rs137854489

Positions:

• chrX-154765465-TTTC-T

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM2 PM4_Supporting PP5_Moderate

The NM_001363.5(DKC1):​c.109_111delCTT​(p.Leu37del) variant causes a conservative inframe deletion change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency: Genomes: not found (cov: 23)
• Consequence: DKC1 NM_001363.5 conservative_inframe_deletion
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:2 O:1
• Conservation: PhyloP100: 7.27

Genes affected

DKC1 (HGNC:2890): (dyskerin pseudouridine synthase 1) This gene functions in two distinct complexes. It plays an active role in telomerase stabilization and maintenance, as well as recognition of snoRNAs containing H/ACA sequences which provides stability during biogenesis and assembly into H/ACA small nucleolar RNA ribonucleoproteins (snoRNPs). This gene is highly conserved and widely expressed, and may play additional roles in nucleo-cytoplasmic shuttling, DNA damage response, and cell adhesion. Mutations have been associated with X-linked dyskeratosis congenita. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jan 2014]

DKC1 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM4: Nonframeshift variant in NON repetitive region in NM_001363.5. Strenght limited to Supporting due to length of the change: 1aa.
• PP5: Variant X-154765465-TTTC-T is Pathogenic according to our data. Variant chrX-154765465-TTTC-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 11583.Status of the report is criteria_provided_single_submitter, 1 stars. Variant chrX-154765465-TTTC-T is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
DKC1	NM_001363.5	c.109_111delCTT	p.Leu37del	conservative_inframe_deletion	3/15	ENST00000369550.10	NP_001354.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
DKC1	ENST00000369550.10	c.109_111delCTT	p.Leu37del	conservative_inframe_deletion	3/15	1	NM_001363.5	ENSP00000358563.5

Frequencies

GnomAD3 genomes Cov.: 23

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 23

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

Dyskeratosis congenita, X-linked Pathogenic:1 Other:1

Pathogenic, no assertion criteria provided	literature only	OMIM	May 01, 1998	- -
not provided, no classification provided	literature only	GeneReviews	-	- -

Dyskeratosis congenita Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

May 15, 2020

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Experimental studies have shown that this in-frame deletion results in compromised telomere maintenance, characterized by shortened telomeres and reduced telomerase activity (PMID: 22058290, 23660516, 21602826, 25992652). This variant has been reported in individuals affected with dyskeratosis congenita (PMID: 9590285, Invitae). ClinVar contains an entry for this variant (Variation ID: 11583). This variant is not present in population databases (ExAC no frequency). This variant, c.109_111delCTT, results in the deletion of 1 amino acid of the DKC1 protein (p.Leu37del), but otherwise preserves the integrity of the reading frame. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs137854489; hg19: chrX-153993740;