3-101304266-TC-AG

Variant names:

• chr3-101304266-TC-AG
• NM_016247.4:c.380_381delGAinsCT
• IMPG2 p.Arg127Pro

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PS1

The NM_016247.4(IMPG2):​c.380_381delGAinsCT​(p.Arg127Pro) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. It is difficult to determine the true allele frequency of this variant because it is of type MNV, and the frequency of such variant types in population databases may be underestimated and unreliable. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another nucleotide change resulting in the same amino acid substitution has been previously reported as Likely pathogenic in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R127Q) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: IMPG2 NM_016247.4 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 5.74
• Publications: 0 publications found

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]

IMPG2 Gene-Disease associations (from GenCC):

• IMPG2-related recessive retinopathy

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• retinitis pigmentosa 56

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P
• vitelliform macular dystrophy 5

  Inheritance: Unknown, AD Classification: DEFINITIVE, LIMITED Submitted by: Labcorp Genetics (formerly Invitae), G2P
• adult-onset foveomacular vitelliform dystrophy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• retinitis pigmentosa

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 4 ACMG points.

• PS1: Transcript NM_016247.4 (IMPG2) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_016247.4. 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
	IMPG2	NM_016247.4	MANE Select	c.380_381delGAinsCT	p.Arg127Pro	missense	N/A	NP_057331.2	Q9BZV3

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	IMPG2	ENST00000193391.8	TSL:1 MANE Select	c.380_381delGAinsCT	p.Arg127Pro	missense	N/A	ENSP00000193391.6	Q9BZV3

Frequencies

GnomAD3 genomes Cov.: 32

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		5.7

Splicing

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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

hg19: chr3-101023110;