12-82857123-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_152588.3(TMTC2):c.197G>A(p.Arg66Gln) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,834 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. R66W) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: TMTC2 NM_152588.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 10.0

Genes affected

TMTC2 (HGNC:25440): (transmembrane O-mannosyltransferase targeting cadherins 2) The protein encoded by this gene is an integral membrane protein localized to the endoplasmic reticulum (ER). The encoded protein contains many tetratricopeptide repeats, sequences known for being involved in protein-protein interactions. This protein binds both the calcium uptake pump SERCA2B and the carbohydrate-binding chaperone calnexin, and it appears to play a role in calcium homeostasis in the ER. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Feb 2016]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.925

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
TMTC2	NM_152588.3	c.197G>A	p.Arg66Gln	missense_variant	2/12	ENST00000321196.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
TMTC2	ENST00000321196.8	c.197G>A	p.Arg66Gln	missense_variant	2/12	1	NM_152588.3	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.0000119 AC: 3 AN: 251360 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135852

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 SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461834 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 727214

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000671

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.0000116

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

May 23, 2023

The c.197G>A (p.R66Q) alteration is located in exon 2 (coding exon 2) of the TMTC2 gene. This alteration results from a G to A substitution at nucleotide position 197, causing the arginine (R) at amino acid position 66 to be replaced by a glutamine (Q). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.28	D
BayesDel_noAF	Pathogenic	0.36
Cadd	Pathogenic	33
Dann	Pathogenic	1.0
DEOGEN2	Benign	0.22	T;.;T
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.95	D;D;D
M_CAP	Uncertain	0.23	D
MetaRNN	Pathogenic	0.93	D;D;D
MetaSVM	Uncertain	0.64	D
MutationAssessor	Pathogenic	4.3	H;.;.
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Pathogenic	0.83	D
PROVEAN	Uncertain	-3.7	D;D;D
REVEL	Pathogenic	0.66
Sift	Pathogenic	0.0	D;D;D
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		1.0	D;D;.
Vest4		0.97
MutPred		0.79		Loss of methylation at R66 (P = 0.028);Loss of methylation at R66 (P = 0.028);.;
MVP		0.85
MPC		0.70
ClinPred		1.0	D
GERP RS		6.2
Varity_R		0.75
gMVP		0.97

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: rs747714516; hg19: chr12-83250902;