chr10-49627681-T-C

Variant names:

• chr10-49627681-T-C
• rs121912823
• NM_020549.5:c.1007T>C

Variant summary

Our verdict is Pathogenic. The variant received 16 ACMG points: 16P and 0B. PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_020549.5(CHAT):​c.1007T>C​(p.Ile336Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,806 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 Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. I336L) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: CHAT NM_020549.5 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:5
• Conservation: PhyloP100: 7.67
• Publications: 12 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: Pathogenic. The variant received 16 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr10-49627680-A-T is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 3383387.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.984
• PP5: Variant 10-49627681-T-C is Pathogenic according to our data. Variant chr10-49627681-T-C is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 17515.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	c.1007T>C	p.Ile336Thr	missense_variant	Exon 7 of 15	ENST00000337653.7	NP_065574.4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CHAT	ENST00000337653.7	c.1007T>C	p.Ile336Thr	missense_variant	Exon 7 of 15	1	NM_020549.5	ENSP00000337103.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251422 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461806 Hom.: 0 Cov.: 32 AF XY: 0.00000413 AC XY: 3 AN XY: 727208

African (AFR) AF: 0.00 AC: 0 AN: 33476

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

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

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

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111950

Other (OTH) AF: 0.0000331 AC: 2 AN: 60386

GnomAD4 genome Cov.: 33

Alfa AF: 0.00 Hom.: 0

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial infantile myasthenia Pathogenic:4

Mar 03, 2016

Neuromuscular Department, Shariati Hospital, Tehran University of Medical Sciences

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

May 01, 2003

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Jun 19, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces isoleucine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 336 of the CHAT protein (p.Ile336Thr). This variant is present in population databases (rs121912823, gnomAD 0.006%). This missense change has been observed in individuals with congenital myasthenic syndrome (PMID: 12609506). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 17515). 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 expected to disrupt CHAT protein function. For these reasons, this variant has been classified as Pathogenic. -

Mar 28, 2024

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Abnormality of the musculature Pathogenic:1

Jul 10, 2021

Kariminejad - Najmabadi Pathology & Genetics Center

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.88
BayesDel_addAF	Pathogenic	0.38	D
BayesDel_noAF	Pathogenic	0.48
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.87	.;.;.;D;.
Eigen	Pathogenic	0.94
Eigen_PC	Pathogenic	0.87
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.95	.;.;D;D;D
M_CAP	Pathogenic	0.39	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.0	.;.;.;H;.
PhyloP100		7.7
PrimateAI	Pathogenic	0.88	D
PROVEAN	Uncertain	-4.3	D;D;D;D;D
REVEL	Pathogenic	0.96
Sift	Uncertain	0.0010	D;D;D;D;D
Sift4G	Uncertain	0.0040	D;D;D;D;D
Polyphen		1.0	.;.;.;D;.
Vest4		0.94
MutPred		0.92		.;.;.;Loss of stability (P = 0.0108);.;
MVP		0.98
MPC		0.95
ClinPred		1.0	D
GERP RS		5.7
Varity_R		0.89
gMVP		0.80
Mutation Taster		=0/100	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.030		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: rs121912823; hg19: chr10-50835727;