12-123688199-T-A

Variant names:

• chr12-123688199-T-A
• rs7302449
• NM_024809.5:c.891+22T>A

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2 BP4_Strong

The NM_024809.5(TCTN2):​c.891+22T>A variant causes a intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000138 in 1,452,974 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.

• Frequency:
  • Genomes: not found (cov: 30)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: TCTN2 NM_024809.5 intron
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: -0.561
• Publications: 11 publications found

Genes affected

TCTN2 (HGNC:25774): (tectonic family member 2) This gene encodes a type I membrane protein that belongs to the tectonic family. Studies in mice suggest that this protein may be involved in hedgehog signaling, and essential for ciliogenesis. Mutations in this gene are associated with Meckel syndrome type 8. Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Oct 2011]

TCTN2 Gene-Disease associations (from GenCC):

• Joubert syndrome 24

  Inheritance: AR Classification: DEFINITIVE, STRONG, MODERATE Submitted by: ClinGen, Ambry Genetics, Labcorp Genetics (formerly Invitae), PanelApp Australia, G2P
• Meckel syndrome, type 8

  Inheritance: AR Classification: STRONG Submitted by: PanelApp Australia
• Joubert syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• Meckel syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_benign. The variant received -2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.81).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_024809.5. 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
	TCTN2	NM_024809.5	MANE Select	c.891+22T>A		intron	N/A	NP_079085.2
	TCTN2	NM_001143850.3		c.888+22T>A		intron	N/A	NP_001137322.1	Q96GX1-2
	TCTN2	NM_001410989.1		c.891+22T>A		intron	N/A	NP_001397918.1	A0A7P0T8X4

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	TCTN2	ENST00000303372.7	TSL:1 MANE Select	c.891+22T>A		intron	N/A	ENSP00000304941.5	Q96GX1-1
	TCTN2	ENST00000426174.6	TSL:2	c.888+22T>A		intron	N/A	ENSP00000395171.2	Q96GX1-2
	TCTN2	ENST00000965363.1		c.891+22T>A		intron	N/A	ENSP00000635422.1

Frequencies

GnomAD3 genomes Cov.: 30

GnomAD4 exome AF: 0.00000138 AC: 2 AN: 1452974 Hom.: 0 Cov.: 34 AF XY: 0.00 AC XY: 0 AN XY: 723062

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 32960

American (AMR) AF: 0.00 AC: 0 AN: 44378

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25960

East Asian (EAS) AF: 0.00 AC: 0 AN: 39576

South Asian (SAS) AF: 0.00 AC: 0 AN: 85568

European-Finnish (FIN) AF: 0.0000191 AC: 1 AN: 52470

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5726

European-Non Finnish (NFE) AF: 9.04e-7 AC: 1 AN: 1106342

Other (OTH) AF: 0.00 AC: 0 AN: 59994

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.0000000000983081), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 30

Alfa AF: 0.00 Hom.: 1993

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.81
CADD	Benign	0.13
DANN	Benign	0.64
PhyloP100		-0.56

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

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

Other links and lift over

dbSNP: rs7302449;

hg19: chr12-124172746;