chr2-232531435-A-C

Variant names:

• chr2-232531435-A-C
• rs561839978
• NM_000751.3:c.904A>C

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM2 PP3_Strong

The NM_000751.3(CHRND):​c.904A>C​(p.Thr302Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000137 in 1,461,760 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: 31)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: CHRND NM_000751.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.41
• Publications: 0 publications found

Genes affected

CHRND (HGNC:1965): (cholinergic receptor nicotinic delta subunit) The acetylcholine receptor of muscle has 5 subunits of 4 different types: 2 alpha and 1 each of beta, gamma and delta subunits. After acetylcholine binding, the receptor undergoes an extensive conformation change that affects all subunits and leads to opening of an ion-conducting channel across the plasma membrane. Defects in this gene are a cause of multiple pterygium syndrome lethal type (MUPSL), congenital myasthenic syndrome slow-channel type (SCCMS), and congenital myasthenic syndrome fast-channel type (FCCMS). Several transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Jul 2015]

CHRND Gene-Disease associations (from GenCC):

• congenital myasthenic syndrome 3A

  Inheritance: AD Classification: STRONG Submitted by: PanelApp Australia, Genomics England PanelApp, Labcorp Genetics (formerly Invitae)
• congenital myasthenic syndrome 3B

  Inheritance: AR Classification: STRONG Submitted by: PanelApp Australia, Genomics England PanelApp
• congenital myasthenic syndrome 3C

  Inheritance: AR Classification: STRONG Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae)
• lethal multiple pterygium syndrome

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae)
• postsynaptic congenital myasthenic syndrome

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.945

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000751.3. 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
	CHRND	NM_000751.3	MANE Select	c.904A>C	p.Thr302Pro	missense	Exon 8 of 12	NP_000742.1
	CHRND	NM_001256657.2		c.859A>C	p.Thr287Pro	missense	Exon 7 of 11	NP_001243586.1
	CHRND	NM_001311196.2		c.601A>C	p.Thr201Pro	missense	Exon 8 of 12	NP_001298125.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CHRND	ENST00000258385.8	TSL:1 MANE Select	c.904A>C	p.Thr302Pro	missense	Exon 8 of 12	ENSP00000258385.3
	CHRND	ENST00000543200.5	TSL:2	c.859A>C	p.Thr287Pro	missense	Exon 7 of 11	ENSP00000438380.1
	CHRND	ENST00000412233.5	TSL:4	n.*77A>C		non_coding_transcript_exon	Exon 6 of 7	ENSP00000398143.1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461760 Hom.: 0 Cov.: 32 AF XY: 0.00000275 AC XY: 2 AN XY: 727186

African (AFR) AF: 0.00 AC: 0 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: 0.0000232 AC: 2 AN: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53324

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

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111982

Other (OTH) AF: 0.00 AC: 0 AN: 60392

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Lethal multiple pterygium syndrome Uncertain:1

Nov 08, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. 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 CHRND protein function. ClinVar contains an entry for this variant (Variation ID: 579854). This variant has not been reported in the literature in individuals affected with CHRND-related conditions. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces threonine, which is neutral and polar, with proline, which is neutral and non-polar, at codon 302 of the CHRND protein (p.Thr302Pro).

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.66
BayesDel_addAF	Pathogenic	0.51	D
BayesDel_noAF	Pathogenic	0.49
CADD	Uncertain	23
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.90	D
Eigen	Pathogenic	0.97
Eigen_PC	Pathogenic	0.87
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Benign	0.82	T
M_CAP	Uncertain	0.13	D
MetaRNN	Pathogenic	0.95	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.1	H
PhyloP100		7.4
PrimateAI	Benign	0.43	T
PROVEAN	Pathogenic	-5.9	D
REVEL	Pathogenic	0.90
Sift	Uncertain	0.0010	D
Sift4G	Uncertain	0.0020	D
Polyphen		0.99	D
Vest4		0.56
MutPred		0.89		Gain of ubiquitination at K297 (P = 0.1688)
MVP		1.0
MPC		1.0
ClinPred		1.0	D
GERP RS		6.1
Varity_R		0.98
gMVP		0.89
Mutation Taster		=33/67	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs561839978; hg19: chr2-233396145;