chr17-78131625-C-CCTG

Variant names:

• chr17-78131625-C-CCTG
• NM_152468.5:c.38_40dupCTG

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PM2 PM4_Supporting

The NM_152468.5(TMC8):​c.38_40dupCTG​(p.Pro13_Gly14insAla) variant causes a disruptive inframe insertion change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. G14G) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 34)
• Consequence: TMC8 NM_152468.5 disruptive_inframe_insertion
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.312
• Publications: 0 publications found

Genes affected

TMC8 (HGNC:20474): (transmembrane channel like 8) Epidermodysplasia verruciformis (EV) is an autosomal recessive dermatosis characterized by abnormal susceptibility to human papillomaviruses (HPVs) and a high rate of progression to squamous cell carcinoma on sun-exposed skin. EV is caused by mutations in either of two adjacent genes located on chromosome 17q25.3. Both of these genes encode integral membrane proteins that localize to the endoplasmic reticulum and are predicted to form transmembrane channels. This gene encodes a transmembrane channel-like protein with 8 predicted transmembrane domains and 3 leucine zipper motifs. [provided by RefSeq, Jul 2008]

TMC6 (HGNC:18021): (transmembrane channel like 6) Epidermodysplasia verruciformis (EV) is an autosomal recessive dermatosis characterized by abnormal susceptibility to human papillomaviruses (HPVs) and a high rate of progression to squamous cell carcinoma on sun-exposed skin. EV is caused by mutations in either of two adjacent genes located on chromosome 17q25.3. Both of these genes encode integral membrane proteins that localize to the endoplasmic reticulum and are predicted to form transmembrane channels. This gene encodes a transmembrane channel-like protein with 10 transmembrane domains and 2 leucine zipper motifs. [provided by RefSeq, Jul 2008]

TMC6 Gene-Disease associations (from GenCC):

• epidermodysplasia verruciformis, susceptibility to, 1

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, Ambry Genetics
• epidermodysplasia verruciformis

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM4: Nonframeshift variant in NON repetitive region in NM_152468.5. Strenght limited to Supporting due to length of the change: 1aa.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
TMC8	NM_152468.5	c.38_40dupCTG	p.Pro13_Gly14insAla	disruptive_inframe_insertion	Exon 2 of 16	ENST00000318430.10	NP_689681.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
TMC8	ENST00000318430.10	c.38_40dupCTG	p.Pro13_Gly14insAla	disruptive_inframe_insertion	Exon 2 of 16	1	NM_152468.5	ENSP00000325561.4

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 34

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Epidermodysplasia verruciformis Uncertain:1

Jun 30, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant, c.38_40dup, results in the insertion of 1 amino acid(s) of the TMC8 protein (p.Pro13_Gly14insAla), but otherwise preserves the integrity of the reading frame. This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with TMC8-related conditions. Experimental studies and prediction algorithms are not available or were not evaluated, and the functional significance of this variant is currently unknown. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
PhyloP100		0.31

Splicing

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

hg19: chr17-76127706;