NM_000156.6:c.650C>T

Variant names:

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: Ambry Genetics, Orphanet, G2P, ClinGen, Labcorp Genetics (formerly Invitae)

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.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000156.6. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GAMT	NM_000156.6	MANE Select	c.650C>T	p.Pro217Leu	missense	Exon 6 of 6	NP_000147.1	Q14353-1

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
GAMT	ENST00000252288.8	TSL:1 MANE Select	c.650C>T	p.Pro217Leu	missense	Exon 6 of 6	ENSP00000252288.1	Q14353-1
GAMT	ENST00000902474.1		c.920C>T	p.Pro307Leu	missense	Exon 6 of 6	ENSP00000572533.1
GAMT	ENST00000902472.1		c.653C>T	p.Pro218Leu	missense	Exon 6 of 6	ENSP00000572531.1

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

ClinVar submissions

Significance:Uncertain significance

Revision:reviewed by expert panel

View on ClinVar

Pathogenic

VUS

Benign

Condition

Deficiency of guanidinoacetate methyltransferase (2)

not provided (2)

Cerebral creatine deficiency syndrome (1)

Computational scores

Source: dbNSFP v4.9

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

Eigen

Pathogenic

0.70

Eigen_PC

Uncertain

0.62

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.86

M_CAP

Uncertain

0.21

MetaRNN

Pathogenic

0.92

MetaSVM

Uncertain

0.67

MutationAssessor

Pathogenic

3.2

PhyloP100

9.6

PROVEAN

Pathogenic

-6.1

REVEL

Pathogenic

0.74

Sift

Uncertain

0.0010

Sift4G

Uncertain

0.0030

Polyphen

1.0

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

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over