rs118203966

chr20-33851064-G-Achr20-33851064-G-C

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PM5 PP3 PP5

The NM_176812.5(CHMP4B):c.481G>A(p.Glu161Lys) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 13/23 in silico tools predict a damaging outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. E161Q) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 33)
• Consequence: CHMP4B NM_176812.5 missense, splice_region
• Scores: Splicing: ADA: 0.9715
• Clinical Significance: Pathogenic no assertion criteria provided P:1
• Conservation: PhyloP100: 10.0

Genes affected

CHMP4B (HGNC:16171): (charged multivesicular body protein 4B) This gene encodes a member of the chromatin-modifying protein/charged multivesicular body protein (CHMP) protein family. The protein is part of the endosomal sorting complex required for transport (ESCRT) complex III (ESCRT-III), which functions in the sorting of endocytosed cell-surface receptors into multivesicular endosomes. The ESCRT machinery also functions in the final abscisson stage of cytokinesis and in the budding of enveloped viruses such as HIV-1. The three proteins of the CHMP4 subfamily interact with programmed cell death 6 interacting protein (PDCD6IP, also known as ALIX), which also functions in the ESCRT pathway. The CHMP4 proteins assemble into membrane-attached 5-nm filaments that form circular scaffolds and promote or stabilize outward budding. These polymers are proposed to help generate the luminal vesicles of multivesicular bodies. Mutations in this gene result in autosomal dominant posterior polar cataracts.[provided by RefSeq, Oct 2009]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a chain Charged multivesicular body protein 4b (size 222) in uniprot entity CHM4B_HUMAN there are 6 pathogenic changes around while only 0 benign (100%) in NM_176812.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr20-33851064-G-C is described in Lovd as [Likely_pathogenic].
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.
• PP5: Variant 20-33851064-G-A is Pathogenic according to our data. Variant chr20-33851064-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 1086.Status of the report is no_assertion_criteria_provided, 0 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CHMP4B	NM_176812.5	c.481G>A	p.Glu161Lys	missense_variant, splice_region_variant	3/5	ENST00000217402.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CHMP4B	ENST00000217402.3	c.481G>A	p.Glu161Lys	missense_variant, splice_region_variant	3/5	1	NM_176812.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 25

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: no assertion criteria provided

Submissions by phenotype

Cataract 31 multiple types Pathogenic:1

Pathogenic, no assertion criteria provided

literature only

OMIM

Sep 01, 2007

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Pathogenic	0.44	D
BayesDel_noAF	Pathogenic	0.39
Cadd	Pathogenic	35
Dann	Pathogenic	1.0
DEOGEN2	Pathogenic	0.91	D
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	1.0	D
LIST_S2	Uncertain	0.91	D
M_CAP	Uncertain	0.19	D
MetaRNN	Pathogenic	0.98	D
MetaSVM	Pathogenic	0.88	D
MutationAssessor	Pathogenic	3.9	H
MutationTaster	Benign	1.0	A
PrimateAI	Pathogenic	0.91	D
PROVEAN	Uncertain	-3.6	D
REVEL	Pathogenic	0.82
Sift	Uncertain	0.0080	D
Sift4G	Uncertain	0.0020	D
Polyphen		1.0	D
Vest4		0.93
MutPred		0.90		Gain of ubiquitination at E161 (P = 0.0018);
MVP		0.98
MPC		2.5
ClinPred		1.0	D
GERP RS		6.0
Varity_R		0.95
gMVP		0.83

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	0.97
dbscSNV1_RF	Pathogenic	0.84
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: rs118203966; hg19: chr20-32438870; COSMIC: COSV54135303;