22-25221455-C-T

Position:

chr22-25221455-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM1BS1_SupportingBS2_Supporting

The NM_000496.3(CRYBB2):c.26C>T(p.Ala9Val) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000353 in 1,613,728 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

Frequency

Genomes: 𝑓 0.000039 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000035 ( 0 hom. )

Consequence

CRYBB2
NM_000496.3 missense

Scores

Clinical Significance

Uncertain significance criteria provided, multiple submitters, no conflicts U:2

Conservation

PhyloP100: 0.878

Variant links:

Genes affected

CRYBB2 (HGNC:2398): (crystallin beta B2) 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. Beta-crystallins, the most heterogeneous, differ by the presence of the C-terminal extension (present in the basic group, none in the acidic group). Beta-crystallins form aggregates of different sizes and are able to self-associate to form dimers or to form heterodimers with other beta-crystallins. This gene, a beta basic group member, is part of a gene cluster with beta-A4, beta-B1, and beta-B3. A chain-terminating mutation was found to cause type 2 cerulean cataracts. [provided by RefSeq, Jul 2008]

CRYBB2 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Uncertain_significance. Variant got 0 ACMG points.

PM1

In a chain Beta-crystallin B2 (size 203) in uniprot entity CRBB2_HUMAN there are 23 pathogenic changes around while only 1 benign (96%) in NM_000496.3

BS1

Variant frequency is greater than expected in population eas. gnomad4_exome allele frequency = 0.0000349 (51/1461398) while in subpopulation EAS AF= 0.000479 (19/39690). AF 95% confidence interval is 0.000313. There are 0 homozygotes in gnomad4_exome. There are 23 alleles in male gnomad4_exome subpopulation. Median coverage is 30. This position pass quality control queck. Existence of Clinvar submissions makes me limit the strength of this signal to Supporting

BS2

High AC in GnomAd4 at 6 AD gene. Variant has AC lower than other variant known as pathogenic in the gene, so the strength is limited to Supporting.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CRYBB2	NM_000496.3 linkuse as main transcript	c.26C>T	p.Ala9Val	missense_variant	2/6	ENST00000398215.3	NP_000487.1
CRYBB2	XM_006724141.4 linkuse as main transcript	c.26C>T	p.Ala9Val	missense_variant	2/6		XP_006724204.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CRYBB2	ENST00000398215.3 linkuse as main transcript	c.26C>T	p.Ala9Val	missense_variant	2/6	1	NM_000496.3	ENSP00000381273	P1
CRYBB2	ENST00000651629.1 linkuse as main transcript	c.26C>T	p.Ala9Val	missense_variant	2/6			ENSP00000498905	P1

Frequencies

GnomAD3 genomes

AF:

0.0000263

AC:

AN:

152214

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000241

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000131

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.000193

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.0000757

AC:

AN:

250918

Hom.:

AF XY:

0.0000663

AC XY:

AN XY:

135740

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.00

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.000925

Gnomad SAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000176

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000349

AC:

AN:

1461398

Hom.:

Cov.:

AF XY:

0.0000316

AC XY:

AN XY:

727010

show subpopulations

Gnomad4 AFR exome

AF:

0.0000597

Gnomad4 AMR exome

AF:

0.00

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.000479

Gnomad4 SAS exome

AF:

0.0000232

Gnomad4 FIN exome

AF:

0.0000187

Gnomad4 NFE exome

AF:

0.0000216

Gnomad4 OTH exome

AF:

0.0000497

GnomAD4 genome

AF:

0.0000394

AC:

AN:

152330

Hom.:

Cov.:

AF XY:

0.0000403

AC XY:

AN XY:

74490

show subpopulations

Gnomad4 AFR

AF:

0.0000241

Gnomad4 AMR

AF:

0.000261

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.000193

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.0000434

Hom.:

Bravo

AF:

0.0000756

ExAC

AF:

0.0000906

AC:

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Inborn genetic diseases

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 17, 2024

The c.26C>T (p.A9V) alteration is located in exon 2 (coding exon 1) of the CRYBB2 gene. This alteration results from a C to T substitution at nucleotide position 26, causing the alanine (A) at amino acid position 9 to be replaced by a valine (V). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

not provided

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

May 05, 2017

The c.26 C>T variant in the CRYBB2 gene has not been reported previously as a pathogenic variant, nor as a benign variant, to our knowledge. The c.26 C>T variant is not observed at a significant frequency in large population cohorts (Lek et al., 2016; 1000 Genomes Consortium et al., 2015; Exome Variant Server). In-silico splice prediction models predict that c.26 C>T may create a cryptic splice donor site in exon 2. However, in the absence of RNA/functional studies, the actual effect of the c.26 C>T change in this individual is unknown. If c.26 C>T does not alter splicing, it will result in the A9V missense change. The A9V variant is a conservative amino acid substitution, which is not likely to impact secondary protein structure as these residues share similar properties. This substitution occurs at a position that is not conserved. In silico analysis is inconsistent in its predictions as to whether or not the variant is damaging to the protein structure/function. We interpret c.26 C>T as a variant of uncertain significance -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.083

BayesDel_addAF

Benign

-0.33

BayesDel_noAF

Benign

-0.32

CADD

Benign

DANN

Uncertain

1.0

DEOGEN2

Benign

0.10

Eigen

Benign

-0.38

Eigen_PC

Benign

-0.24

FATHMM_MKL

Benign

0.72

LIST_S2

Benign

0.66

M_CAP

Benign

0.026

MetaRNN

Benign

0.031

MetaSVM

Benign

-0.83

MutationAssessor

Uncertain

2.1

MutationTaster

Benign

1.0

PrimateAI

Benign

0.43

PROVEAN

Benign

-1.3

REVEL

Benign

0.18

Sift

Benign

0.046

Sift4G

Uncertain

0.031

Polyphen

0.015

Vest4

0.15

MutPred

0.19

Gain of helix (P = 0.0893);

MVP

0.60

MPC

0.45

ClinPred

0.15

GERP RS

1.4

Varity_R

0.074

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.44

Details are displayed if max score is > 0.2

DS_DG_spliceai

0.44

Position offset: -2

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over