10-49649591-C-T

Variant names:

• chr10-49649591-C-T
• rs764921945
• NM_020549.5:c.1466C>T

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PM1 PP3

The NM_020549.5(CHAT):​c.1466C>T​(p.Pro489Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.0000155 in 1,613,752 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. P489P) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000016 (0 hom.)
• Consequence: CHAT NM_020549.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.57
• Publications: 1 publications found

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]

CHAT Gene-Disease associations (from GenCC):

• congenital myasthenic syndrome 6

  Inheritance: AR Classification: STRONG Submitted by: PanelApp Australia, Labcorp Genetics (formerly Invitae), Genomics England PanelApp
• presynaptic congenital myasthenic syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 9 uncertain in NM_020549.5
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.824

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_020549.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CHAT	NM_020549.5	MANE Select	c.1466C>T	p.Pro489Leu	missense	Exon 10 of 15	NP_065574.4
	CHAT	NM_001142933.2		c.1220C>T	p.Pro407Leu	missense	Exon 11 of 16	NP_001136405.2
	CHAT	NM_001142929.2		c.1112C>T	p.Pro371Leu	missense	Exon 10 of 15	NP_001136401.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CHAT	ENST00000337653.7	TSL:1 MANE Select	c.1466C>T	p.Pro489Leu	missense	Exon 10 of 15	ENSP00000337103.2
	CHAT	ENST00000395562.2	TSL:1	c.1220C>T	p.Pro407Leu	missense	Exon 11 of 16	ENSP00000378929.2
	CHAT	ENST00000339797.5	TSL:1	c.1112C>T	p.Pro371Leu	missense	Exon 10 of 15	ENSP00000343486.1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152194 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000241

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: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.0000320 AC: 8 AN: 249726 AF XY: 0.0000148

Gnomad AFR exome AF: 0.000125

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: 0.0000444

Gnomad OTH exome AF: 0.000164

GnomAD4 exome AF: 0.0000164 AC: 24 AN: 1461558 Hom.: 0 Cov.: 31 AF XY: 0.0000165 AC XY: 12 AN XY: 727070

African (AFR) AF: 0.0000597 AC: 2 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

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

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

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53092

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

European-Non Finnish (NFE) AF: 0.0000180 AC: 20 AN: 1112006

Other (OTH) AF: 0.0000166 AC: 1 AN: 60394

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152194 Hom.: 0 Cov.: 33 AF XY: 0.0000135 AC XY: 1 AN XY: 74336

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.0000241 AC: 1 AN: 41452

American (AMR) AF: 0.00 AC: 0 AN: 15284

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 5190

South Asian (SAS) AF: 0.00 AC: 0 AN: 4822

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10622

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68034

Other (OTH) AF: 0.00 AC: 0 AN: 2092

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.0000282 Hom.: 0

Bravo AF: 0.0000189

ExAC AF: 0.0000330 AC: 4

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Familial infantile myasthenia Uncertain:1

Oct 05, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces proline, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 489 of the CHAT protein (p.Pro489Leu). This variant is present in population databases (rs764921945, gnomAD 0.01%). This variant has not been reported in the literature in individuals affected with CHAT-related conditions. ClinVar contains an entry for this variant (Variation ID: 461448). 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.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.15
BayesDel_addAF	Uncertain	0.066	T
BayesDel_noAF	Uncertain	0.090
CADD	Pathogenic	31
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.80	D
Eigen	Pathogenic	0.74
Eigen_PC	Pathogenic	0.71
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.95	D
M_CAP	Uncertain	0.099	D
MetaRNN	Pathogenic	0.82	D
MetaSVM	Uncertain	0.49	D
MutationAssessor	Pathogenic	3.2	M
PhyloP100		7.6
PrimateAI	Uncertain	0.65	T
PROVEAN	Pathogenic	-7.1	D
REVEL	Pathogenic	0.67
Sift	Uncertain	0.0010	D
Sift4G	Uncertain	0.0070	D
Polyphen		1.0	D
Vest4		0.64
MutPred		0.56		Loss of disorder (P = 0.0526)
MVP		0.96
MPC		0.84
ClinPred		0.99	D
GERP RS		5.0
Varity_R		0.74
gMVP		0.61
Mutation Taster		=19/81	disease causing

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

Other links and lift over

dbSNP: rs764921945; hg19: chr10-50857637; COSMIC: COSV108172266; COSMIC: COSV108172266;