chr2-232539990-A-G

Variant names:

• chr2-232539990-A-G
• NM_005199.5:c.56-2A>G

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_005199.5(CHRNG):​c.56-2A>G variant causes a splice acceptor, intron change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: CHRNG NM_005199.5 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 2.96
• Publications: 0 publications found

Genes affected

CHRNG (HGNC:1967): (cholinergic receptor nicotinic gamma subunit) The mammalian muscle-type acetylcholine receptor is a transmembrane pentameric glycoprotein with two alpha subunits, one beta, one delta, and one epsilon (in adult skeletal muscle) or gamma (in fetal and denervated muscle) subunit. This gene, which encodes the gamma subunit, is expressed prior to the thirty-third week of gestation in humans. The gamma subunit of the acetylcholine receptor plays a role in neuromuscular organogenesis and ligand binding and disruption of gamma subunit expression prevents the correct localization of the receptor in cell membranes. Mutations in this gene cause Escobar syndrome and a lethal form of multiple pterygium syndrome. Muscle-type acetylcholine receptor is the major antigen in the autoimmune disease myasthenia gravis.[provided by RefSeq, Sep 2009]

CHRNG Gene-Disease associations (from GenCC):

• autosomal recessive multiple pterygium syndrome

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Ambry Genetics, Orphanet
• CHRNG-associated hypo-akinesia disorder of prenatal onset

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• lethal multiple pterygium syndrome

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Orphanet
• transient neonatal myasthenia gravis

  Inheritance: AR Classification: STRONG Submitted by: Genomics England PanelApp

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 3.1, offset of 8, new splice context is: tgtctattgcgggggcccAGggc. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 2-232539990-A-G is Pathogenic according to our data. Variant chr2-232539990-A-G is described in ClinVar as Pathogenic. ClinVar VariationId is 2506380.Status of the report is criteria_provided_single_submitter, 1 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_005199.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CHRNG	NM_005199.5	MANE Select	c.56-2A>G		splice_acceptor intron	N/A	NP_005190.4

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CHRNG	ENST00000651502.1	MANE Select	c.56-2A>G		splice_acceptor intron	N/A	ENSP00000498757.1	P07510-1
	CHRNG	ENST00000389492.3	TSL:1	c.56-2A>G		splice_acceptor intron	N/A	ENSP00000374143.3	P07510-2
	CHRNG	ENST00000485094.1	TSL:1	n.77-2A>G		splice_acceptor intron	N/A

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions

Significance: Pathogenic

Revision: criteria provided, single submitter

Pathogenic	VUS	Benign	Condition
1	-	-	Autosomal recessive multiple pterygium syndrome (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Benign	-0.37
CADD	Uncertain	25
DANN	Benign	0.88
Eigen	Uncertain	0.62
Eigen_PC	Uncertain	0.34
FATHMM_MKL	Uncertain	0.86	D
PhyloP100		3.0
GERP RS		4.1
PromoterAI		-0.0017	Neutral
Mutation Taster		=12/88	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.75
SpliceAI score (max)		0.44		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.44		Position offset: 2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

hg19: chr2-233404700;