6-42960952-T-C

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_018960.6(GNMT):c.185T>C(p.Leu62Pro) variant causes a missense change. The variant allele was found at a frequency of 0.000000709 in 1,410,276 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 (★).

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 7.1e-7 (0 hom.)
• Consequence: GNMT NM_018960.6 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.67

Genes affected

GNMT (HGNC:4415): (glycine N-methyltransferase) The protein encoded by this gene is an enzyme that catalyzes the conversion of S-adenosyl-L-methionine (along with glycine) to S-adenosyl-L-homocysteine and sarcosine. This protein is found in the cytoplasm and acts as a homotetramer. Defects in this gene are a cause of GNMT deficiency (hypermethioninemia). Alternative splicing results in multiple transcript variants. Naturally occurring readthrough transcription occurs between the upstream CNPY3 (canopy FGF signaling regulator 3) gene and this gene and is represented with GeneID:107080644. [provided by RefSeq, Jan 2016]

CNPY3-GNMT (HGNC:):

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.988

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GNMT	NM_018960.6	c.185T>C	p.Leu62Pro	missense_variant	1/6	ENST00000372808.4
CNPY3-GNMT	NR_134890.2	n.340-1810T>C		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GNMT	ENST00000372808.4	c.185T>C	p.Leu62Pro	missense_variant	1/6	1	NM_018960.6	P1

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD3 exomes AF: 0.0000123 AC: 2 AN: 162394 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 89820

Gnomad AFR exome AF: 0.000114

Gnomad AMR exome AF: 0.0000371

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: 7.09e-7 AC: 1 AN: 1410276 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 698216

Gnomad4 AFR exome AF: 0.0000307

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 34

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Aug 14, 2023

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. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt GNMT protein function. This variant has not been reported in the literature in individuals affected with GNMT-related conditions. The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This sequence change replaces leucine, which is neutral and non-polar, with proline, which is neutral and non-polar, at codon 62 of the GNMT protein (p.Leu62Pro). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.46	D
BayesDel_noAF	Pathogenic	0.42
Cadd	Pathogenic	33
Dann	Uncertain	1.0
DEOGEN2	Uncertain	0.72	D
Eigen	Pathogenic	0.90
Eigen_PC	Pathogenic	0.78
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.92	D
M_CAP	Pathogenic	0.91	D
MetaRNN	Pathogenic	0.99	D
MetaSVM	Pathogenic	0.92	D
MutationAssessor	Pathogenic	3.6	H
MutationTaster	Benign	1.0	D
PrimateAI	Pathogenic	0.87	D
PROVEAN	Pathogenic	-6.3	D
REVEL	Pathogenic	0.98
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.95
MutPred		0.91		Loss of stability (P = 0.0575);
MVP		0.99
MPC		2.8
ClinPred		0.99	D
GERP RS		4.6
Varity_R		1.0
gMVP		0.99

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		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: rs1315909137; hg19: chr6-42928690;