Genetic Variant GAMT:p.Ile73Leu (chr19-1399903-T-G) – ACMG Classification: Uncertain_significance (4 pts)

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM1PM2

The NM_000156.6(GAMT):c.217A>C(p.Ile73Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000131 in 152,172 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I73V) has been classified as Uncertain significance.

Frequency

Genomes: 𝑓 0.000013 ( 0 hom., cov: 32)

Consequence

GAMT
NM_000156.6 missense

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 7.92

Publications

2 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:

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ACMG classification

Classification was made for transcript

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

PM1

In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 8 uncertain in NM_000156.6

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GAMT	NM_000156.6 link	c.217A>C	p.Ile73Leu	missense_variant	Exon 2 of 6	ENST00000252288.8	NP_000147.1	Q14353-1V9HWB2
GAMT	NM_138924.3 link	c.217A>C	p.Ile73Leu	missense_variant	Exon 2 of 5		NP_620279.1	Q14353-2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GAMT	ENST00000252288.8 link	c.217A>C	p.Ile73Leu	missense_variant	Exon 2 of 6	1	NM_000156.6	ENSP00000252288.1		Q14353-1

Frequencies

GnomAD3 genomes

AF:

0.0000131

AC:

AN:

152172

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000483

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

Cov.:

GnomAD4 genome

AF:

0.0000131

AC:

AN:

152172

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74346

show subpopulations

African (AFR)

AF:

0.0000483

AC:

AN:

41442

American (AMR)

AF:

0.00

AC:

AN:

15286

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5184

South Asian (SAS)

AF:

0.00

AC:

AN:

4836

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:

68012

Other (OTH)

AF:

0.00

AC:

AN:

2088

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.600

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.00000378

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.28

BayesDel_addAF

Pathogenic

0.20

BayesDel_noAF

Uncertain

0.050

CADD

Uncertain

(source)

DANN

Uncertain

0.98

DEOGEN2

Benign

0.35

T;.;.

Eigen

Uncertain

0.21

Eigen_PC

Uncertain

0.28

FATHMM_MKL

Pathogenic

0.97

LIST_S2

Uncertain

0.88

D;D;D

M_CAP

Pathogenic

0.35

MetaRNN

Uncertain

0.66

D;D;D

MetaSVM

Uncertain

0.43

MutationAssessor

Uncertain

2.2

M;.;M

PhyloP100

7.9

PrimateAI

Uncertain

0.52

PROVEAN

Benign

-0.84

N;.;N

REVEL

Pathogenic

0.67

Sift

Benign

0.27

T;.;T

Sift4G

Benign

0.58

T;.;T

Polyphen

0.41

B;.;.

Vest4

0.86

MutPred

0.55

Loss of ubiquitination at K77 (P = 0.1453);.;Loss of ubiquitination at K77 (P = 0.1453);

MVP

0.72

MPC

0.22

ClinPred

0.90

GERP RS

4.3

PromoterAI

-0.038

Neutral

(source)

Varity_R

0.37

gMVP

0.67

Mutation Taster

=21/79

disease causing

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.11

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

ClinVar

Computational scores

Splicing

Publications

Other links and lift over