X-73823081-T-G

Position:

• chrX-73823081-T-G

Variant summary

Our verdict is Benign. Variant got -9 ACMG points: 0P and 9B. BP4_Strong BP6 BS2

The ENST00000429829.6(XIST):​n.16820A>C 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 0.00135 in 551,801 control chromosomes in the GnomAD database, including 4 homozygotes. There are 192 hemizygotes in GnomAD. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Benign (no stars).

• Frequency:
  • Genomes: 𝑓 0.0045 (2 hom., 136 hem., cov: 23)
  • Exomes 𝑓: 0.00055 (2 hom. 56 hem.)
• Consequence: XIST ENST00000429829.6 non_coding_transcript_exon
• Clinical Significance: Benign no assertion criteria provided B:1
• Conservation: PhyloP100: 1.07

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 Benign. Variant got -9 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.8).
• BP6: Variant X-73823081-T-G is Benign according to our data. Variant chrX-73823081-T-G is described in ClinVar as [Benign]. Clinvar id is 3045578.Status of the report is no_assertion_criteria_provided, 0 stars.
• BS2: High Homozygotes in GnomAd4 at 2 XL gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
XIST	NR_001564.3	n.16811A>C		non_coding_transcript_exon_variant	6/6
TSIX	NR_003255.2	n.30877T>G		non_coding_transcript_exon_variant	1/1
XIST	NR_191000.1	n.16602A>C		non_coding_transcript_exon_variant	5/5

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
XIST	ENST00000429829.6	n.16820A>C		non_coding_transcript_exon_variant	6/6	1
TSIX	ENST00000604411.1	n.30877T>G		non_coding_transcript_exon_variant	1/1	6
XIST	ENST00000648970.1	n.6784A>C		non_coding_transcript_exon_variant	7/7

Frequencies

GnomAD3 genomes AF: 0.00449 AC: 502 AN: 111902 Hom.: 2 Cov.: 23 AF XY: 0.00402 AC XY: 137 AN XY: 34060

Gnomad AFR AF: 0.0158

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000570

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000564

Gnomad OTH AF: 0.00334

GnomAD3 exomes AF: 0.00115 AC: 182 AN: 158628 Hom.: 2 AF XY: 0.000767 AC XY: 44 AN XY: 57378

Gnomad AFR exome AF: 0.0162

Gnomad AMR exome AF: 0.000155

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

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: 0.000550 AC: 242 AN: 439853 Hom.: 2 Cov.: 0 AF XY: 0.000343 AC XY: 56 AN XY: 163207

Gnomad4 AFR exome AF: 0.0154

Gnomad4 AMR exome AF: 0.000299

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: 0.0000118

Gnomad4 OTH exome AF: 0.000774

GnomAD4 genome AF: 0.00448 AC: 502 AN: 111948 Hom.: 2 Cov.: 23 AF XY: 0.00399 AC XY: 136 AN XY: 34116

Gnomad4 AFR AF: 0.0158

Gnomad4 AMR AF: 0.000569

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000564

Gnomad4 OTH AF: 0.00330

Alfa AF: 0.000653 Hom.: 3

Bravo AF: 0.00437

ClinVar

Significance: Benign

Submissions summary: Benign:1

Revision: no assertion criteria provided

Submissions by phenotype

XIST-related disorder Benign:1

Benign, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

Nov 06, 2019

This variant is classified as 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	-0.80
CADD	Benign	6.1
DANN	Benign	0.75

Splicing

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

Publications

LitVar

Other links and lift over

dbSNP: rs5982487; hg19: chrX-73042916;