NM_020549.5:c.920C>G

Variant names:

• chr10-49625640-C-G
• rs748250869
• NM_020549.5:c.920C>G

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_020549.5(CHAT):​c.920C>G​(p.Ala307Gly) variant causes a missense change. 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 Uncertain significance (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: CHAT NM_020549.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 6.15

Genes affected

CHAT (HGNC:1912): (choline O-acetyltransferase) This gene encodes an enzyme which catalyzes the biosynthesis of the neurotransmitter acetylcholine. This gene product is a characteristic feature of cholinergic neurons, and changes in these neurons may explain some of the symptoms of Alzheimer's disease. Polymorphisms in this gene have been associated with Alzheimer's disease and mild cognitive impairment. Mutations in this gene are associated with congenital myasthenic syndrome associated with episodic apnea. Multiple transcript variants encoding different isoforms have been found for this gene, and some of these variants have been shown to encode more than one isoform. [provided by RefSeq, May 2010]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.762

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CHAT	NM_020549.5	c.920C>G	p.Ala307Gly	missense_variant	Exon 6 of 15	ENST00000337653.7	NP_065574.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CHAT	ENST00000337653.7	c.920C>G	p.Ala307Gly	missense_variant	Exon 6 of 15	1	NM_020549.5	ENSP00000337103.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Familial infantile myasthenia Uncertain:1

Oct 18, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant has not been reported in the literature in individuals affected with CHAT-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces alanine, which is neutral and non-polar, with glycine, which is neutral and non-polar, at codon 307 of the CHAT protein (p.Ala307Gly). ClinVar contains an entry for this variant (Variation ID: 572595). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on CHAT protein function. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.45
BayesDel_addAF	Pathogenic	0.29	D
BayesDel_noAF	Pathogenic	0.18
CADD	Uncertain	24
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.71	.;.;.;D;.
Eigen	Uncertain	0.64
Eigen_PC	Uncertain	0.57
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.96	.;.;D;D;D
M_CAP	Uncertain	0.13	D
MetaRNN	Pathogenic	0.76	D;D;D;D;D
MetaSVM	Pathogenic	0.83	D
MutationAssessor	Pathogenic	3.2	.;.;.;M;.
PrimateAI	Uncertain	0.67	T
PROVEAN	Uncertain	-3.3	D;D;D;D;D
REVEL	Pathogenic	0.78
Sift	Uncertain	0.0030	D;D;D;D;D
Sift4G	Uncertain	0.0030	D;D;D;D;D
Polyphen		0.98	.;.;.;D;.
Vest4		0.64
MutPred		0.59		.;.;.;Loss of sheet (P = 0.1501);.;
MVP		0.94
MPC		0.83
ClinPred		0.99	D
GERP RS		5.3
Varity_R		0.95
gMVP		0.70

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: rs748250869; hg19: chr10-50833686;