19-1397270-G-T

Variant summary

Our verdict is Benign. Variant got -16 ACMG points: 0P and 16B. BP4_Strong BP6_Very_Strong BS1

The NM_000156.6(GAMT):c.*89C>A variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000816 in 1,455,866 control chromosomes in the GnomAD database, including 3 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★).

• Frequency:
  • Genomes: 𝑓 0.0033 (1 hom., cov: 33)
  • Exomes 𝑓: 0.00052 (2 hom.)
• Consequence: GAMT NM_000156.6 3_prime_UTR
• Clinical Significance: Likely benign criteria provided, multiple submitters, no conflicts B:2
• Conservation: PhyloP100: -0.101

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]

ACMG classification

Verdict is Benign. Variant got -16 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.88).
• BP6: Variant 19-1397270-G-T is Benign according to our data. Variant chr19-1397270-G-T is described in ClinVar as [Likely_benign]. Clinvar id is 889369.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BS1: Variant frequency is greater than expected in population afr. gnomad4 allele frequency = 0.00331 (504/152310) while in subpopulation AFR AF= 0.0105 (435/41558). AF 95% confidence interval is 0.00965. There are 1 homozygotes in gnomad4. There are 252 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GAMT	NM_000156.6	c.*89C>A		3_prime_UTR_variant	6/6	ENST00000252288.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GAMT	ENST00000252288.8	c.*89C>A		3_prime_UTR_variant	6/6	1	NM_000156.6	P1
GAMT	ENST00000640762.1	c.*89C>A		3_prime_UTR_variant	6/6	5

Frequencies

GnomAD3 genomes AF: 0.00331 AC: 503 AN: 152192 Hom.: 1 Cov.: 33

Gnomad AFR AF: 0.0105

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00275

Gnomad ASJ AF: 0.00144

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00633

Gnomad NFE AF: 0.000176

Gnomad OTH AF: 0.00335

GnomAD4 exome AF: 0.000525 AC: 684 AN: 1303556 Hom.: 2 Cov.: 21 AF XY: 0.000470 AC XY: 303 AN XY: 644594

Gnomad4 AFR exome AF: 0.00980

Gnomad4 AMR exome AF: 0.00178

Gnomad4 ASJ exome AF: 0.00183

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.000206

Gnomad4 OTH exome AF: 0.00122

GnomAD4 genome AF: 0.00331 AC: 504 AN: 152310 Hom.: 1 Cov.: 33 AF XY: 0.00338 AC XY: 252 AN XY: 74480

Gnomad4 AFR AF: 0.0105

Gnomad4 AMR AF: 0.00274

Gnomad4 ASJ AF: 0.00144

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000176

Gnomad4 OTH AF: 0.00331

Alfa AF: 0.00354 Hom.: 0

Bravo AF: 0.00364

Asia WGS AF: 0.000289 AC: 1 AN: 3478

ClinVar

Significance: Likely benign

Submissions summary: Benign:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Benign:1

Likely benign, criteria provided, single submitter

clinical testing

GeneDx

Jul 26, 2018

- -

Deficiency of guanidinoacetate methyltransferase Benign:1

Likely benign, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.88
Cadd	Benign	2.6
Dann	Benign	0.74
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1

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

LitVar

Other links and lift over

dbSNP: rs558767159; hg19: chr19-1397269;