11-111908768-T-A

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM2

The NM_001289808.2(CRYAB):c.524A>T(p.Lys175Ile) variant causes a missense change. The variant allele was found at a frequency of 0.00000205 in 1,460,332 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: CRYAB NM_001289808.2 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 4.68

Genes affected

CRYAB (HGNC:2389): (crystallin alpha B) Mammalian lens crystallins are divided into alpha, beta, and gamma families. Alpha crystallins are composed of two gene products: alpha-A and alpha-B, for acidic and basic, respectively. Alpha crystallins can be induced by heat shock and are members of the small heat shock protein (HSP20) family. They act as molecular chaperones although they do not renature proteins and release them in the fashion of a true chaperone; instead they hold them in large soluble aggregates. These heterogeneous aggregates consist of 30-40 subunits; the alpha-A and alpha-B subunits have a 3:1 ratio, respectively. Two additional functions of alpha crystallins are an autokinase activity and participation in the intracellular architecture. The encoded protein has been identified as a moonlighting protein based on its ability to perform mechanistically distinct functions. Alpha-A and alpha-B gene products are differentially expressed; alpha-A is preferentially restricted to the lens and alpha-B is expressed widely in many tissues and organs. Elevated expression of alpha-B crystallin occurs in many neurological diseases; a missense mutation cosegregated in a family with a desmin-related myopathy. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jan 2019]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CRYAB	NM_001289808.2	c.524A>T	p.Lys175Ile	missense_variant	3/3	ENST00000650687.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CRYAB	ENST00000650687.2	c.524A>T	p.Lys175Ile	missense_variant	3/3		NM_001289808.2	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1460332 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 726488

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000270

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000936 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Dilated cardiomyopathy 1II Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Aug 31, 2021

This sequence change replaces lysine with isoleucine at codon 175 of the CRYAB protein (p.Lys175Ile). The lysine residue is moderately conserved and there is a moderate physicochemical difference between lysine and isoleucine. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals affected with CRYAB-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). 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	0.63
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Uncertain	0.080
Cadd	Pathogenic	27
Dann	Uncertain	0.99
DEOGEN2	Benign	0.37	T;T;T;T;T;T;T;T;T
Eigen	Benign	0.11
Eigen_PC	Uncertain	0.24
FATHMM_MKL	Pathogenic	0.99	D
M_CAP	Uncertain	0.23	D
MetaRNN	Uncertain	0.47	T;T;T;T;T;T;T;T;D
MetaSVM	Uncertain	0.58	D
MutationAssessor	Uncertain	2.2	M;.;.;M;M;M;M;M;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D
PrimateAI	Uncertain	0.67	T
PROVEAN	Benign	-2.2	N;D;D;.;N;N;N;N;D
REVEL	Uncertain	0.63
Sift	Uncertain	0.0010	D;D;D;.;D;D;D;D;D
Sift4G	Uncertain	0.0040	D;D;D;D;D;D;D;D;.
Polyphen		0.13	B;.;.;B;B;B;B;B;.
Vest4		0.60
MutPred		0.34		Gain of stability (P = 0.0023);.;.;Gain of stability (P = 0.0023);Gain of stability (P = 0.0023);Gain of stability (P = 0.0023);Gain of stability (P = 0.0023);Gain of stability (P = 0.0023);.;
MVP		0.78
MPC		1.0
ClinPred		0.98	D
GERP RS		4.8
Varity_R		0.76
gMVP		0.45

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: rs1965351856; hg19: chr11-111779492;