NM_024753.5:c.1963C>T

Variant names:

• chr2-165915376-G-A
• rs138937289
• NM_024753.5:c.1963C>T
• TTC21B p.Arg655Trp

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PP3_Strong

The NM_024753.5(TTC21B):​c.1963C>T​(p.Arg655Trp) variant causes a missense change. The variant allele was found at a frequency of 0.0000452 in 1,613,920 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R655Q) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000033 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000047 (0 hom.)
• Consequence: TTC21B NM_024753.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 6.48
• Publications: 4 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: Uncertain_significance. The variant received 4 ACMG points.

• PP3: MetaRNN computational evidence supports a deleterious effect, 0.961

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.1963C>T	p.Arg655Trp	missense	Exon 15 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.1963C>T	p.Arg655Trp	missense	Exon 15 of 29	ENSP00000243344.7	Q7Z4L5-1
	TTC21B	ENST00000679840.1		c.1963C>T	p.Arg655Trp	missense	Exon 15 of 27	ENSP00000505248.1	A0A7P0T8P4
	TTC21B	ENST00000679799.1		c.1963C>T	p.Arg655Trp	missense	Exon 15 of 28	ENSP00000505208.1	A0A494C0N4

Frequencies

GnomAD3 genomes AF: 0.0000329 AC: 5 AN: 152100 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: 0.0000735

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000438 AC: 11 AN: 251282 AF XY: 0.0000442

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000867

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000704

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000465 AC: 68 AN: 1461820 Hom.: 0 Cov.: 32 AF XY: 0.0000550 AC XY: 40 AN XY: 727212

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.0000671 AC: 3 AN: 44724

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 39686

South Asian (SAS) AF: 0.0000232 AC: 2 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53416

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

European-Non Finnish (NFE) AF: 0.0000567 AC: 63 AN: 1111968

Other (OTH) AF: 0.00 AC: 0 AN: 60394

GnomAD4 genome AF: 0.0000329 AC: 5 AN: 152100 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74290

African (AFR) AF: 0.00 AC: 0 AN: 41414

American (AMR) AF: 0.00 AC: 0 AN: 15266

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3464

East Asian (EAS) AF: 0.00 AC: 0 AN: 5194

South Asian (SAS) AF: 0.00 AC: 0 AN: 4814

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10610

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

European-Non Finnish (NFE) AF: 0.0000735 AC: 5 AN: 68022

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

Alfa AF: 0.000126 Hom.: 0

Bravo AF: 0.0000604

EpiCase AF: 0.000164

EpiControl AF: 0.0000593

ClinVar

ClinVar submissions

Significance: Uncertain significance

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
-	1	-	Asphyxiating thoracic dystrophy 4;C3151186:Nephronophthisis 12 (1)
-	1	-	Jeune thoracic dystrophy;C0687120:Nephronophthisis (1)
-	1	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.23
BayesDel_addAF	Pathogenic	0.28	D
BayesDel_noAF	Pathogenic	0.35
CADD	Pathogenic	30
DANN	Pathogenic	1.0
DEOGEN2	Uncertain	0.56	D
Eigen	Pathogenic	0.73
Eigen_PC	Uncertain	0.64
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Uncertain	0.21	D
MetaRNN	Pathogenic	0.96	D
MetaSVM	Uncertain	0.53	D
MutationAssessor	Pathogenic	3.2	M
PhyloP100		6.5
PrimateAI	Uncertain	0.74	T
PROVEAN	Pathogenic	-7.4	D
REVEL	Pathogenic	0.83
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1
Varity_R		0.75
gMVP		0.67
Mutation Taster		=80/20	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs138937289;

hg19: chr2-166771886;

COSMIC: COSV54627564;