X-73822111-G-A

Position:

• chrX-73822111-G-A

Variant summary

Our verdict is Likely benign. Variant got -6 ACMG points: 0P and 6B. BP4_Strong BP6 BS2_Supporting

The ENST00000429829.6(XIST):​n.17790C>T variant causes a non coding transcript exon change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000111 in 557,398 control chromosomes in the GnomAD database, with no homozygous occurrence. There are 23 hemizygotes in GnomAD. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (no stars).

• Frequency:
  • Genomes: 𝑓 0.00013 (0 hom., 5 hem., cov: 23)
  • Exomes 𝑓: 0.00011 (0 hom. 18 hem.)
• Consequence: XIST ENST00000429829.6 non_coding_transcript_exon
• Clinical Significance: Likely benign no assertion criteria provided B:1
• Conservation: PhyloP100: -0.0520

Genes affected

XIST (HGNC:12810): (X inactive specific transcript) X inactivation is an early developmental process in mammalian females that transcriptionally silences one of the pair of X chromosomes, thus providing dosage equivalence between males and females. The process is regulated by several factors, including a region of chromosome X called the X inactivation center (XIC). The XIC comprises several non-coding and protein-coding genes, and this gene was the first non-coding gene identified within the XIC. This gene is expressed exclusively from the XIC of the inactive X chromosome, and is essential for the initiation and spread of X-inactivation. The transcript is a spliced RNA. Alternatively spliced transcript variants have been identified, but their full length sequences have not been determined. Mutations in the XIST promoter cause familial skewed X inactivation. [provided by RefSeq, Apr 2012]

TSIX (HGNC:12377): (TSIX transcript, XIST antisense RNA) In mammals, dosage compensation of genes on the X chromosome occurs by X inactivation, which is regulated in cis by the X-inactivation center (XIC) and expression of the XIST non-coding RNA. This gene expresses a non-coding antisense transcript across the 3' end of the XIST locus, and is coexpressed with XIST only from the inactive X chromosome. The mouse ortholog of this locus is required for imprinted X inactivation in extraembryonic tissues and silences Xist through modification of the chromatin structure in the Xist promoter region. In contrast, imprinted X inactivation does not occur in human extraembryonic tissues and transcripts from this locus do not repress XIST expression or affect random X chromosome inactivation in embryonic cells. This transcript is thought to be unspliced and extend over more than 30 kb, but its exact nature has not been determined. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_benign. Variant got -6 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.85).
• BP6: Variant X-73822111-G-A is Benign according to our data. Variant chrX-73822111-G-A is described in ClinVar as [Likely_benign]. Clinvar id is 3048676.Status of the report is no_assertion_criteria_provided, 0 stars.
• BS2: High Hemizygotes in GnomAd4 at 5 XL geneVariant has number of hemizygotes 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
XIST	NR_001564.3	n.17781C>T		non_coding_transcript_exon_variant	6/6
TSIX	NR_003255.2	n.29907G>A		non_coding_transcript_exon_variant	1/1
XIST	NR_190997.1	n.13883C>T		non_coding_transcript_exon_variant	7/8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
XIST	ENST00000429829.6	n.17790C>T		non_coding_transcript_exon_variant	6/6	1
XIST	ENST00000416330.2	n.491C>T		non_coding_transcript_exon_variant	3/4	2
XIST	ENST00000417942.5	n.310C>T		non_coding_transcript_exon_variant	2/3	3

Frequencies

GnomAD3 genomes AF: 0.000134 AC: 15 AN: 112186 Hom.: 0 Cov.: 23 AF XY: 0.000146 AC XY: 5 AN XY: 34354

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00419

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000413 AC: 68 AN: 164619 Hom.: 0 AF XY: 0.000402 AC XY: 25 AN XY: 62155

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00518

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: 0.000106 AC: 47 AN: 445158 Hom.: 0 Cov.: 0 AF XY: 0.000108 AC XY: 18 AN XY: 167232

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00173

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome AF: 0.000134 AC: 15 AN: 112240 Hom.: 0 Cov.: 23 AF XY: 0.000145 AC XY: 5 AN XY: 34418

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00421

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.000121

ClinVar

Significance: Likely benign

Submissions summary: Benign:1

Revision: no assertion criteria provided

Submissions by phenotype

XIST-related disorder Benign:1

Likely benign, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

Dec 13, 2019

This variant is classified as likely benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.85
CADD	Benign	1.8
DANN	Benign	0.46

Splicing

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

Publications

LitVar

Other links and lift over

dbSNP: rs746371115; hg19: chrX-73041946;