chr10-49620583-AG-A

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 18 ACMG points: 18P and 0B. PVS1PM2PP5_Very_Strong

The NM_020549.5(CHAT):c.669delG(p.Gln223HisfsTer10) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,378 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★). Variant results in nonsense mediated mRNA decay.

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

CHAT
NM_020549.5 frameshift

Scores

Not classified

Clinical Significance

Pathogenic criteria provided, multiple submitters, no conflicts P:2

Conservation

PhyloP100: 1.89

Publications

0 publications found

Variant links:

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

CHAT links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 18 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 10-49620583-AG-A is Pathogenic according to our data. Variant chr10-49620583-AG-A is described in ClinVar as Pathogenic. ClinVar VariationId is 461462.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CHAT	NM_020549.5 link	c.669delG	p.Gln223HisfsTer10	frameshift_variant	Exon 4 of 15	ENST00000337653.7	NP_065574.4	P28329-1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CHAT	ENST00000337653.7 link	c.669delG	p.Gln223HisfsTer10	frameshift_variant	Exon 4 of 15	1	NM_020549.5	ENSP00000337103.2		P28329-1

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.84e-7

AC:

AN:

1461378

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

727006

show subpopulations

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

African (AFR)

AF:

0.00

AC:

AN:

33472

American (AMR)

AF:

0.00

AC:

AN:

44708

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26116

East Asian (EAS)

AF:

0.00

AC:

AN:

39650

South Asian (SAS)

AF:

0.00

AC:

AN:

86246

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53394

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5766

European-Non Finnish (NFE)

AF:

9.00e-7

AC:

AN:

1111666

Other (OTH)

AF:

0.00

AC:

AN:

60360

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.325

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

Cov.:

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Familial infantile myasthenia

Pathogenic:2

Mar 23, 2024

Baylor Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Mar 28, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

For these reasons, this variant has been classified as Pathogenic. Loss-of-function variants in CHAT are known to be pathogenic (PMID: 12548525, 21786365, 23292760). This variant has not been reported in the literature in individuals with CHAT-related conditions. ClinVar contains an entry for this variant (Variation ID: 461462). This variant is not present in population databases (ExAC no frequency). This sequence change creates a premature translational stop signal (p.Gln223Hisfs*10) in the CHAT gene. It is expected to result in an absent or disrupted protein product. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

1.9

Mutation Taster

=0/200

disease causing (ClinVar)

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over