14-88824709-T-G

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 1P and 0B. PVS1_Supporting

The NM_144596.4(TTC8):c.2T>G(p.Met1?) variant causes a start lost change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000685 in 1,606,386 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 (no stars).

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000062 ( 0 hom. )

Consequence

TTC8
NM_144596.4 start_lost

Scores

Clinical Significance

Uncertain significance no assertion criteria provided U:1

Conservation

PhyloP100: 2.97

Publications

0 publications found

Variant links:

Genes affected

TTC8 (HGNC:20087): (tetratricopeptide repeat domain 8) This gene encodes a protein that has been directly linked to Bardet-Biedl syndrome. The primary features of this syndrome include retinal dystrophy, obesity, polydactyly, renal abnormalities and learning disabilities. Experimentation in non-human eukaryotes suggests that this gene is expressed in ciliated cells and that it is involved in the formation of cilia. A mutation in this gene has also been implicated in nonsyndromic retinitis pigmentosa. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jan 2014]

TTC8 Gene-Disease associations (from GenCC):

Bardet-Biedl syndrome 8
Inheritance: AR Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Genomics England PanelApp, Ambry Genetics, Labcorp Genetics (formerly Invitae), G2P
retinitis pigmentosa 51
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P
retinitis pigmentosa
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
Bardet-Biedl syndrome
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

TTC8 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 1 ACMG points.

PVS1

Start lost variant, no pathogenic variants between lost start and next in-frame start position. Next in-frame start position is after 5 codons. Genomic position: 88824720. Lost 0.008 part of the original CDS.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTC8	NM_144596.4 link	c.2T>G	p.Met1?	start_lost	Exon 1 of 15	ENST00000380656.7	NP_653197.2	Q8TAM2-4Q86U25

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TTC8	ENST00000380656.7 link	c.2T>G	p.Met1?	start_lost	Exon 1 of 15	2	NM_144596.4	ENSP00000370031.2		Q8TAM2-4

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152108

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:

0.0000294

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000429

AC:

AN:

232976

AF XY:

0.00

show subpopulations

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 FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000961

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000619

AC:

AN:

1454278

Hom.:

Cov.:

AF XY:

0.00000692

AC XY:

AN XY:

722790

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33348

American (AMR)

AF:

0.00

AC:

AN:

43932

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25928

East Asian (EAS)

AF:

0.00

AC:

AN:

39502

South Asian (SAS)

AF:

0.00

AC:

AN:

84954

European-Finnish (FIN)

AF:

0.00

AC:

AN:

52246

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5362

European-Non Finnish (NFE)

AF:

0.00000812

AC:

AN:

1108938

Other (OTH)

AF:

0.00

AC:

AN:

60068

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.458

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152108

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

74316

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41432

American (AMR)

AF:

0.00

AC:

AN:

15284

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3460

East Asian (EAS)

AF:

0.00

AC:

AN:

5162

South Asian (SAS)

AF:

0.00

AC:

AN:

4834

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10610

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000294

AC:

AN:

68006

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.500

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: no assertion criteria provided

LINK: link

Submissions by phenotype

TTC8-related disorder

Uncertain:1

Sep 26, 2024

PreventionGenetics, part of Exact Sciences

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

The TTC8 c.2T>G variant is predicted to disrupt the translation initiation site (Start Loss). To our knowledge, this variant, or other start-loss variants, have not been reported in the literature in patients with TTC8-related disorders. This variant is reported in 0.0017% of alleles in individuals of European (Non-Finnish) descent in gnomAD. Of note, an additional methionine residue resides four amino acids downstream. At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.63

BayesDel_noAF

Uncertain

0.10

CADD

Benign

(source)

DANN

Uncertain

0.98

DEOGEN2

Benign

0.079

T;T;.;.;T;T;.;.;.

Eigen

Benign

-0.054

Eigen_PC

Benign

0.027

FATHMM_MKL

Benign

0.68

LIST_S2

Uncertain

0.90

D;D;D;D;.;.;D;.;D

M_CAP

Pathogenic

0.54

MetaRNN

Pathogenic

0.98

D;D;D;D;D;D;D;D;D

MetaSVM

Benign

-0.37

PhyloP100

3.0

PROVEAN

Uncertain

-4.2

D;.;N;.;N;N;N;N;N

REVEL

Uncertain

0.48

Sift

Pathogenic

0.0

D;.;D;.;D;D;D;D;D

Sift4G

Uncertain

0.022

D;D;D;D;D;D;T;D;D

Polyphen

0.74, 0.23, 0.036

.;.;P;.;.;.;B;P;B

Vest4

0.82

MutPred

1.0

Gain of solvent accessibility (P = 0.11);Gain of solvent accessibility (P = 0.11);Gain of solvent accessibility (P = 0.11);Gain of solvent accessibility (P = 0.11);Gain of solvent accessibility (P = 0.11);Gain of solvent accessibility (P = 0.11);Gain of solvent accessibility (P = 0.11);Gain of solvent accessibility (P = 0.11);Gain of solvent accessibility (P = 0.11);

MVP

0.90

ClinPred

1.0

GERP RS

4.4

PromoterAI

-0.68

Under-expression

(source)

gMVP

0.59

Mutation Taster

=60/140

disease causing

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over