X-71223690-A-T

Variant names:

• chrX-71223690-A-T
• rs751230398
• NM_000166.6:c.-16-2A>T

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1 PM2

The NM_000166.6(GJB1):​c.-16-2A>T variant causes a splice acceptor, intron change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency: Genomes: not found (cov: 22)
• Consequence: GJB1 NM_000166.6 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 6.80
• Publications: 1 publications found

Genes affected

GJB1 (HGNC:4283): (gap junction protein beta 1) This gene encodes a member of the gap junction protein family. The gap junction proteins are membrane-spanning proteins that assemble to form gap junction channels that facilitate the transfer of ions and small molecules between cells. According to sequence similarities at the nucleotide and amino acid levels, the gap junction proteins are divided into two categories, alpha and beta. Mutations in this gene cause X-linked Charcot-Marie-Tooth disease, an inherited peripheral neuropathy. Alternatively spliced transcript variants encoding the same protein have been found for this gene. [provided by RefSeq, Oct 2008]

GJB1 Gene-Disease associations (from GenCC):

• Charcot-Marie-Tooth disease X-linked dominant 1

  Inheritance: XL Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Orphanet, PanelApp Australia, ClinGen, Labcorp Genetics (formerly Invitae)
• X-linked progressive cerebellar ataxia

  Inheritance: XL Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 5.9, offset of -37, new splice context is: cgcccgactttccaccccAGctt. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GJB1	NM_000166.6	c.-16-2A>T		splice_acceptor_variant, intron_variant	Intron 1 of 1	ENST00000361726.7	NP_000157.1
GJB1	NM_001097642.3	c.-16-2A>T		splice_acceptor_variant, intron_variant	Intron 1 of 1		NP_001091111.1
GJB1	NM_001440770.1	c.-16-2A>T		splice_acceptor_variant, intron_variant	Intron 2 of 2		NP_001427699.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GJB1	ENST00000361726.7	c.-16-2A>T		splice_acceptor_variant, intron_variant	Intron 1 of 1	1	NM_000166.6	ENSP00000354900.6

Frequencies

GnomAD3 genomes Cov.: 22

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 22

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.18
CADD	Pathogenic	26
DANN	Uncertain	0.98
PhyloP100		6.8
PromoterAI		0.014	Neutral
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.2

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.95
SpliceAI score (max)		0.98		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.98		Position offset: 2

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

Other links and lift over

dbSNP: rs751230398; hg19: chrX-70443540;