19-1399938-C-T

Variant names:

Variant summary

Our verdict is Benign. Variant got -8 ACMG points: 0P and 8B. BA1

This summary comes from the ClinGen Evidence Repository: The NM_000156.6:c.182G>A variant in GAMT is a missense variant that is predicted to cause the substitution of a glycine by a glutamate at amino acid position 61 (p.Gly61Glu). To our knowledge, this variant has not been reported among individuals with GAMT deficiency and results of functional studies are unavailable. The GrpMax filtering allele frequency (95% confidence) in gnomAD v4.1.0. is 0.01102 in the East Asian population, including 6 homozygotes. This is higher than the ClinGen CCDS VCEP threshold for BA1 (>0.003), meeting this criterion (BA1). There is a ClinVar entry for this variant (Variation ID: 328350). In summary, this variant meets the criteria to be classified as benign for GAMT deficiency based on the ACMG/AMP criteria applied, as specified by the ClinGen Cerebral Creatine Deficiency Syndromes Variant Curation Expert Panel (Specifications Version 2.0.0): BA1.(Classification approved by the ClinGen Cerebral Creatine Deficiencies Variant Curation Expert Panel on March 18, 2025) LINK:https://erepo.genome.network/evrepo/ui/classification/CA9043773/MONDO:0012999/026

Frequency

Genomes: 𝑓 0.00014 ( 1 hom., cov: 32)

Exomes 𝑓: 0.00036 ( 5 hom. )

Consequence

GAMT
NM_000156.6 missense, splice_region

Scores

Splicing: ADA: 0.9948

Clinical Significance

Benign reviewed by expert panel U:4B:2

Conservation

PhyloP100: 7.58

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:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Benign. Variant got -8 ACMG points.

BA1

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

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GAMT	NM_000156.6 link	c.182G>A	p.Gly61Glu	missense_variant, splice_region_variant	Exon 2 of 6	ENST00000252288.8	NP_000147.1	Q14353-1V9HWB2
GAMT	NM_138924.3 link	c.182G>A	p.Gly61Glu	missense_variant, splice_region_variant	Exon 2 of 5		NP_620279.1	Q14353-2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GAMT	ENST00000252288.8 link	c.182G>A	p.Gly61Glu	missense_variant, splice_region_variant	Exon 2 of 6	1	NM_000156.6	ENSP00000252288.1		Q14353-1

Frequencies

GnomAD3 genomes

AF:

0.000138

AC:

AN:

152206

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00405

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.000116

AC:

AN:

232624

Hom.:

AF XY:

0.0000869

AC XY:

AN XY:

126550

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00142

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.000351

GnomAD4 exome

AF:

0.000355

AC:

516

AN:

1453434

Hom.:

Cov.:

AF XY:

0.000352

AC XY:

254

AN XY:

722390

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.0129

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00

Gnomad4 OTH exome

AF:

0.000133

GnomAD4 genome

AF:

0.000138

AC:

AN:

152322

Hom.:

Cov.:

AF XY:

0.000228

AC XY:

AN XY:

74482

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00406

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000231

Hom.:

Bravo

AF:

0.0000227

ExAC

AF:

0.000199

AC:

Asia WGS

AF:

0.00144

AC:

AN:

3478

ClinVar

Significance: Benign

Submissions summary: Uncertain:4Benign:2

Revision: reviewed by expert panel

LINK: link

Submissions by phenotype

Deficiency of guanidinoacetate methyltransferase

Uncertain:2Benign:2

Jan 07, 2020

Natera, Inc.

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Apr 15, 2024

Fulgent Genetics, Fulgent Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Mar 18, 2025

ClinGen Cerebral Creatine Deficiency Syndromes Variant Curation Expert Panel, ClinGen

Significance: Benign

Review Status: reviewed by expert panel

Collection Method: curation

The NM_000156.6:c.182G>A variant in GAMT is a missense variant that is predicted to cause the substitution of a glycine by a glutamate at amino acid position 61 (p.Gly61Glu). To our knowledge, this variant has not been reported among individuals with GAMT deficiency and results of functional studies are unavailable. The GrpMax filtering allele frequency (95% confidence) in gnomAD v4.1.0. is 0.01102 in the East Asian population, including 6 homozygotes. This is higher than the ClinGen CCDS VCEP threshold for BA1 (>0.003), meeting this criterion (BA1). There is a ClinVar entry for this variant (Variation ID: 328350). In summary, this variant meets the criteria to be classified as benign for GAMT deficiency based on the ACMG/AMP criteria applied, as specified by the ClinGen Cerebral Creatine Deficiency Syndromes Variant Curation Expert Panel (Specifications Version 2.0.0): BA1. (Classification approved by the ClinGen Cerebral Creatine Deficiencies Variant Curation Expert Panel on March 18, 2025) -

Jan 12, 2018

Illumina Laboratory Services, Illumina

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

not provided

Uncertain:1

Jun 10, 2020

GeneDx

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

Cerebral creatine deficiency syndrome

Uncertain:1

Jun 03, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine, which is neutral and non-polar, with glutamic acid, which is acidic and polar, at codon 61 of the GAMT protein (p.Gly61Glu). This variant is present in population databases (rs77168423, gnomAD 0.2%). 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: 328350). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. 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

Pathogenic

0.61

BayesDel_addAF

Benign

-0.13

BayesDel_noAF

Uncertain

0.030

CADD

Pathogenic

DANN

Uncertain

1.0

DEOGEN2

Uncertain

0.77

D;.;.

Eigen

Uncertain

0.59

Eigen_PC

Uncertain

0.54

FATHMM_MKL

Pathogenic

0.98

LIST_S2

Uncertain

0.88

D;T;D

M_CAP

Pathogenic

0.45

MetaRNN

Benign

0.042

T;T;T

MetaSVM

Uncertain

0.59

MutationAssessor

Uncertain

2.0

M;.;M

PrimateAI

Uncertain

0.71

PROVEAN

Pathogenic

-6.9

D;.;D

REVEL

Pathogenic

0.76

Sift

Uncertain

0.0020

D;.;T

Sift4G

Pathogenic

0.0

D;.;D

Polyphen

1.0

D;.;.

Vest4

0.74

MVP

0.97

MPC

0.37

ClinPred

0.32

GERP RS

4.0

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.8

Varity_R

0.92

gMVP

0.64

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

0.99

dbscSNV1_RF

Pathogenic

0.86

SpliceAI score (max)

0.13

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