2-165874099-C-T

Variant summary

Our verdict is Benign. Variant got -14 ACMG points: 0P and 14B. BP4_Strong BP6_Moderate BS1 BS2

The NM_024753.5(TTC21B):c.*656G>A variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0041 in 152,224 control chromosomes in the GnomAD database, including 11 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★).

• Frequency:
  • Genomes: 𝑓 0.0041 (11 hom., cov: 32)
  • Exomes 𝑓: 0.011 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: TTC21B NM_024753.5 3_prime_UTR
• Clinical Significance: Likely benign criteria provided, single submitter B:2
• Conservation: PhyloP100: -0.969

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]

ACMG classification

Verdict is Benign. Variant got -14 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.98).
• BP6: Variant 2-165874099-C-T is Benign according to our data. Variant chr2-165874099-C-T is described in ClinVar as [Likely_benign]. Clinvar id is 331805.Status of the report is criteria_provided_single_submitter, 1 stars.
• BS1: Variant frequency is greater than expected in population eas. gnomad4 allele frequency = 0.0041 (624/152224) while in subpopulation EAS AF= 0.033 (171/5182). AF 95% confidence interval is 0.029. There are 11 homozygotes in gnomad4. There are 406 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.
• BS2: High Homozygotes in GnomAd at 11 AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TTC21B	NM_024753.5	c.*656G>A		3_prime_UTR_variant	29/29	ENST00000243344.8
TTC21B	XM_011511871.4	c.*656G>A		3_prime_UTR_variant	24/24
TTC21B	XM_047445870.1	c.*656G>A		3_prime_UTR_variant	25/25

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TTC21B	ENST00000243344.8	c.*656G>A		3_prime_UTR_variant	29/29	1	NM_024753.5	P1

Frequencies

GnomAD3 genomes AF: 0.00412 AC: 626 AN: 152106 Hom.: 11 Cov.: 32

Gnomad AFR AF: 0.000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00602

Gnomad ASJ AF: 0.00519

Gnomad EAS AF: 0.0333

Gnomad SAS AF: 0.00269

Gnomad FIN AF: 0.0250

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000706

Gnomad OTH AF: 0.00334

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 0.0106 AC: 1 AN: 94 Hom.: 0 Cov.: 0 AF XY: 0.00 AC XY: 0 AN XY: 64

Gnomad4 AMR exome AF: 0.250

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

GnomAD4 genome AF: 0.00410 AC: 624 AN: 152224 Hom.: 11 Cov.: 32 AF XY: 0.00546 AC XY: 406 AN XY: 74422

Gnomad4 AFR AF: 0.000241

Gnomad4 AMR AF: 0.00602

Gnomad4 ASJ AF: 0.00519

Gnomad4 EAS AF: 0.0330

Gnomad4 SAS AF: 0.00269

Gnomad4 FIN AF: 0.0250

Gnomad4 NFE AF: 0.000706

Gnomad4 OTH AF: 0.00331

Alfa AF: 0.00286 Hom.: 0

Bravo AF: 0.00249

Asia WGS AF: 0.0190 AC: 66 AN: 3478

ClinVar

Significance: Likely benign

Submissions summary: Benign:2

Revision: criteria provided, single submitter

Submissions by phenotype

Asphyxiating thoracic dystrophy 4 Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

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. -

Nephronophthisis 12 Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.98
Cadd	Benign	0.76
Dann	Benign	0.51

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

LitVar

Other links and lift over

dbSNP: rs180737925; hg19: chr2-166730609;