rs778174763

Positions:

• chr12-63802406-G-A

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PVS1_Strong PM2 PP5_Moderate

The ENST00000261234.11(RXYLT1):​c.743+1G>A variant causes a splice donor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000426 in 1,406,972 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 0.0000043 (0 hom.)
• Consequence: RXYLT1 ENST00000261234.11 splice_donor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 9.31

Genes affected

RXYLT1 (HGNC:13530): (ribitol xylosyltransferase 1) This gene encodes a type II transmembrane protein that is thought to have glycosyltransferase function. Mutations in this gene result in cobblestone lissencephaly. Alternative splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq, May 2013]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.23573573 fraction of the gene. No cryptic splice site detected. Exon removal is inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 12-63802406-G-A is Pathogenic according to our data. Variant chr12-63802406-G-A is described in ClinVar as [Likely_pathogenic]. Clinvar id is 578816.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
RXYLT1	NM_014254.3	c.743+1G>A		splice_donor_variant		ENST00000261234.11	NP_055069.1
RXYLT1	NM_001278237.2	c.-38+1G>A		splice_donor_variant			NP_001265166.1
RXYLT1	XM_047428078.1	c.434+1G>A		splice_donor_variant			XP_047284034.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
RXYLT1	ENST00000261234.11	c.743+1G>A		splice_donor_variant		1	NM_014254.3	ENSP00000261234	P1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD3 exomes AF: 0.00000924 AC: 2 AN: 216442 Hom.: 0 AF XY: 0.00000854 AC XY: 1 AN XY: 117062

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

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: 0.0000194

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000426 AC: 6 AN: 1406972 Hom.: 0 Cov.: 31 AF XY: 0.00000432 AC XY: 3 AN XY: 693710

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: 0.0000127

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000369

Gnomad4 OTH exome AF: 0.0000173

GnomAD4 genome Cov.: 31

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Nov 27, 2023

This sequence change affects a donor splice site in intron 4 of the RXYLT1 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in RXYLT1 are known to be pathogenic (PMID: 23217329, 23519211, 31742715). This variant is present in population databases (rs778174763, gnomAD 0.002%). This variant has not been reported in the literature in individuals affected with RXYLT1-related conditions. ClinVar contains an entry for this variant (Variation ID: 578816). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.61	D
BayesDel_noAF	Pathogenic	0.25
CADD	Pathogenic	33
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	0.99
FATHMM_MKL	Uncertain	0.96	D
MutationTaster	Benign	1.0	D;D
GERP RS		4.9

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.99		Position offset: -1

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

Publications

LitVar

Other links and lift over

dbSNP: rs778174763; hg19: chr12-64196186; COSMIC: COSV54170575; COSMIC: COSV54170575;