14-88824683-G-A

Variant names:

Variant summary

Our verdict is Benign. The variant received -13 ACMG points: 0P and 13B. BP4_StrongBP6BS1BS2

The ENST00000555057.5(TTC8):n.-25G>A variant causes a non coding transcript exon change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00148 in 1,571,366 control chromosomes in the GnomAD database, including 9 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 0.0037 ( 3 hom., cov: 32)

Exomes 𝑓: 0.0012 ( 6 hom. )

Consequence

TTC8
ENST00000555057.5 non_coding_transcript_exon

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1B:2

Conservation

PhyloP100: -1.29

Publications

2 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: Benign. The variant received -13 ACMG points.

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.79).

BP6

Variant 14-88824683-G-A is Benign according to our data. Variant chr14-88824683-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 262512.

BS1

Variant frequency is greater than expected in population afr. GnomAd4 allele frequency = 0.00367 (559/152214) while in subpopulation AFR AF = 0.00879 (365/41540). AF 95% confidence interval is 0.00804. There are 3 homozygotes in GnomAd4. There are 267 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check.

BS2

High Homozygotes in GnomAd4 at 3 AD,AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TTC8	NM_144596.4 link	c.-25G>A		5_prime_UTR_variant	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.-25G>A		5_prime_UTR_variant	Exon 1 of 15	2	NM_144596.4	ENSP00000370031.2		Q8TAM2-4

Frequencies

GnomAD3 genomes

AF:

0.00367

AC:

558

AN:

152096

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00879

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00687

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000621

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.0190

Gnomad NFE

AF:

0.000779

Gnomad OTH

AF:

0.0129

GnomAD2 exomes

AF:

0.00184

AC:

352

AN:

191616

AF XY:

0.00152

show subpopulations

Gnomad AFR exome

AF:

0.00805

Gnomad AMR exome

AF:

0.00473

Gnomad ASJ exome

AF:

0.000226

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00119

Gnomad OTH exome

AF:

0.00578

GnomAD4 exome

AF:

0.00125

AC:

1771

AN:

1419152

Hom.:

Cov.:

AF XY:

0.00114

AC XY:

800

AN XY:

703702

show subpopulations

African (AFR)

AF:

0.00898

AC:

293

AN:

32628

American (AMR)

AF:

0.00498

AC:

199

AN:

39948

Ashkenazi Jewish (ASJ)

AF:

0.000314

AC:

AN:

25446

East Asian (EAS)

AF:

0.00

AC:

AN:

38088

South Asian (SAS)

AF:

0.000232

AC:

AN:

82038

European-Finnish (FIN)

AF:

0.0000598

AC:

AN:

50172

Middle Eastern (MID)

AF:

0.00821

AC:

AN:

4748

European-Non Finnish (NFE)

AF:

0.000933

AC:

1014

AN:

1087368

Other (OTH)

AF:

0.00334

AC:

196

AN:

58716

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.505

Heterozygous variant carriers

190

285

380

475

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Exome Hom

Variant carriers

138

184

230

<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:

0.00367

AC:

559

AN:

152214

Hom.:

Cov.:

AF XY:

0.00359

AC XY:

267

AN XY:

74416

show subpopulations

African (AFR)

AF:

0.00879

AC:

365

AN:

41540

American (AMR)

AF:

0.00686

AC:

105

AN:

15296

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3466

East Asian (EAS)

AF:

0.00

AC:

AN:

5146

South Asian (SAS)

AF:

0.000621

AC:

AN:

4828

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10612

Middle Eastern (MID)

AF:

0.0204

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.000779

AC:

AN:

68004

Other (OTH)

AF:

0.0128

AC:

AN:

2116

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.489

Heterozygous variant carriers

107

134

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Genome Hom

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:

0.000643

Hom.:

Bravo

AF:

0.00492

Asia WGS

AF:

0.00173

AC:

AN:

3478

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1Benign:2

Revision: criteria provided, conflicting classifications

LINK: link

Submissions by phenotype

Retinitis pigmentosa

Uncertain:1

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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. -

Bardet-Biedl syndrome 8

Benign:1

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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 and internal cut-off values, a variant classified as likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

TTC8-related disorder

Benign:1

Aug 16, 2021

PreventionGenetics, part of Exact Sciences

Significance:Benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

This variant is classified as benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications). -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.79

CADD

Benign

2.9

(source)

DANN

Benign

0.91

PhyloP100

-1.3

PromoterAI

-0.49

Neutral

(source)

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.0

Mutation Taster

=300/0

polymorphism

(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