads to a premature termination codon 64 amino acids downstream. This alteration is then predicted to lead to a truncated or absent protein. Homozygous or compound heterozygous loss of function variants in TTPA have been shown to cause ataxia with isolated vitamin E deficiency. In summary, this variant meets our criteria to be classified as pathogenic for ataxia with isolated vitamin E deficiency in an autosomal recessive manner. -
Likely pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	May 26, 2023	- -

not provided

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Oct 28, 2023

This sequence change creates a premature translational stop signal (p.Gln7Serfs*64) in the TTPA gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in TTPA are known to be pathogenic (PMID: 9463307, 26068213). This variant is present in population databases (rs760014795, gnomAD 0.09%). This variant has not been reported in the literature in individuals affected with TTPA-related conditions. ClinVar contains an entry for this variant (Variation ID: 208623). For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over