12-110628854-T-C

Position:

• chr12-110628854-T-C

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_001082538.3(TCTN1):​c.560T>C​(p.Leu187Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,402 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 15/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. L187L) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: TCTN1 NM_001082538.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -0.0590

Genes affected

TCTN1 (HGNC:26113): (tectonic family member 1) This gene encodes a member of a family of secreted and transmembrane proteins. The orthologous gene in mouse functions downstream of smoothened and rab23 to modulate hedgehog signal transduction. This protein is a component of the tectonic-like complex, which forms a barrier between the ciliary axoneme and the basal body. A mutation in this gene was found in a family with Joubert syndrome-13. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Feb 2016]

HVCN1 (HGNC:28240): (hydrogen voltage gated channel 1) This gene encodes a voltage-gated protein channel protein expressed more highly in certain cells of the immune system. Phagocytic cells produce superoxide anions which require this channel protein, and in B cells this same process facilitates antibody production. This same channel protein, however, can also regulate functions in other cells including spermatozoa. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jan 2012]

ACMG classification

Verdict is Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.06863955).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TCTN1	NM_001082538.3	c.560T>C	p.Leu187Ser	missense_variant	4/15	ENST00000397659.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TCTN1	ENST00000397659.9	c.560T>C	p.Leu187Ser	missense_variant	4/15	1	NM_001082538.3	A1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461402 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727046

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Meckel-Gruber syndrome;C0431399:Familial aplasia of the vermis Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Apr 06, 2021

In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Deleterious"; PolyPhen-2: "Benign"; Align-GVGD: "Class C55". The serine amino acid residue is found in multiple mammalian species, suggesting that this missense change does not adversely affect protein function. These predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with TCTN1-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces leucine with serine at codon 187 of the TCTN1 protein (p.Leu187Ser). The leucine residue is moderately conserved and there is a large physicochemical difference between leucine and serine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.070
BayesDel_addAF	Benign	-0.016	T
BayesDel_noAF	Benign	-0.26
CADD	Benign	8.0
DANN	Benign	0.97
DEOGEN2	Benign	0.22	.;.;T;.;.;.
Eigen	Benign	-1.0
Eigen_PC	Benign	-1.1
FATHMM_MKL	Benign	0.032	N
LIST_S2	Benign	0.52	T;T;T;T;T;T
M_CAP	Benign	0.020	T
MetaRNN	Benign	0.069	T;T;T;T;T;T
MetaSVM	Benign	-0.74	T
MutationAssessor	Benign	0.94	.;.;L;L;L;.
MutationTaster	Benign	1.0	N;N;N;N;N
PrimateAI	Benign	0.26	T
PROVEAN	Benign	-0.050	.;.;N;N;N;.
REVEL	Uncertain	0.30
Sift	Benign	0.71	.;.;T;T;T;.
Sift4G	Benign	0.12	T;T;T;T;T;T
Polyphen		0.076	B;.;B;B;B;.
Vest4		0.073
MutPred		0.64		Gain of catalytic residue at N188 (P = 4e-04);Gain of catalytic residue at N188 (P = 4e-04);Gain of catalytic residue at N188 (P = 4e-04);Gain of catalytic residue at N188 (P = 4e-04);Gain of catalytic residue at N188 (P = 4e-04);.;
MVP		0.37
MPC		0.28
ClinPred		0.086	T
GERP RS		-6.3
Varity_R		0.025
gMVP		0.71

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: rs2066031755; hg19: chr12-111066659;