NM_020549.5:c.1198G>C

Variant names:

• chr10-49646591-G-C
• rs8178991
• NM_020549.5:c.1198G>C

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_020549.5(CHAT):​c.1198G>C​(p.Asp400His) variant causes a missense change. The variant allele was found at a frequency of 0.00000186 in 1,614,130 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. D400N) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: CHAT NM_020549.5 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 4.21

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 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CHAT	NM_020549.5	c.1198G>C	p.Asp400His	missense_variant	Exon 8 of 15	ENST00000337653.7	NP_065574.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CHAT	ENST00000337653.7	c.1198G>C	p.Asp400His	missense_variant	Exon 8 of 15	1	NM_020549.5	ENSP00000337103.2

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152252 Hom.: 0 Cov.: 33

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: 0.00000137 AC: 2 AN: 1461878 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 727238

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152252 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74384

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial infantile myasthenia Uncertain:2

Aug 26, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces aspartic acid with histidine at codon 400 of the CHAT protein (p.Asp400His). The aspartic acid residue is moderately conserved and there is a moderate physicochemical difference between aspartic acid and histidine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with CHAT-related conditions. 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) performed at Invitae indicates that this missense variant is not expected to disrupt CHAT protein function. 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. -

Jul 09, 2019

Revvity Omics, Revvity

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.35
BayesDel_addAF	Uncertain	0.076	D
BayesDel_noAF	Benign	-0.13
CADD	Uncertain	25
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.56	.;.;.;D;.;.
Eigen	Uncertain	0.53
Eigen_PC	Uncertain	0.49
FATHMM_MKL	Uncertain	0.92	D
LIST_S2	Uncertain	0.94	.;.;D;D;D;D
M_CAP	Benign	0.075	D
MetaRNN	Uncertain	0.71	D;D;D;D;D;D
MetaSVM	Uncertain	0.17	D
MutationAssessor	Uncertain	2.2	.;.;.;M;.;.
PrimateAI	Uncertain	0.55	T
PROVEAN	Uncertain	-2.8	D;D;D;D;D;.
REVEL	Uncertain	0.54
Sift	Uncertain	0.022	D;D;D;D;D;.
Sift4G	Uncertain	0.033	D;D;D;D;D;.
Polyphen		1.0	.;.;.;D;.;.
Vest4		0.45
MutPred		0.48		.;.;.;Loss of helix (P = 0.028);.;.;
MVP		0.94
MPC		0.79
ClinPred		0.98	D
GERP RS		4.3
Varity_R		0.52
gMVP		0.75

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: rs8178991; hg19: chr10-50854637;