rs1554807467

Variant names:

• chr10-49648516-G-T
• rs1554807467
• NM_020549.5:c.1291G>T

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_020549.5(CHAT):​c.1291G>T​(p.Gly431Cys) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,466 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 (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: CHAT NM_020549.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.92
• Publications: 0 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 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.886

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.1291G>T	p.Gly431Cys	missense	Exon 9 of 15	NP_065574.4
	CHAT	NM_001142933.2		c.1045G>T	p.Gly349Cys	missense	Exon 10 of 16	NP_001136405.2
	CHAT	NM_001142929.2		c.937G>T	p.Gly313Cys	missense	Exon 9 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.1291G>T	p.Gly431Cys	missense	Exon 9 of 15	ENSP00000337103.2
	CHAT	ENST00000395562.2	TSL:1	c.1045G>T	p.Gly349Cys	missense	Exon 10 of 16	ENSP00000378929.2
	CHAT	ENST00000339797.5	TSL:1	c.937G>T	p.Gly313Cys	missense	Exon 9 of 15	ENSP00000343486.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461466 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727044

African (AFR) AF: 0.00 AC: 0 AN: 33466

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26130

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

South Asian (SAS) AF: 0.00 AC: 0 AN: 86218

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53366

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5748

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111752

Other (OTH) AF: 0.00 AC: 0 AN: 60366

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Familial infantile myasthenia Uncertain:1

Mar 23, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces glycine with cysteine at codon 431 of the CHAT protein (p.Gly431Cys). The glycine residue is moderately conserved and there is a large physicochemical difference between glycine and cysteine. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with a CHAT-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.35
BayesDel_addAF	Pathogenic	0.36	D
BayesDel_noAF	Pathogenic	0.27
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.56	D
Eigen	Uncertain	0.36
Eigen_PC	Uncertain	0.37
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.93	D
M_CAP	Uncertain	0.20	D
MetaRNN	Pathogenic	0.89	D
MetaSVM	Uncertain	-0.023	T
MutationAssessor	Benign	1.8	L
PhyloP100		5.9
PrimateAI	Uncertain	0.76	T
PROVEAN	Uncertain	-3.9	D
REVEL	Pathogenic	0.80
Sift	Uncertain	0.0030	D
Sift4G	Uncertain	0.0040	D
Polyphen		1.0	D
Vest4		0.85
MutPred		0.74		Loss of sheet (P = 0.1158)
MVP		0.92
MPC		0.86
ClinPred		0.99	D
GERP RS		4.1
Varity_R		0.87
gMVP		0.82
Mutation Taster		=18/82	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: rs1554807467; hg19: chr10-50856562;