NM_000156.6:c.189G>C

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 0P and 2B. BP7BP4

This summary comes from the ClinGen Evidence Repository: The NM_000156.6:c.189G>C (p.Arg63=) variant in GAMT is a synonymous (silent) variant that is not predicted by SpliceAI to impact splicing. In addition, it occurs at a nucleotide that is not conserved as shown by phyloP (score -1.308) (BP4, BP7). To our knowledge, this variant has not been reported among individuals with GAMT deficiency and results of functional studies are unavailable. The highest population minor allele frequency in gnomAD v4.1.0 is 0.0004955 (3/6054) in the Middle Eastern population. This is higher than the ClinGen CCDS VCEP's threshold for PM2_Supporting (<0.0004), and lower than the threshold for BS1 (>0.001). Therefore, no population criteria are met. There is a ClinVar entry for this variant (Variation ID: 288963). In summary, this variant meets the criteria to be classified as likely 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): BP4, BP7.(Classification approved by the ClinGen Cerebral Creatine Deficiency Syndromes Variant Curation Expert Panel on May 20, 2025). LINK:https://erepo.genome.network/evrepo/ui/classification/CA9043767/MONDO:0012999/026

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000022 ( 0 hom. )

Consequence

GAMT
NM_000156.6 synonymous

Scores

Clinical Significance

Likely benign reviewed by expert panel U:2B:5

Conservation

PhyloP100: -1.24

Publications

0 publications found

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 Gene-Disease associations (from GenCC):

guanidinoacetate methyltransferase deficiency
Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, G2P, Labcorp Genetics (formerly Invitae), ClinGen, Ambry Genetics

GAMT links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -2 ACMG points.

BP4

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

BP7

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.189G>C	p.Arg63Arg	synonymous_variant	Exon 2 of 6	ENST00000252288.8	NP_000147.1	Q14353-1V9HWB2
GAMT	NM_138924.3 link	c.189G>C	p.Arg63Arg	synonymous_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.189G>C	p.Arg63Arg	synonymous_variant	Exon 2 of 6	1	NM_000156.6	ENSP00000252288.1		Q14353-1

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152232

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000482

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:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000213

AC:

AN:

235050

AF XY:

0.0000235

show subpopulations

Gnomad AFR exome

AF:

0.0000687

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00000945

Gnomad OTH exome

AF:

0.000174

GnomAD4 exome

AF:

0.0000220

AC:

AN:

1454706

Hom.:

Cov.:

AF XY:

0.0000304

AC XY:

AN XY:

723122

show subpopulations

African (AFR)

AF:

0.000718

AC:

AN:

33406

American (AMR)

AF:

0.00

AC:

AN:

44022

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25960

East Asian (EAS)

AF:

0.00

AC:

AN:

39482

South Asian (SAS)

AF:

0.0000235

AC:

AN:

85036

European-Finnish (FIN)

AF:

0.00

AC:

AN:

51064

Middle Eastern (MID)

AF:

0.000521

AC:

AN:

5760

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1109828

Other (OTH)

AF:

0.0000499

AC:

AN:

60148

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.467

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152350

Hom.:

Cov.:

AF XY:

0.0000134

AC XY:

AN XY:

74510

show subpopulations

African (AFR)

AF:

0.0000481

AC:

AN:

41584

American (AMR)

AF:

0.00

AC:

AN:

15308

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5182

South Asian (SAS)

AF:

0.00

AC:

AN:

4826

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10630

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68028

Other (OTH)

AF:

0.00

AC:

AN:

2114

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.500

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.0000508

Hom.:

Bravo

AF:

0.00000378

ClinVar

Significance: Likely benign

Submissions summary: Uncertain:2Benign:5

Revision: reviewed by expert panel

LINK: link

Submissions by phenotype

not provided

Uncertain:1Benign:1

Jul 01, 2024

CeGaT Center for Human Genetics Tuebingen

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

GAMT: BP4, BP7 -

Jul 15, 2016

Eurofins Ntd Llc (ga)

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Deficiency of guanidinoacetate methyltransferase

Uncertain:1Benign:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance:Uncertain significance

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, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

May 20, 2025

ClinGen Cerebral Creatine Deficiency Syndromes Variant Curation Expert Panel, ClinGen

Significance:Likely benign

Review Status:reviewed by expert panel

Collection Method:curation

The NM_000156.6:c.189G>C (p.Arg63=) variant in GAMT is a synonymous (silent) variant that is not predicted by SpliceAI to impact splicing. In addition, it occurs at a nucleotide that is not conserved as shown by phyloP (score -1.308) (BP4, BP7). To our knowledge, this variant has not been reported among individuals with GAMT deficiency and results of functional studies are unavailable. The highest population minor allele frequency in gnomAD v4.1.0 is 0.0004955 (3/6054) in the Middle Eastern population. This is higher than the ClinGen CCDS VCEP's threshold for PM2_Supporting (<0.0004), and lower than the threshold for BS1 (>0.001). Therefore, no population criteria are met. There is a ClinVar entry for this variant (Variation ID: 288963). In summary, this variant meets the criteria to be classified as likely 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): BP4, BP7. (Classification approved by the ClinGen Cerebral Creatine Deficiency Syndromes Variant Curation Expert Panel on May 20, 2025). -

not specified

Benign:1

Dec 27, 2017

GeneDx

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease. -

Inborn genetic diseases

Benign:1

Dec 23, 2016

Ambry Genetics

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This alteration is classified as likely benign based on a combination of the following: seen in unaffected individuals, population frequency, intact protein function, lack of segregation with disease, co-occurrence, RNA analysis, in silico models, amino acid conservation, lack of disease association in case-control studies, and/or the mechanism of disease or impacted region is inconsistent with a known cause of pathogenicity. -

Cerebral creatine deficiency syndrome

Benign:1

Jan 06, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.56

CADD

Benign

4.6

(source)

DANN

Benign

0.77

PhyloP100

-1.2

PromoterAI

0.018

Neutral

(source)

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

3.1

Mutation Taster

=100/0

polymorphism

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over