3-186539371-C-T

Position:

• chr3-186539371-C-T

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM1 PM2 PP3_Strong

The NM_017541.4(CRYGS):​c.248G>A​(p.Cys83Tyr) variant causes a missense 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. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: CRYGS NM_017541.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.91

Genes affected

CRYGS (HGNC:2417): (crystallin gamma S) Crystallins are separated into two classes: taxon-specific, or enzyme, and ubiquitous. The latter class constitutes the major proteins of vertebrate eye lens and maintains the transparency and refractive index of the lens. Since lens central fiber cells lose their nuclei during development, these crystallins are made and then retained throughout life, making them extremely stable proteins. Mammalian lens crystallins are divided into alpha, beta, and gamma families; beta and gamma crystallins are also considered as a superfamily. Alpha and beta families are further divided into acidic and basic groups. Seven protein regions exist in crystallins: four homologous motifs, a connecting peptide, and N- and C-terminal extensions. Gamma-crystallins are a homogeneous group of highly symmetrical, monomeric proteins typically lacking connecting peptides and terminal extensions. They are differentially regulated after early development. This gene encodes a protein initially considered to be a beta-crystallin but the encoded protein is monomeric and has greater sequence similarity to other gamma-crystallins. This gene encodes the most significant gamma-crystallin in adult eye lens tissue. Whether due to aging or mutations in specific genes, gamma-crystallins have been involved in cataract formation. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM1: In a chain Gamma-crystallin S (size 176) in uniprot entity CRYGS_HUMAN there are 5 pathogenic changes around while only 2 benign (71%) in NM_017541.4
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.951

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CRYGS	NM_017541.4	c.248G>A	p.Cys83Tyr	missense_variant	2/3	ENST00000307944.6	NP_060011.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CRYGS	ENST00000307944.6	c.248G>A	p.Cys83Tyr	missense_variant	2/3	1	NM_017541.4	ENSP00000312099.5
CRYGS	ENST00000460288.1	n.1150G>A		non_coding_transcript_exon_variant	1/2	1
CRYGS	ENST00000392499.6	c.248G>A	p.Cys83Tyr	missense_variant	3/4	2		ENSP00000376287.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Cataract 20 multiple types Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Mar 21, 2021

This sequence change replaces cysteine with tyrosine at codon 83 of the CRYGS protein (p.Cys83Tyr). The cysteine residue is highly conserved and there is a large physicochemical difference between cysteine and tyrosine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with CRYGS-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.97
BayesDel_addAF	Pathogenic	0.42	D
BayesDel_noAF	Pathogenic	0.36
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.83	D;D
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	1.0
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.90	.;D
M_CAP	Uncertain	0.13	D
MetaRNN	Pathogenic	0.95	D;D
MetaSVM	Uncertain	0.57	D
PrimateAI	Uncertain	0.71	T
PROVEAN	Pathogenic	-10	D;D
REVEL	Pathogenic	0.75
Sift	Pathogenic	0.0	D;D
Sift4G	Uncertain	0.054	T;T
Polyphen		1.0	D;D
Vest4		0.99
MutPred		0.73		Gain of phosphorylation at C83 (P = 0.0542);Gain of phosphorylation at C83 (P = 0.0542);
MVP		0.95
MPC		0.84
ClinPred		0.98	D
GERP RS		6.2
Varity_R		0.98
gMVP		0.84

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: rs1714002434; hg19: chr3-186257160;