NM_000156.6:c.491delG

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM3PP4_StrongPM2_SupportingPVS1_Strong

This summary comes from the ClinGen Evidence Repository: The NM_000156.6:c.491del (p.Gly164AlafsTer14) variant in GAMT is a frameshift variant predicted to cause a premature stop codon in the last 50 nucleotides of the penultimate exon and therefore to escape nonsense mediated decay. More than 10% of the protein is predicted to be removed. (PVS1_Strong). This variant has been detected in in 7 unrelated individuals with GAMT deficiency, all of whom were homozygous for the variant (PMID:29302074, PMID:32214227, PMID:15234333, PMID:23660394, PMID:15108290) (1pt, PM3). One of these individuals had elevated GAA in plasma, elevated GAA in urine, deficient GAMT enzyme activity (<5% wild-type) in fibroblasts, and significantly reduced creatine peak with present GAA peak on brain MRS (PMID:15234333) and one of these individuals had elevated urine GAA and undetectable GAMT enzyme activity in fibroblasts (PMID:15108290) (PP4_Strong). The highest population minor allele frequency in gnomAD v2.1.1 is 0.0001607 (4/24886 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). There is a ClinVar entry for this variant (Variation ID: 810628, 2 star review status) with 7 submitters classifying the variant as pathogenic. In summary, this variant meets the criteria to be classified as pathogenic 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 1.0): PVS1_Strong, PM2_Supporting, PM3, PP4_Strong. (Classification approved by the ClinGen Cerebral Creatine Deficiency Syndromes Variant Curation Expert Panel on May 25, 2023) LINK:https://erepo.genome.network/evrepo/ui/classification/CA9043627/MONDO:0012999/026

Frequency

Genomes: 𝑓 0.000039 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000041 ( 0 hom. )

Consequence

GAMT
NM_000156.6 frameshift

Scores

Not classified

Clinical Significance

Pathogenic reviewed by expert panel P:11

Conservation

PhyloP100: 5.84

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: Pathogenic. The variant received 11 ACMG points.

PVS1

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

PM2

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

PM3

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

PP4

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.491delG	p.Gly164AlafsTer14	frameshift	Exon 5 of 6	NP_000147.1	Q14353-1
	GAMT	NM_138924.3		c.491delG	p.Gly164AlafsTer14	frameshift	Exon 5 of 5	NP_620279.1	Q14353-2

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
GAMT	ENST00000252288.8	TSL:1 MANE Select	c.491delG	p.Gly164AlafsTer14	frameshift	Exon 5 of 6	ENSP00000252288.1	Q14353-1
GAMT	ENST00000902474.1		c.761delG	p.Gly254AlafsTer14	frameshift	Exon 5 of 6	ENSP00000572533.1
GAMT	ENST00000447102.8	TSL:2	c.491delG	p.Gly164AlafsTer14	frameshift	Exon 5 of 5	ENSP00000403536.2	Q14353-2

Frequencies

GnomAD3 genomes

AF:

0.0000394

AC:

AN:

152188

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.000121

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000654

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:

0.0000120

AC:

AN:

250692

AF XY:

0.0000147

show subpopulations

Gnomad AFR exome

AF:

0.000185

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:

0.00

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.00000411

AC:

AN:

1461126

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

726868

show subpopulations

African (AFR)

AF:

0.000119

AC:

AN:

33478

American (AMR)

AF:

0.00

AC:

AN:

44720

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

52712

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

8.99e-7

AC:

AN:

1111970

Other (OTH)

AF:

0.0000166

AC:

AN:

60384

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

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:

0.0000394

AC:

AN:

152188

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74352

show subpopulations

African (AFR)

AF:

0.000121

AC:

AN:

41436

American (AMR)

AF:

0.0000654

AC:

AN:

15286

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5190

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:

0.00

AC:

AN:

68034

Other (OTH)

AF:

0.00

AC:

AN:

2088

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

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:

0.0000227

ClinVar

ClinVar submissions

Significance:Pathogenic

Revision:reviewed by expert panel

View on ClinVar

Pathogenic

VUS

Benign

Condition

Deficiency of guanidinoacetate methyltransferase (6)

Cerebral creatine deficiency syndrome (3)

not provided (2)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

PhyloP100

5.8

Mutation Taster

=0/200

disease causing (ClinVar)

(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

You must be logged in to view publications. This limit was set because tens of millions (!) of queries from AI bots are generated daily.

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