Genetic Variant GAMT:c.*311C>T (chr19-1397048-G-A) – ACMG Classification: Likely_benign (-2 pts)

Variant summary

Our verdict is Likely benign. The variant received -2 ACMG points: 2P and 4B. PM2BP4_Strong

The NM_000156.6(GAMT):c.*311C>T variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000132 in 379,396 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

Frequency

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

Exomes 𝑓: 0.000018 ( 0 hom. )

Consequence

GAMT
NM_000156.6 3_prime_UTR

Scores

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: -0.941

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

GAMT links:

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ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -2 ACMG points.

PM2

Very rare variant in population databases, with high coverage;

BP4

Computational evidence support a benign effect (BayesDel_noAF=-0.86).

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.*311C>T		3_prime_UTR	Exon 6 of 6	NP_000147.1	Q14353-1

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	Effect	Exon Rank	Protein	UniProt
GAMT	ENST00000252288.8	TSL:1 MANE Select	c.*311C>T	3_prime_UTR	Exon 6 of 6	ENSP00000252288.1	Q14353-1
GAMT	ENST00000902474.1		c.*311C>T	downstream_gene	N/A	ENSP00000572533.1
GAMT	ENST00000902472.1		c.*311C>T	downstream_gene	N/A	ENSP00000572531.1

Frequencies

GnomAD3 genomes

AF:

0.00000658

AC:

AN:

152090

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD4 exome

AF:

0.0000176

AC:

AN:

227306

Hom.:

Cov.:

AF XY:

0.0000168

AC XY:

AN XY:

118794

show subpopulations

African (AFR)

AF:

0.000132

AC:

AN:

7564

American (AMR)

AF:

0.00

AC:

AN:

11436

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

7208

East Asian (EAS)

AF:

0.00

AC:

AN:

14324

South Asian (SAS)

AF:

0.0000382

AC:

AN:

26208

European-Finnish (FIN)

AF:

0.00

AC:

AN:

12658

Middle Eastern (MID)

AF:

0.00

AC:

AN:

1020

European-Non Finnish (NFE)

AF:

0.0000150

AC:

AN:

133570

Other (OTH)

AF:

0.00

AC:

AN:

13318

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.413

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

AF:

0.00000658

AC:

AN:

152090

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74302

show subpopulations

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

41358

American (AMR)

AF:

0.00

AC:

AN:

15282

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5192

South Asian (SAS)

AF:

0.00

AC:

AN:

4832

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10632

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

68006

Other (OTH)

AF:

0.00

AC:

AN:

2088

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.275

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.00

Hom.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

BayesDel_noAF

Benign

-0.86

CADD

Benign

3.7

(source)

DANN

Benign

0.96

PhyloP100

-0.94

Splicing

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

ClinVar

Computational scores

Splicing

Publications

Other links and lift over