chr22-25224982-A-G

Position:

• chr22-25224982-A-G

Variant summary

Our verdict is Likely benign. Variant got -1 ACMG points: 2P and 3B. PM1 BP4_Moderate BS2_Supporting

The NM_000496.3(CRYBB2):​c.119A>G​(p.Asn40Ser) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000411 in 1,461,384 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/20 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000041 (0 hom.)
• Consequence: CRYBB2 NM_000496.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.35

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]

ACMG classification

Verdict is Likely_benign. Variant got -1 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
• BP4: Computational evidence support a benign effect (MetaRNN=0.2608422).
• BS2: High AC in GnomAdExome4 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	c.119A>G	p.Asn40Ser	missense_variant	3/6	ENST00000398215.3	NP_000487.1
CRYBB2	XM_006724141.4	c.119A>G	p.Asn40Ser	missense_variant	3/6		XP_006724204.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CRYBB2	ENST00000398215.3	c.119A>G	p.Asn40Ser	missense_variant	3/6	1	NM_000496.3	ENSP00000381273	P1
CRYBB2	ENST00000651629.1	c.119A>G	p.Asn40Ser	missense_variant	3/6			ENSP00000498905	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000398 AC: 1 AN: 251474 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135916

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.0000544

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000411 AC: 6 AN: 1461384 Hom.: 0 Cov.: 30 AF XY: 0.00000275 AC XY: 2 AN XY: 727050

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000101

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.00e-7

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Inborn genetic diseases Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 27, 2023

The c.119A>G (p.N40S) alteration is located in exon 3 (coding exon 2) of the CRYBB2 gene. This alteration results from a A to G substitution at nucleotide position 119, causing the asparagine (N) at amino acid position 40 to be replaced by a serine (S). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.076
BayesDel_addAF	Benign	-0.16	T
BayesDel_noAF	Benign	-0.47
CADD	Benign	21
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.42	T
Eigen	Benign	-0.11
Eigen_PC	Benign	0.086
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.87	D
M_CAP	Benign	0.011	T
MetaRNN	Benign	0.26	T
MetaSVM	Benign	-0.77	T
MutationAssessor	Benign	0.54	N
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.49	T
PROVEAN	Uncertain	-2.9	D
REVEL	Benign	0.27
Sift	Benign	0.22	T
Sift4G	Benign	0.27	T
Polyphen		0.019	B
Vest4		0.34
MutPred		0.51		Gain of disorder (P = 0.079);
MVP		0.46
MPC		0.40
ClinPred		0.95	D
GERP RS		5.3
Varity_R		0.35

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: rs749022256; hg19: chr22-25620949;