NM_000156.6:c.507_521dupCAACCTCACCTCCTG

Variant names:

• chr19-1398964-C-CCAGGAGGTGAGGTTG
• rs779931959
• NM_000156.6:c.507_521dupCAACCTCACCTCCTG

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PM1 PM4 PP5_Very_Strong

The NM_000156.6(GAMT):​c.507_521dupCAACCTCACCTCCTG​(p.Cys169_Ser173dup) variant causes a disruptive inframe insertion change. The variant allele was found at a frequency of 0.0000112 in 1,613,322 control chromosomes in the GnomAD database, with no homozygous occurrence. It is difficult to determine the true allele frequency of this variant because it is of type INS_BIG, and the frequency of such variant types in population databases may be underestimated and unreliable. Variant has been reported in ClinVar as Likely pathogenic (★★★).

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000012 (0 hom.)
• Consequence: GAMT NM_000156.6 disruptive_inframe_insertion
• Clinical Significance: Likely pathogenic reviewed by expert panel P:6 U:1
• Conservation: PhyloP100: 4.72
• Publications: 0 publications found

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)

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 13 uncertain in NM_000156.6
• PM4: Nonframeshift variant in NON repetitive region in NM_000156.6.
• PP5: Variant 19-1398964-C-CCAGGAGGTGAGGTTG is Pathogenic according to our data. Variant chr19-1398964-C-CCAGGAGGTGAGGTTG is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 431959.Status of the report is reviewed_by_expert_panel, 3 stars.

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.507_521dupCAACCTCACCTCCTG	p.Cys169_Ser173dup	disruptive_inframe_insertion	Exon 5 of 6	NP_000147.1	Q14353-1
	GAMT	NM_138924.3		c.507_521dupCAACCTCACCTCCTG	p.Cys169_Ser173dup	disruptive_inframe_insertion	Exon 5 of 5	NP_620279.1	Q14353-2

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GAMT	ENST00000252288.8	TSL:1 MANE Select	c.507_521dupCAACCTCACCTCCTG	p.Cys169_Ser173dup	disruptive_inframe_insertion	Exon 5 of 6	ENSP00000252288.1	Q14353-1
	GAMT	ENST00000902474.1		c.777_791dupCAACCTCACCTCCTG	p.Cys259_Ser263dup	disruptive_inframe_insertion	Exon 5 of 6	ENSP00000572533.1
	GAMT	ENST00000447102.8	TSL:2	c.507_521dupCAACCTCACCTCCTG	p.Cys169_Ser173dup	disruptive_inframe_insertion	Exon 5 of 5	ENSP00000403536.2	Q14353-2

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152192 Hom.: 0 Cov.: 32

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

GnomAD2 exomes AF: 0.00000399 AC: 1 AN: 250890 AF XY: 0.00000736

Gnomad AFR exome AF: 0.00

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: 0.00000883

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000116 AC: 17 AN: 1461130 Hom.: 0 Cov.: 32 AF XY: 0.0000124 AC XY: 9 AN XY: 726870

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44716

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52700

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.0000153 AC: 17 AN: 1111988

Other (OTH) AF: 0.00 AC: 0 AN: 60386

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152192 Hom.: 0 Cov.: 32 AF XY: 0.0000135 AC XY: 1 AN XY: 74346

African (AFR) AF: 0.00 AC: 0 AN: 41440

American (AMR) AF: 0.00 AC: 0 AN: 15270

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00 AC: 0 AN: 5200

South Asian (SAS) AF: 0.00 AC: 0 AN: 4836

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10624

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.0000147 AC: 1 AN: 68028

Other (OTH) AF: 0.00 AC: 0 AN: 2094

Alfa AF: 0.00 Hom.: 0

ClinVar

ClinVar submissions

Significance: Likely pathogenic

Revision: reviewed by expert panel

Pathogenic	VUS	Benign	Condition
3	-	-	Deficiency of guanidinoacetate methyltransferase (3)
2	-	-	Cerebral creatine deficiency syndrome (2)
-	1	-	Inborn genetic diseases (1)
1	-	-	not provided (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		4.7
Mutation Taster		=31/69	disease causing (ClinVar)

Splicing

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

Other links and lift over

dbSNP: rs779931959; hg19: chr19-1398963;