chr2-232539807-G-A

Variant names:

• chr2-232539807-G-A
• NM_005199.5:c.55+5G>A

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM2 PP3_Moderate PP5_Moderate

The NM_005199.5(CHRNG):​c.55+5G>A variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,442 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign 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)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: CHRNG NM_005199.5 splice_region, intron
• Scores: Splicing: ADA: 0.9998
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 1.47
• 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: Ambry Genetics, G2P, 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: Orphanet, PanelApp Australia, Labcorp Genetics (formerly Invitae)
• transient neonatal myasthenia gravis

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

ACMG classification

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

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing predictors support a deleterious effect. Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.
• PP5: Variant 2-232539807-G-A is Pathogenic according to our data. Variant chr2-232539807-G-A is described in ClinVar as Pathogenic. ClinVar VariationId is 2506381.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.55+5G>A		splice_region 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.55+5G>A		splice_region intron	N/A	ENSP00000498757.1	P07510-1
	CHRNG	ENST00000389492.3	TSL:1	c.55+5G>A		splice_region intron	N/A	ENSP00000374143.3	P07510-2
	CHRNG	ENST00000485094.1	TSL:1	n.76+5G>A		splice_region intron	N/A

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461442 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 727028

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

African (AFR) AF: 0.0000299 AC: 1 AN: 33466

American (AMR) AF: 0.00 AC: 0 AN: 44718

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26126

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

South Asian (SAS) AF: 0.00 AC: 0 AN: 86236

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53338

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5518

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

Other (OTH) AF: 0.00 AC: 0 AN: 60358

⚠️ 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.

GnomAD4 genome Cov.: 33

ClinVar

ClinVar submissions as Germline

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_noAF	Benign	-0.78
CADD	Benign	21
DANN	Benign	0.78
PhyloP100		1.5
PromoterAI		0.026	Neutral

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.20		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.20		Position offset: -5

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

Other links and lift over

hg19: chr2-233404517;