rs139890971

Positions:

Variant summary

Our verdict is Uncertain significance. Variant got 1 ACMG points: 1P and 0B. PM2_Supporting

This summary comes from the ClinGen Evidence Repository: The NM_000156.6:c.650C>T variant in GAMT is a missense variant predicted to result in the substitution of proline for leucine at amino acid 217 (p.Pro217Leu). The highest population minor allele frequency in gnomAD v2.1.1 is 0.00008 (2/24536 alleles) in the African population, which is lower than the ClinGen CCDS VCEP’s threshold for PM2_Supporting (<0.0004), meeting this criterion (PM2_Supporting). The computational predictor REVEL gives a score of 0.745 which is neither above nor below the thresholds predicting a damaging (>0.75) or benign (<0.5) impact on GAMT function. To our knowledge, this variant has not been reported in published literature in individuals with GAMT deficiency, and the results of functional studies are unavailable. This variant has been previously reported in ClinVar (Variation ID: 205592). In summary, this variant meets the criteria to be classified as a variant of uncertain significance for GAMT deficiency. GAMT-specific ACMG/AMP codes met, as specified by the ClinGen Cerebral Creatine Deficiency Syndromes VCEP (Specifications Version 1.1.0): PM2_Supporting.(Classification approved by the ClinGen CCDS VCEP on June 6, 2022). LINK:https://erepo.genome.network/evrepo/ui/classification/CA314828/MONDO:0012999/026

Frequency

Genomes: 𝑓 0.000059 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000033 ( 0 hom. )

Consequence

GAMT
NM_000156.6 missense

Scores

Clinical Significance

Uncertain significance reviewed by expert panel U:5

Conservation

PhyloP100: 9.63

Variant links:

Genes affected

GAMT (HGNC:4136): (guanidinoacetate N-methyltransferase) The protein encoded by this gene is a methyltransferase that converts guanidoacetate to creatine, using S-adenosylmethionine as the methyl donor. Defects in this gene have been implicated in neurologic syndromes and muscular hypotonia, probably due to creatine deficiency and accumulation of guanidinoacetate in the brain of affected individuals. Two transcript variants encoding different isoforms have been described for this gene. Pseudogenes of this gene are found on chromosomes 2 and 13. [provided by RefSeq, Feb 2012]

GAMT links:

GAMT (HGNC:):

GAMT links:

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ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 1 ACMG points.

PM2

For more information check the summary or visit ClinGen Evidence Repository.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GAMT	NM_000156.6 linkuse as main transcript	c.650C>T	p.Pro217Leu	missense_variant	6/6	ENST00000252288.8	NP_000147.1	Q14353-1V9HWB2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	UniProt
GAMT	ENST00000252288.8 linkuse as main transcript	c.650C>T	p.Pro217Leu	missense_variant	6/6	1	NM_000156.6	ENSP00000252288.1	Q14353-1
GAMT	ENST00000640762.1 linkuse as main transcript	c.581C>T	p.Pro194Leu	missense_variant	6/6	5		ENSP00000492031.1	A0A1W2PR36
GAMT	ENST00000640164.1 linkuse as main transcript	n.483C>T		non_coding_transcript_exon_variant	4/4	2

Frequencies

GnomAD3 genomes

AF:

0.0000591

AC:

AN:

152208

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000965

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000735

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000324

AC:

AN:

247244

Hom.:

AF XY:

0.0000223

AC XY:

AN XY:

134410

show subpopulations

Gnomad AFR exome

AF:

0.000126

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.0000327

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000446

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000329

AC:

AN:

1459186

Hom.:

Cov.:

AF XY:

0.0000317

AC XY:

AN XY:

725938

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.0000464

Gnomad4 FIN exome

AF:

0.0000196

Gnomad4 NFE exome

AF:

0.0000369

Gnomad4 OTH exome

AF:

0.0000166

GnomAD4 genome

AF:

0.0000591

AC:

AN:

152208

Hom.:

Cov.:

AF XY:

0.0000941

AC XY:

AN XY:

74352

show subpopulations

Gnomad4 AFR

AF:

0.0000965

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.0000735

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000350

Hom.:

Bravo

AF:

0.0000680

ExAC

AF:

0.0000330

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: reviewed by expert panel

LINK: link

Submissions by phenotype

not provided

Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	May 31, 2024	Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published in a peer reviewed journal to our knowledge; This variant is associated with the following publications: (PMID: Di Muro2019[Thesis]) -
Uncertain significance, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Oct 21, 2015	- -

Deficiency of guanidinoacetate methyltransferase

Uncertain:2

Uncertain significance, no assertion criteria provided	clinical testing	Natera, Inc.	Jan 25, 2020	- -
Uncertain significance, reviewed by expert panel	curation	ClinGen Cerebral Creatine Deficiency Syndromes Variant Curation Expert Panel, ClinGen	Jun 06, 2022	The NM_000156.6:c.650C>T variant in GAMT is a missense variant predicted to result in the substitution of proline for leucine at amino acid 217 (p.Pro217Leu). The highest population minor allele frequency in gnomAD v2.1.1 is 0.00008 (2/24536 alleles) in the African population, which is lower than the ClinGen CCDS VCEP’s threshold for PM2_Supporting (<0.0004), meeting this criterion (PM2_Supporting). The computational predictor REVEL gives a score of 0.745 which is neither above nor below the thresholds predicting a damaging (>0.75) or benign (<0.5) impact on GAMT function. To our knowledge, this variant has not been reported in published literature in individuals with GAMT deficiency, and the results of functional studies are unavailable. This variant has been previously reported in ClinVar (Variation ID: 205592). In summary, this variant meets the criteria to be classified as a variant of uncertain significance for GAMT deficiency. GAMT-specific ACMG/AMP codes met, as specified by the ClinGen Cerebral Creatine Deficiency Syndromes VCEP (Specifications Version 1.1.0): PM2_Supporting. (Classification approved by the ClinGen CCDS VCEP on June 6, 2022). -

Cerebral creatine deficiency syndrome

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 08, 2024

This sequence change replaces proline, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 217 of the GAMT protein (p.Pro217Leu). This variant is present in population databases (rs139890971, gnomAD 0.008%). This variant has not been reported in the literature in individuals affected with GAMT-related conditions. ClinVar contains an entry for this variant (Variation ID: 205592). 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on GAMT protein function. 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

AlphaMissense

Uncertain

0.43

BayesDel_addAF

Pathogenic

0.16

BayesDel_noAF

Pathogenic

0.23

CADD

Pathogenic

DANN

Uncertain

1.0

DEOGEN2

Uncertain

0.74

D;.

Eigen

Pathogenic

0.70

Eigen_PC

Uncertain

0.62

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.86

D;D

M_CAP

Uncertain

0.21

MetaRNN

Pathogenic

0.92

D;D

MetaSVM

Uncertain

0.67

MutationAssessor

Pathogenic

3.2

M;.

PROVEAN

Pathogenic

-6.1

D;.

REVEL

Pathogenic

0.74

Sift

Uncertain

0.0010

D;.

Sift4G

Uncertain

0.0030

D;.

Polyphen

1.0

D;.

Vest4

0.77

MVP

0.97

ClinPred

0.42

GERP RS

5.1

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.68

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

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

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over