rs775836730

Variant names:

• chr2-165929200-CA-C
• rs775836730
• NM_024753.5:c.1320delT

Variant summary

Our verdict is Pathogenic. The variant received 16 ACMG points: 16P and 0B. PVS1 PP5_Very_Strong

The NM_024753.5(TTC21B):​c.1320delT​(p.Phe440LeufsTer4) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000663 in 1,612,878 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: 𝑓 0.000026 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000071 (0 hom.)
• Consequence: TTC21B NM_024753.5 frameshift
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 3.10
• Publications: 2 publications found

Genes affected

TTC21B (HGNC:25660): (tetratricopeptide repeat domain 21B) This gene encodes a member of TTC21 family, containing several tetratricopeptide repeat (TPR) domains. This protein is localized to the cilium axoneme, and may play a role in retrograde intraflagellar transport in cilia. Mutations in this gene are associated with various ciliopathies, nephronophthisis 12, and asphyxiating thoracic dystrophy 4. [provided by RefSeq, Oct 2011]

TTC21B Gene-Disease associations (from GenCC):

• asphyxiating thoracic dystrophy 4

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics
• nephronophthisis 12

  Inheritance: AR, AD Classification: DEFINITIVE, STRONG, LIMITED Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, Ambry Genetics
• Jeune syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• nephronophthisis 2

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 16 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PP5: Variant 2-165929200-CA-C is Pathogenic according to our data. Variant chr2-165929200-CA-C is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 446650.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_024753.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTC21B	NM_024753.5	MANE Select	c.1320delT	p.Phe440LeufsTer4	frameshift	Exon 11 of 29	NP_079029.3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TTC21B	ENST00000243344.8	TSL:1 MANE Select	c.1320delT	p.Phe440LeufsTer4	frameshift	Exon 11 of 29	ENSP00000243344.7	Q7Z4L5-1
	TTC21B	ENST00000464374.5	TSL:1	n.1360delT		non_coding_transcript_exon	Exon 11 of 11
	TTC21B	ENST00000679840.1		c.1320delT	p.Phe440LeufsTer4	frameshift	Exon 11 of 27	ENSP00000505248.1	A0A7P0T8P4

Frequencies

GnomAD3 genomes AF: 0.0000263 AC: 4 AN: 152050 Hom.: 0 Cov.: 32

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: 0.0000589

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000399 AC: 10 AN: 250524 AF XY: 0.0000369

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: 0.0000884

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000705 AC: 103 AN: 1460828 Hom.: 0 Cov.: 31 AF XY: 0.0000633 AC XY: 46 AN XY: 726712

African (AFR) AF: 0.00 AC: 0 AN: 33440

American (AMR) AF: 0.00 AC: 0 AN: 44622

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26100

East Asian (EAS) AF: 0.00 AC: 0 AN: 39564

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86198

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53390

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5756

European-Non Finnish (NFE) AF: 0.0000828 AC: 92 AN: 1111424

Other (OTH) AF: 0.000166 AC: 10 AN: 60334

GnomAD4 genome AF: 0.0000263 AC: 4 AN: 152050 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74264

African (AFR) AF: 0.00 AC: 0 AN: 41432

American (AMR) AF: 0.00 AC: 0 AN: 15254

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5188

South Asian (SAS) AF: 0.00 AC: 0 AN: 4834

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10620

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000589 AC: 4 AN: 67936

Other (OTH) AF: 0.00 AC: 0 AN: 2088

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000529

EpiCase AF: 0.0000546

EpiControl AF: 0.0000593

ClinVar

ClinVar submissions

Significance: Pathogenic/Likely pathogenic

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
2	-	-	Type IV short rib polydactyly syndrome (2)
1	-	-	Asphyxiating thoracic dystrophy 4 (1)
1	-	-	Asphyxiating thoracic dystrophy 4;C3151186:Nephronophthisis 12 (1)
1	-	-	Jeune thoracic dystrophy;C0687120:Nephronophthisis (1)
1	-	-	Retinal dystrophy (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		3.1
Mutation Taster		=0/200	disease causing (ClinVar)

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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

dbSNP: rs775836730; hg19: chr2-166785710;