rs141471799

Positions:

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 4P and 1B. PM1PM2BP4

The NM_000156.6(GAMT):c.670G>C(p.Ala224Pro) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000124 in 1,612,350 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. A224T) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.0000066 ( 0 hom., cov: 33)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

GAMT
NM_000156.6 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:2

Conservation

PhyloP100: 0.304

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 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 3 ACMG points.

PM1

In a domain RMT2 (size 223) in uniprot entity GAMT_HUMAN there are 70 pathogenic changes around while only 17 benign (80%) in NM_000156.6

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (MetaRNN=0.41432855).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GAMT	NM_000156.6 linkuse as main transcript	c.670G>C	p.Ala224Pro	missense_variant	6/6	ENST00000252288.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GAMT	ENST00000252288.8 linkuse as main transcript	c.670G>C	p.Ala224Pro	missense_variant	6/6	1	NM_000156.6	P1	Q14353-1
GAMT	ENST00000640762.1 linkuse as main transcript	c.601G>C	p.Ala201Pro	missense_variant	6/6	5
GAMT	ENST00000640164.1 linkuse as main transcript	n.503G>C		non_coding_transcript_exon_variant	4/4	2

Frequencies

GnomAD3 genomes

AF:

0.00000657

AC:

AN:

152186

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

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

GnomAD4 exome

AF:

6.85e-7

AC:

AN:

1460164

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

726402

show subpopulations

Gnomad4 AFR exome

AF:

0.0000299

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00

Gnomad4 OTH exome

AF:

0.00

GnomAD4 genome

AF:

0.00000657

AC:

AN:

152186

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74342

show subpopulations

Gnomad4 AFR

AF:

0.0000241

Gnomad4 AMR

AF:

0.00

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Inborn genetic diseases

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 27, 2023

The c.670G>C (p.A224P) alteration is located in exon 6 (coding exon 6) of the GAMT gene. This alteration results from a G to C substitution at nucleotide position 670, causing the alanine (A) at amino acid position 224 to be replaced by a proline (P). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Cerebral creatine deficiency syndrome

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 13, 2023

This sequence change replaces alanine, which is neutral and non-polar, with proline, which is neutral and non-polar, at codon 224 of the GAMT protein (p.Ala224Pro). This variant is not present in population databases (gnomAD no frequency). 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: 1382565). 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) performed at Invitae indicates that this missense variant is not expected to disrupt 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

0.35

BayesDel_addAF

Uncertain

0.037

BayesDel_noAF

Benign

-0.18

CADD

Benign

DANN

Uncertain

0.99

DEOGEN2

Benign

0.32

T;.

Eigen

Benign

-0.69

Eigen_PC

Benign

-0.69

FATHMM_MKL

Benign

0.56

LIST_S2

Benign

0.76

T;T

M_CAP

Uncertain

0.091

MetaRNN

Benign

0.41

T;T

MetaSVM

Benign

-0.84

MutationAssessor

Benign

1.6

L;.

MutationTaster

Benign

0.51

PROVEAN

Benign

-1.0

N;.

REVEL

Uncertain

0.42

Sift

Benign

0.21

T;.

Sift4G

Benign

0.12

T;.

Polyphen

0.56

P;.

Vest4

0.15

MutPred

0.40

Gain of helix (P = 0.132);.;

MVP

0.82

ClinPred

0.74

GERP RS

-3.6

Varity_R

0.55

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.020

Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over