3-101223866-C-A

Variant summary

Our verdict is Likely benign. Variant got -5 ACMG points: 0P and 5B. BP4_Strong BS1_Supporting

The NM_016247.4(IMPG2):c.*3103G>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 0.000223 in 152,288 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 0.00022 (0 hom., cov: 33)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: IMPG2 NM_016247.4 3_prime_UTR
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: -1.91

Genes affected

IMPG2 (HGNC:18362): (interphotoreceptor matrix proteoglycan 2) The protein encoded by this gene binds chondroitin sulfate and hyaluronan and is a proteoglycan. The encoded protein plays a role in the organization of the interphotoreceptor matrix and may promote the growth and maintenance of the light-sensitive photoreceptor outer segment. Defects in this gene are a cause of retinitis pigmentosa type 56 and maculopathy, IMPG2-related.[provided by RefSeq, Mar 2011]

ACMG classification

Verdict is Likely_benign. Variant got -5 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.95).
• BS1: Variant frequency is greater than expected in population sas. gnomad4 allele frequency = 0.000223 (34/152288) while in subpopulation SAS AF= 0.00124 (6/4830). AF 95% confidence interval is 0.000541. There are 0 homozygotes in gnomad4. There are 22 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

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
IMPG2	NM_016247.4	c.*3103G>T		3_prime_UTR_variant	19/19	ENST00000193391.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
IMPG2	ENST00000193391.8	c.*3103G>T		3_prime_UTR_variant	19/19	1	NM_016247.4	P1

Frequencies

GnomAD3 genomes AF: 0.000223 AC: 34 AN: 152170 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000327

Gnomad ASJ AF: 0.00317

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00124

Gnomad FIN AF: 0.0000943

Gnomad MID AF: 0.00633

Gnomad NFE AF: 0.000103

Gnomad OTH AF: 0.000956

GnomAD4 exome Data not reliable, filtered out with message: AC0;AS_VQSR AF: 0.00 AC: 0 AN: 34 Hom.: 0 Cov.: 0 AF XY: 0.00 AC XY: 0 AN XY: 30

Gnomad4 ASJ exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.000223 AC: 34 AN: 152288 Hom.: 0 Cov.: 33 AF XY: 0.000295 AC XY: 22 AN XY: 74464

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.000327

Gnomad4 ASJ AF: 0.00317

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00124

Gnomad4 FIN AF: 0.0000943

Gnomad4 NFE AF: 0.000103

Gnomad4 OTH AF: 0.000946

Bravo AF: 0.000332

Asia WGS AF: 0.000577 AC: 2 AN: 3478

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Retinitis pigmentosa Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Jan 12, 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	-0.95
Cadd	Benign	0.33
Dann	Benign	0.39

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		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: rs566200595; hg19: chr3-100942710;