chr22-25221443-A-G

Variant names:

• chr22-25221443-A-G
• rs7291633
• NM_000496.3:c.14A>G

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.14A>G​(p.His5Arg) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency: Genomes: not found (cov: 32)
• Consequence: CRYBB2 NM_000496.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 2.63
• Publications: 1 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: Ambry Genetics, Labcorp Genetics (formerly Invitae), G2P, Laboratory for Molecular Medicine
• 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 12 pathogenic changes around while only 4 benign (75%) 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=0.13982436).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
CRYBB2	NM_000496.3	c.14A>G	p.His5Arg	missense_variant	Exon 2 of 6	ENST00000398215.3	NP_000487.1
CRYBB2	XM_006724141.4	c.14A>G	p.His5Arg	missense_variant	Exon 2 of 6		XP_006724204.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CRYBB2	ENST00000398215.3	c.14A>G	p.His5Arg	missense_variant	Exon 2 of 6	1	NM_000496.3	ENSP00000381273.2
CRYBB2	ENST00000651629.1	c.14A>G	p.His5Arg	missense_variant	Exon 2 of 6			ENSP00000498905.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.00000378

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.096
BayesDel_addAF	Uncertain	0.024	T
BayesDel_noAF	Benign	-0.20
CADD	Benign	19
DANN	Uncertain	0.98
DEOGEN2	Benign	0.078	T
Eigen	Benign	-0.12
Eigen_PC	Benign	0.063
FATHMM_MKL	Uncertain	0.93	D
LIST_S2	Benign	0.60	T
M_CAP	Benign	0.011	T
MetaRNN	Benign	0.14	T
MetaSVM	Benign	-1.0	T
MutationAssessor	Uncertain	2.2	M
PhyloP100		2.6
PrimateAI	Uncertain	0.53	T
PROVEAN	Benign	-1.0	N
REVEL	Benign	0.18
Sift	Benign	0.043	D
Sift4G	Benign	0.33	T
Polyphen		0.090	B
Vest4		0.22
MutPred		0.21		Gain of phosphorylation at T3 (P = 0.0693);
MVP		0.74
MPC		0.56
ClinPred		0.64	D
GERP RS		5.1
Varity_R		0.20
Mutation Taster		=48/52	disease causing

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: rs7291633; hg19: chr22-25617410;