2-174799360-G-A

Variant summary

Our verdict is Benign. Variant got -9 ACMG points: 0P and 9B. BP4_Strong BS1_Supporting BS2

The NM_001822.7(CHN1):c.*756C>T variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000108 in 399,478 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: 𝑓 0.000092 (0 hom., cov: 33)
  • Exomes 𝑓: 0.00012 (0 hom.)
• Consequence: CHN1 NM_001822.7 3_prime_UTR
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 0.167

Genes affected

CHN1 (HGNC:1943): (chimerin 1) This gene encodes GTPase-activating protein for ras-related p21-rac and a phorbol ester receptor. It is predominantly expressed in neurons, and plays an important role in neuronal signal-transduction mechanisms. Mutations in this gene are associated with Duane's retraction syndrome 2 (DURS2). Alternatively spliced transcript variants encoding different isoforms have been described for this gene. [provided by RefSeq, Apr 2011]

ACMG classification

Verdict is Benign. Variant got -9 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.88).
• BS1: Variant frequency is greater than expected in population sas. gnomad4 allele frequency = 0.0000923 (14/151710) while in subpopulation SAS AF= 0.000209 (1/4790). AF 95% confidence interval is 0.0000792. There are 0 homozygotes in gnomad4. There are 6 alleles in male gnomad4 subpopulation. Median coverage is 33. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting
• BS2: High AC in GnomAd at 14 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CHN1	NM_001822.7	c.*756C>T		3_prime_UTR_variant	13/13	ENST00000409900.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CHN1	ENST00000409900.9	c.*756C>T		3_prime_UTR_variant	13/13	1	NM_001822.7	P1
CHN1	ENST00000295497.13	c.*756C>T		3_prime_UTR_variant	7/7	1
CHN1	ENST00000652036.1	c.*756C>T		3_prime_UTR_variant	8/8
CHN1	ENST00000443238.6			downstream_gene_variant		4

Frequencies

GnomAD3 genomes AF: 0.0000924 AC: 14 AN: 151596 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000728

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.000209

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.000147

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000114 AC: 7 AN: 61628 Hom.: 0 AF XY: 0.000124 AC XY: 4 AN XY: 32156

Gnomad AFR exome AF: 0.000193

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.000561

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000383

Gnomad OTH exome AF: 0.000488

GnomAD4 exome AF: 0.000117 AC: 29 AN: 247768 Hom.: 0 Cov.: 0 AF XY: 0.000161 AC XY: 22 AN XY: 136384

Gnomad4 AFR exome AF: 0.000152

Gnomad4 AMR exome AF: 0.000166

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000137

Gnomad4 SAS exome AF: 0.000353

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000635

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.0000923 AC: 14 AN: 151710 Hom.: 0 Cov.: 33 AF XY: 0.0000809 AC XY: 6 AN XY: 74152

Gnomad4 AFR AF: 0.0000726

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.000209

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.000147

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000680

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Duane retraction syndrome 2 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 13, 2018

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score, this variant could not be ruled out of causing disease and therefore its association with disease required further investigation. A literature search was performed for the gene, cDNA change, and amino acid change (if applicable). No publications were found based on this search. This variant was therefore classified as a variant of unknown significance for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.88
Cadd	Benign	3.2
Dann	Benign	0.73

Splicing

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

Publications

LitVar

Other links and lift over

dbSNP: rs759449440; hg19: chr2-175664088;