22-25221453-G-T

Variant names:

• chr22-25221453-G-T
• rs1935318753
• NM_000496.3:c.24G>T

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 5P and 2B. PM1 PM2 PP2 BP4_Moderate

The NM_000496.3(CRYBB2):​c.24G>T​(p.Gln8His) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000205 in 1,461,706 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 16/21 in silico tools predict a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another nucleotide change resulting in the same amino acid substitution has been previously reported as Uncertain significance in ClinVar.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: CRYBB2 NM_000496.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.850
• Publications: 0 publications found

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 Gene-Disease associations (from GenCC):

• cataract 3 multiple types

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Laboratory for Molecular Medicine, Labcorp Genetics (formerly Invitae), Ambry Genetics
• cataract - microcornea syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• cerulean cataract

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• early-onset nuclear cataract

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• early-onset posterior subcapsular cataract

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• early-onset sutural cataract

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• pulverulent cataract

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• total early-onset cataract

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 ACMG points.

• PM1: In a chain Beta-crystallin B2 (size 203) in uniprot entity CRBB2_HUMAN there are 13 pathogenic changes around while only 4 benign (76%) in NM_000496.3
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 13 curated pathogenic missense variants (we use a threshold of 10). The gene has 2 curated benign missense variants. Gene score misZ: 1.0723 (below the threshold of 3.09). Trascript score misZ: 1.7369 (below the threshold of 3.09). GenCC associations: The gene is linked to cataract 3 multiple types, pulverulent cataract, cataract - microcornea syndrome, early-onset posterior subcapsular cataract, total early-onset cataract, early-onset nuclear cataract, cerulean cataract, early-onset sutural cataract.
• BP4: Computational evidence support a benign effect (MetaRNN=0.18778509).

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000496.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CRYBB2	NM_000496.3	MANE Select	c.24G>T	p.Gln8His	missense	Exon 2 of 6	NP_000487.1	P43320

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CRYBB2	ENST00000398215.3	TSL:1 MANE Select	c.24G>T	p.Gln8His	missense	Exon 2 of 6	ENSP00000381273.2	P43320
	CRYBB2	ENST00000651629.1		c.24G>T	p.Gln8His	missense	Exon 2 of 6	ENSP00000498905.1	P43320
	CRYBB2	ENST00000855619.1		c.24G>T	p.Gln8His	missense	Exon 1 of 5	ENSP00000525678.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 0.00000205 AC: 3 AN: 1461706 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 727156

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44718

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

East Asian (EAS) AF: 0.00 AC: 0 AN: 39692

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53402

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000270 AC: 3 AN: 1111866

Other (OTH) AF: 0.00 AC: 0 AN: 60392

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.097
BayesDel_addAF	Benign	-0.014	T
BayesDel_noAF	Benign	-0.26
CADD	Benign	20
DANN	Uncertain	0.99
DEOGEN2	Benign	0.12	T
Eigen	Benign	-0.10
Eigen_PC	Benign	-0.055
FATHMM_MKL	Benign	0.60	D
LIST_S2	Benign	0.80	T
M_CAP	Benign	0.021	T
MetaRNN	Benign	0.19	T
MetaSVM	Benign	-0.73	T
MutationAssessor	Benign	0.69	N
PhyloP100		0.85
PrimateAI	Benign	0.45	T
PROVEAN	Benign	-1.2	N
REVEL	Benign	0.23
Sift	Benign	0.076	T
Sift4G	Benign	0.12	T
Polyphen		0.80	P
Vest4		0.31
MutPred		0.15		Gain of glycosylation at T7 (P = 0.107)
MVP		0.68
MPC		0.59
ClinPred		0.86	D
GERP RS		1.2
Varity_R		0.093
Mutation Taster		=88/12	polymorphism

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

Other links and lift over

dbSNP: rs1935318753; hg19: chr22-25617420;