rs139890971

Variant names:

Your query was ambiguous. Multiple possible variants found:

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. PP3PM2_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 v4.1.0. is 0.00006674 (5/74922 alleles) in the African African American 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 0.773, in the range of 0.644-0.773, evidence that correlates with impact to GAMT function at the supporting level (PMID:36413997) (PP3). SpliceAI predicts that the variant has no impact on splicing. 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 2.0.0): PP3, PM2_Supporting.(Classification approved by the ClinGen CCDS VCEP on April 28, 2025). 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

Publications

7 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: Uncertain_significance. The variant received 2 ACMG points.

PM2

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

PP3

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.650C>T	p.Pro217Leu	missense_variant	Exon 6 of 6	ENST00000252288.8	NP_000147.1	Q14353-1V9HWB2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
GAMT	ENST00000252288.8 link	c.650C>T	p.Pro217Leu	missense_variant	Exon 6 of 6	1	NM_000156.6	ENSP00000252288.1	Q14353-1
GAMT	ENST00000640762.1 link	c.581C>T	p.Pro194Leu	missense_variant	Exon 6 of 6	5		ENSP00000492031.1	A0A1W2PR36
GAMT	ENST00000640164.1 link	n.483C>T		non_coding_transcript_exon_variant	Exon 4 of 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

GnomAD2 exomes

AF:

0.0000324

AC:

AN:

247244

AF XY:

0.0000223

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 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

African (AFR)

AF:

0.0000299

AC:

AN:

33474

American (AMR)

AF:

0.00

AC:

AN:

44710

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26118

East Asian (EAS)

AF:

0.00

AC:

AN:

39692

South Asian (SAS)

AF:

0.0000464

AC:

AN:

86254

European-Finnish (FIN)

AF:

0.0000196

AC:

AN:

50994

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.0000369

AC:

AN:

1111852

Other (OTH)

AF:

0.0000166

AC:

AN:

60326

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.458

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:

0.0000591

AC:

AN:

152208

Hom.:

Cov.:

AF XY:

0.0000941

AC XY:

AN XY:

74352

show subpopulations

African (AFR)

AF:

0.0000965

AC:

AN:

41448

American (AMR)

AF:

0.00

AC:

AN:

15288

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5196

South Asian (SAS)

AF:

0.00

AC:

AN:

4830

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10624

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000735

AC:

AN:

68032

Other (OTH)

AF:

0.00

AC:

AN:

2090

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.486

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome 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

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

May 31, 2024

GeneDx

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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]) -

Oct 21, 2015

Eurofins Ntd Llc (ga)

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Deficiency of guanidinoacetate methyltransferase

Uncertain:2

Jan 25, 2020

Natera, Inc.

Significance:Uncertain significance

Review Status:no assertion criteria provided

Collection Method:clinical testing

- -

Apr 28, 2025

ClinGen Cerebral Creatine Deficiency Syndromes Variant Curation Expert Panel, ClinGen

Significance:Uncertain significance

Review Status:reviewed by expert panel

Collection Method:curation

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 v4.1.0. is 0.00006674 (5/74922 alleles) in the African African American 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 0.773, in the range of 0.644-0.773, evidence that correlates with impact to GAMT function at the supporting level (PMID: 36413997) (PP3). SpliceAI predicts that the variant has no impact on splicing. 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 2.0.0): PP3, PM2_Supporting. (Classification approved by the ClinGen CCDS VCEP on April 28, 2025). -

Cerebral creatine deficiency syndrome

Uncertain:1

Jan 08, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

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

(source)

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;.

PhyloP100

9.6

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

Mutation Taster

=55/45

polymorphism

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over