rs886039099

chr11-111910327-C-G

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PP3_Strong

The NM_001289808.2(CRYAB):c.324G>C(p.Gln108His) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000558 in 1,614,094 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 2/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000055 (0 hom.)
• Consequence: CRYAB NM_001289808.2 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:2
• Conservation: PhyloP100: 7.67

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 Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 3 uncertain in NM_001289808.2
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF. No scorers claiming Uncertain. Scorers claiming Benign: max_spliceai.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CRYAB	NM_001289808.2	c.324G>C	p.Gln108His	missense_variant, splice_region_variant	2/3	ENST00000650687.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CRYAB	ENST00000650687.2	c.324G>C	p.Gln108His	missense_variant, splice_region_variant	2/3		NM_001289808.2	P1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152214 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000147

Gnomad OTH AF: 0.00

GnomAD4 exome AF: 0.00000547 AC: 8 AN: 1461880 Hom.: 0 Cov.: 32 AF XY: 0.00000550 AC XY: 4 AN XY: 727240

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: 0.00000719

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152214 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74364

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000147

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Dilated cardiomyopathy 1II Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Jan 25, 2024

This sequence change replaces glutamine, which is neutral and polar, with histidine, which is basic and polar, at codon 108 of the CRYAB protein (p.Gln108His). This variant also falls at the last nucleotide of exon 3, which is part of the consensus splice site for this exon. This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with CRYAB-related conditions. ClinVar contains an entry for this variant (Variation ID: 264247). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be disruptive. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). 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. -

Cardiovascular phenotype Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Apr 23, 2020

The p.Q108H variant (also known as c.324G>C), located in coding exon 2 of the CRYAB gene, results from a G to C substitution at nucleotide position 324. This change occurs in the last base pair of coding exon 2, which makes it likely to have some effect on normal mRNA splicing. In addition to potential splicing impact, this alteration changes the glutamine at codon 108 to histidine, an amino acid with highly similar properties. Both the nucleotide and amino acid positions are highly conserved in available vertebrate species. Using the BDGP and ESEfinder splice site prediction tools, this alteration is predicted to weaken the efficiency of the native splice donor site; however, direct experimental evidence is unavailable. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.69
BayesDel_addAF	Pathogenic	0.24	D
BayesDel_noAF	Uncertain	0.11
Cadd	Pathogenic	34
Dann	Uncertain	1.0
DEOGEN2	Pathogenic	0.86	D;T;T;D;D;D;D;D;T;D;.;D;D
Eigen	Pathogenic	0.92
Eigen_PC	Pathogenic	0.90
FATHMM_MKL	Pathogenic	0.99	D
M_CAP	Uncertain	0.16	D
MetaRNN	Pathogenic	0.76	D;D;D;D;D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.90	D
MutationAssessor	Uncertain	2.9	M;.;.;M;M;M;M;M;.;.;.;.;.
MutationTaster	Benign	1.0	D;D;D;D;D;D;D;D
PrimateAI	Uncertain	0.69	T
PROVEAN	Uncertain	-3.7	D;D;D;.;D;D;D;D;D;D;D;D;D
REVEL	Pathogenic	0.69
Sift	Uncertain	0.0030	D;D;D;.;D;D;D;D;D;D;D;D;D
Sift4G	Uncertain	0.0070	D;D;D;D;D;D;D;D;.;.;.;.;D
Polyphen		1.0	D;.;.;D;D;D;D;D;.;.;.;.;D
Vest4		0.61
MutPred		0.45		Loss of stability (P = 0.109);.;.;Loss of stability (P = 0.109);Loss of stability (P = 0.109);Loss of stability (P = 0.109);Loss of stability (P = 0.109);Loss of stability (P = 0.109);.;Loss of stability (P = 0.109);.;Loss of stability (P = 0.109);Loss of stability (P = 0.109);
MVP		0.98
MPC		0.89
ClinPred		1.0	D
GERP RS		6.0
Varity_R		0.94
gMVP		0.62

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.99
SpliceAI score (max)		0.010		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: rs886039099; hg19: chr11-111781051;