3-49422132-G-T

Variant names:

• chr3-49422132-G-T
• NM_000481.4:c.230C>A

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_000481.4(AMT):​c.230C>A​(p.Ser77*) variant causes a stop gained change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 32)
• Consequence: AMT NM_000481.4 stop_gained
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 9.39

Genes affected

AMT (HGNC:473): (aminomethyltransferase) This gene encodes one of four critical components of the glycine cleavage system. Mutations in this gene have been associated with glycine encephalopathy. Multiple transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Sep 2011]

ENSG00000283189 (HGNC:):

NICN1 (HGNC:18317): (nicolin 1, tubulin polyglutamylase complex subunit) This protein encoded by this gene localizes to the nucleus and is expressed in numerous tissues including brain, testis, liver, and kidney. This refseq contains genomic sequence in its 3' UTR which is not supported by experimental evidence. Computer predictions indicate that this region of the 3' UTR contains hairpin-forming self-complementary sequence which is possibly excised after transcription. This gene has a pseudogene on chromosome X. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 3-49422132-G-T is Pathogenic according to our data. Variant chr3-49422132-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1343486.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
AMT	NM_000481.4	c.230C>A	p.Ser77*	stop_gained	Exon 2 of 9	ENST00000273588.9	NP_000472.2
NICN1	NM_032316.3	c.*2701C>A		downstream_gene_variant		ENST00000273598.8	NP_115692.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
AMT	ENST00000273588.9	c.230C>A	p.Ser77*	stop_gained	Exon 2 of 9	1	NM_000481.4	ENSP00000273588.3
ENSG00000283189	ENST00000636166.1	c.496-560C>A		intron_variant	Intron 4 of 10	5		ENSP00000490106.1
NICN1	ENST00000273598.8	c.*2701C>A		downstream_gene_variant		1	NM_032316.3	ENSP00000273598.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Glycine encephalopathy Pathogenic:1

Feb 21, 2022

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: AMT c.230C>A (p.Ser77X) results in a premature termination codon, predicted to cause a truncation of the encoded protein or absence of the protein due to nonsense mediated decay, which are commonly known mechanisms for disease. Truncations downstream of this position have been classified as pathogenic by our laboratory. The variant was absent in 251186 control chromosomes (gnomAD). To our knowledge, no occurrence of c.230C>A in individuals affected with Glycine Encephalopathy (Non-Ketotic Hyperglycinemia) and no experimental evidence demonstrating its impact on protein function have been reported. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014. Based on the evidence outlined above, the variant was classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.62	D
BayesDel_noAF	Pathogenic	0.54
CADD	Pathogenic	39
DANN	Uncertain	0.99
Eigen	Uncertain	0.61
Eigen_PC	Uncertain	0.38
FATHMM_MKL	Uncertain	0.96	D
Vest4		0.88
GERP RS		3.6

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.050		Details are displayed if max score is > 0.2

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr3-49459565;