rs756313678

Positions:

chr8-63061337-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM1PM2

The NM_000370.3(TTPA):c.752C>T(p.Ser251Phe) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000155 in 1,613,758 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★).

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000016 ( 0 hom. )

Consequence

TTPA
NM_000370.3 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:6

Conservation

PhyloP100: 2.92

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 Uncertain_significance. Variant got 4 ACMG points.

PM1

In a chain Alpha-tocopherol transfer protein (size 277) in uniprot entity TTPA_HUMAN there are 5 pathogenic changes around while only 1 benign (83%) in NM_000370.3

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TTPA	NM_000370.3 linkuse as main transcript	c.752C>T	p.Ser251Phe	missense_variant	5/5	ENST00000260116.5	NP_000361.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TTPA	ENST00000260116.5 linkuse as main transcript	c.752C>T	p.Ser251Phe	missense_variant	5/5	1	NM_000370.3	ENSP00000260116	P1
TTPA	ENST00000521138.1 linkuse as main transcript	n.233-12734C>T		intron_variant, non_coding_transcript_variant		5

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152150

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

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:

0.0000477

AC:

AN:

251322

Hom.:

AF XY:

0.0000442

AC XY:

AN XY:

135824

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.000318

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000880

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000164

AC:

AN:

1461608

Hom.:

Cov.:

AF XY:

0.0000165

AC XY:

AN XY:

727118

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.000358

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:

0.0000331

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152150

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74318

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

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:

0.0000282

Hom.:

Bravo

AF:

0.0000113

ExAC

AF:

0.00000824

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:6

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not provided

Uncertain:3

Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Sep 01, 2022	This sequence change replaces serine, which is neutral and polar, with phenylalanine, which is neutral and non-polar, at codon 251 of the TTPA protein (p.Ser251Phe). This variant is present in population databases (rs756313678, gnomAD 0.03%). 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: 448840). 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: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). 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. -
Uncertain significance, criteria provided, single submitter	clinical testing	Athena Diagnostics	Oct 25, 2022	Available data are insufficient to determine the clinical significance of the variant at this time. The frequency of this variant in the general population is uninformative in assessment of its pathogenicity (http://gnomad.broadinstitute.org). Computational tools predict that this variant is not damaging. -
Uncertain significance, criteria provided, single submitter	clinical testing	Mayo Clinic Laboratories, Mayo Clinic	Apr 19, 2022	- -

Familial isolated deficiency of vitamin E

Uncertain:2

Uncertain significance, no assertion criteria provided	clinical testing	Natera, Inc.	Nov 11, 2019	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Jan 13, 2018	This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Inborn genetic diseases

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jun 11, 2024

The c.752C>T (p.S251F) alteration is located in exon 5 (coding exon 5) of the TTPA gene. This alteration results from a C to T substitution at nucleotide position 752, causing the serine (S) at amino acid position 251 to be replaced by a phenylalanine (F). 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

Uncertain

0.45

BayesDel_addAF

Benign

-0.15

BayesDel_noAF

Benign

-0.14

CADD

Uncertain

DANN

Uncertain

0.99

DEOGEN2

Uncertain

0.78

Eigen

Uncertain

0.30

Eigen_PC

Uncertain

0.35

FATHMM_MKL

Uncertain

0.90

LIST_S2

Benign

0.78

M_CAP

Uncertain

0.088

MetaRNN

Uncertain

0.53

MetaSVM

Uncertain

0.023

MutationAssessor

Uncertain

2.7

MutationTaster

Benign

0.94

PrimateAI

Benign

0.48

PROVEAN

Uncertain

-2.7

REVEL

Uncertain

0.41

Sift

Uncertain

0.012

Sift4G

Benign

0.13

Polyphen

0.86

Vest4

0.37

MutPred

0.51

Loss of disorder (P = 0.0393);

MVP

0.91

MPC

0.45

ClinPred

0.39

GERP RS

4.0

Varity_R

0.55

gMVP

0.71

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