chr19-1397381-G-A

Variant names:

Variant summary

Our verdict is Uncertain significance. The variant received 1 ACMG points: 1P and 0B. PM2_Supporting

This summary comes from the ClinGen Evidence Repository: The NM_000156.6:c.689C>T variant in GAMT is a missense variant in exon 6, predicted to result in the substitution of threonine for methionine at amino acid 230 (p.Thr230Met). The highest population minor allele frequency in gnomAD v4.1.0. is 0.00008784 (8/91070 alleles) in the South Asian 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 0.48 which is neither above nor below the thresholds predicting a damaging (>0.644) or benign (<0.29) impact on GAMT function. 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: 205595). 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): PM2_Supporting(Classification approved by the ClinGen CCDS VCEP on April 25, 2025). LINK:https://erepo.genome.network/evrepo/ui/classification/CA314834/MONDO:0012999/026

Frequency

Genomes: 𝑓 0.000020 ( 0 hom., cov: 33)

Exomes 𝑓: 0.000014 ( 0 hom. )

Consequence

GAMT
NM_000156.6 missense

Scores

Clinical Significance

Uncertain significance reviewed by expert panel U:4

Conservation

PhyloP100: 4.01

Publications

1 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 1 ACMG points.

PM2

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.689C>T	p.Thr230Met	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.689C>T	p.Thr230Met	missense	Exon 6 of 6	ENSP00000252288.1	Q14353-1
GAMT	ENST00000902474.1		c.959C>T	p.Thr320Met	missense	Exon 6 of 6	ENSP00000572533.1
GAMT	ENST00000902472.1		c.692C>T	p.Thr231Met	missense	Exon 6 of 6	ENSP00000572531.1

Frequencies

GnomAD3 genomes

AF:

0.0000197

AC:

AN:

152196

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000654

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000202

AC:

AN:

247276

AF XY:

0.0000223

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000290

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000144

AC:

AN:

1459988

Hom.:

Cov.:

AF XY:

0.0000193

AC XY:

AN XY:

726330

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

33472

American (AMR)

AF:

0.0000448

AC:

AN:

44678

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26100

East Asian (EAS)

AF:

0.00

AC:

AN:

39686

South Asian (SAS)

AF:

0.0000812

AC:

AN:

86232

European-Finnish (FIN)

AF:

0.00

AC:

AN:

51912

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

0.0000108

AC:

AN:

1111790

Other (OTH)

AF:

0.00

AC:

AN:

60352

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.473

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:

0.0000197

AC:

AN:

152196

Hom.:

Cov.:

AF XY:

0.0000134

AC XY:

AN XY:

74350

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41436

American (AMR)

AF:

0.0000654

AC:

AN:

15292

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5192

South Asian (SAS)

AF:

0.000207

AC:

AN:

4838

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10628

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

68020

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

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:

0.00

Hom.:

Bravo

AF:

0.00000756

ExAC

AF:

0.0000248

AC:

ClinVar

ClinVar submissions

Significance:Uncertain significance

Revision:reviewed by expert panel

View on ClinVar

Pathogenic

VUS

Benign

Condition

Deficiency of guanidinoacetate methyltransferase (2)

Cerebral creatine deficiency syndrome (1)

not provided (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.12

BayesDel_addAF

Benign

-0.020

BayesDel_noAF

Uncertain

-0.030

CADD

Uncertain

(source)

DANN

Pathogenic

1.0

DEOGEN2

Benign

0.39

Eigen

Uncertain

0.48

Eigen_PC

Uncertain

0.44

FATHMM_MKL

Uncertain

0.95

LIST_S2

Benign

0.79

M_CAP

Uncertain

0.22

MetaRNN

Uncertain

0.50

MetaSVM

Uncertain

0.42

MutationAssessor

Uncertain

2.6

PhyloP100

4.0

PROVEAN

Benign

-1.3

REVEL

Uncertain

0.48

Sift

Uncertain

0.017

Sift4G

Uncertain

0.0080

Polyphen

1.0

Vest4

0.69

MutPred

0.21

Gain of helix (P = 0.0696)

MVP

0.94

ClinPred

0.46

GERP RS

4.0

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.7

Varity_R

0.31

Mutation Taster

=52/48

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

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over