14-88877326-G-T

Variant names:

• chr14-88877326-G-T
• rs142073418
• NM_144596.4:c.1464G>T

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PM2 BP4_Strong BP7

The NM_144596.4(TTC8):​c.1464G>T​(p.Ala488Ala) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,461,440 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. A488A) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: TTC8 NM_144596.4 synonymous
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -0.0970
• Publications: 0 publications found

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

ACMG classification

Our verdict: Likely_benign. The variant received -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (REVEL=0.003).
• BP7: Synonymous conserved (PhyloP=-0.097 with no splicing effect.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_144596.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTC8	NM_144596.4	MANE Select	c.1464G>T	p.Ala488Ala	synonymous	Exon 15 of 15	NP_653197.2
	TTC8	NM_001288781.1		c.1512G>T	p.Ala504Ala	synonymous	Exon 16 of 16	NP_001275710.1
	TTC8	NM_198309.3		c.1434G>T	p.Ala478Ala	synonymous	Exon 15 of 15	NP_938051.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTC8	ENST00000380656.7	TSL:2 MANE Select	c.1464G>T	p.Ala488Ala	synonymous	Exon 15 of 15	ENSP00000370031.2
	TTC8	ENST00000338104.10	TSL:1	c.1512G>T	p.Ala504Ala	synonymous	Exon 15 of 15	ENSP00000337653.6
	TTC8	ENST00000622513.4	TSL:1	c.1434G>T	p.Ala478Ala	synonymous	Exon 14 of 14	ENSP00000482721.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461440 Hom.: 0 Cov.: 31 AF XY: 0.00000275 AC XY: 2 AN XY: 727012

African (AFR) AF: 0.00 AC: 0 AN: 33462

American (AMR) AF: 0.00 AC: 0 AN: 44704

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39614

South Asian (SAS) AF: 0.00 AC: 0 AN: 86246

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53396

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 0.00000450 AC: 5 AN: 1111748

Other (OTH) AF: 0.00 AC: 0 AN: 60374

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.49
CADD	Benign	4.5
DANN	Benign	0.57
PhyloP100		-0.097

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

Other links and lift over

dbSNP: rs142073418; hg19: chr14-89343670;