rs121912823

chr10-49627681-T-C

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PM2 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 (★★).

• 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:4
• Conservation: PhyloP100: 7.67

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 Pathogenic. Variant got 14 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• 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 [Likely_pathogenic]. Clinvar id is 17515.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr10-49627681-T-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CHAT	NM_020549.5	c.1007T>C	p.Ile336Thr	missense_variant	7/15	ENST00000337653.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CHAT	ENST00000337653.7	c.1007T>C	p.Ile336Thr	missense_variant	7/15	1	NM_020549.5	P2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251422 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135878

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 SAS exome AF: 0.00

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

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: 8.99e-7

Gnomad4 OTH exome AF: 0.0000331

GnomAD4 genome Cov.: 33

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Familial infantile myasthenia Pathogenic:3

Pathogenic, criteria provided, single submitter	clinical testing	Invitae	Jun 19, 2023	For these reasons, this variant has been classified as Pathogenic. 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. ClinVar contains an entry for this variant (Variation ID: 17515). 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. This variant is present in population databases (rs121912823, gnomAD 0.006%). 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). -
Pathogenic, no assertion criteria provided	clinical testing	Neuromuscular Department, Shariati Hospital, Tehran University of Medical Sciences	Mar 03, 2016	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	May 01, 2003	- -

Abnormality of the musculature Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Kariminejad - Najmabadi Pathology & Genetics Center

Jul 10, 2021

- -

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
Eigen	Pathogenic	0.94
Eigen_PC	Pathogenic	0.87
FATHMM_MKL	Pathogenic	1.0	D
M_CAP	Pathogenic	0.39	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationTaster	Benign	1.0	A;A;A;A;A;A
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

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

Publications

LitVar

Other links and lift over

dbSNP: rs121912823; hg19: chr10-50835727;