chr17-29250186-C-A

Position:

• chr17-29250186-C-A

Variant summary

Our verdict is Likely benign. Variant got -2 ACMG points: 2P and 4B. PP3_Moderate BS2

The NM_005208.5(CRYBA1):​c.101C>A​(p.Thr34Asn) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000785 in 1,401,372 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T34I) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000078 (0 hom.)
• Consequence: CRYBA1 NM_005208.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.44

Genes affected

CRYBA1 (HGNC:2394): (crystallin beta A1) 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 acidic group member, encodes two proteins (crystallin, beta A3 and crystallin, beta A1) from a single mRNA, the latter protein is 17 aa shorter than crystallin, beta A3 and is generated by use of an alternate translation initiation site. Deletion of exons 3 and 4 causes the autosomal dominant disease 'zonular cataract with sutural opacities'. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_benign. Variant got -2 ACMG points.

• PP3: MetaRNN computational evidence supports a deleterious effect, 0.906
• BS2: High AC in GnomAdExome4 at 11 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CRYBA1	NM_005208.5	c.101C>A	p.Thr34Asn	missense_variant	3/6	ENST00000225387.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CRYBA1	ENST00000225387.8	c.101C>A	p.Thr34Asn	missense_variant	3/6	1	NM_005208.5	P1
CRYBA1	ENST00000484605.1	c.92C>A	p.Thr31Asn	missense_variant, NMD_transcript_variant	3/5	5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000785 AC: 11 AN: 1401372 Hom.: 0 Cov.: 24 AF XY: 0.0000114 AC XY: 8 AN XY: 700918

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: 0.00000946

Gnomad4 OTH exome AF: 0.0000172

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

EpiCase AF: 0.0000545

EpiControl AF: 0.00

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

Apr 20, 2024

The c.101C>A (p.T34N) alteration is located in exon 3 (coding exon 3) of the CRYBA1 gene. This alteration results from a C to A substitution at nucleotide position 101, causing the threonine (T) at amino acid position 34 to be replaced by an asparagine (N). 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	Uncertain	0.44
BayesDel_addAF	Uncertain	0.11	D
BayesDel_noAF	Benign	-0.090
CADD	Uncertain	24
DANN	Benign	0.93
DEOGEN2	Uncertain	0.78	D
Eigen	Pathogenic	0.93
Eigen_PC	Pathogenic	0.91
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.81	T
M_CAP	Uncertain	0.091	D
MetaRNN	Pathogenic	0.91	D
MetaSVM	Uncertain	0.43	D
MutationAssessor	Pathogenic	3.3	M
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.74	T
PROVEAN	Uncertain	-3.0	D
REVEL	Uncertain	0.53
Sift	Uncertain	0.014	D
Sift4G	Benign	0.24	T
Polyphen		1.0	D
Vest4		0.94
MutPred		0.55		Loss of phosphorylation at T34 (P = 0.1292);
MVP		0.95
MPC		0.83
ClinPred		0.86	D
GERP RS		6.0
Varity_R		0.38
gMVP		0.60

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: rs896498350; hg19: chr17-27577204;