rs774283073

chr8-63064311-T-C

Variant summary

Our verdict is Benign. Variant got -10 ACMG points: 0P and 10B. BP4_Strong BP6 BP7 BS1

The NM_000370.3(TTPA):c.558A>G(p.Ser186=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000779 in 1,604,274 control chromosomes in the GnomAD database, including 2 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency:
  • Genomes: 𝑓 0.000033 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000083 (2 hom.)
• Consequence: TTPA NM_000370.3 synonymous
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:2
• Conservation: PhyloP100: 0.686

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]

ACMG classification

Verdict is Benign. Variant got -10 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.54).
• BP6: Variant 8-63064311-T-C is Benign according to our data. Variant chr8-63064311-T-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 586911.We mark this variant Likely_benign, oryginal submissions are: {Uncertain_significance=1, Benign=1, Likely_benign=1}.
• BP7: Synonymous conserved (PhyloP=0.686 with no splicing effect.
• BS1: Variant frequency is greater than expected in population sas. gnomad4_exome allele frequency = 0.0000826 (120/1452138) while in subpopulation SAS AF= 0.00116 (99/85712). AF 95% confidence interval is 0.00097. There are 2 homozygotes in gnomad4_exome. There are 80 alleles in male gnomad4_exome subpopulation. Median coverage is 28. This position pass quality control queck.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTPA	NM_000370.3	c.558A>G	p.Ser186=	synonymous_variant	4/5	ENST00000260116.5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTPA	ENST00000260116.5	c.558A>G	p.Ser186=	synonymous_variant	4/5	1	NM_000370.3	P1
TTPA	ENST00000521138.1	n.233-15708A>G		intron_variant, non_coding_transcript_variant		5

Frequencies

GnomAD3 genomes AF: 0.0000329 AC: 5 AN: 152136 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000621

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000207 AC: 51 AN: 246398 Hom.: 1 AF XY: 0.000255 AC XY: 34 AN XY: 133444

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00166

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000166

GnomAD4 exome AF: 0.0000826 AC: 120 AN: 1452138 Hom.: 2 Cov.: 28 AF XY: 0.000111 AC XY: 80 AN XY: 722846

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000225

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000253

Gnomad4 SAS exome AF: 0.00116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000272

Gnomad4 OTH exome AF: 0.000233

GnomAD4 genome AF: 0.0000329 AC: 5 AN: 152136 Hom.: 0 Cov.: 33 AF XY: 0.0000404 AC XY: 3 AN XY: 74308

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.0000655

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000621

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Bravo AF: 0.0000113

Asia WGS AF: 0.000289 AC: 1 AN: 3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Benign:2

Likely benign, criteria provided, single submitter	clinical testing	Athena Diagnostics	Nov 13, 2017	- -
Benign, criteria provided, single submitter	clinical testing	Invitae	Jan 12, 2024	- -

Familial isolated deficiency of vitamin E Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.54
Cadd	Benign	8.7
Dann	Benign	0.75

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs774283073; hg19: chr8-63976870;