16-17108705-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 3 ACMG points: 3P and 0B. PM2 PP3

The NM_022166.4(XYLT1):c.2870G>A(p.Arg957Gln) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000047 in 1,575,366 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R957W) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.000039 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000048 (0 hom.)
• Consequence: XYLT1 NM_022166.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 7.71

Genes affected

XYLT1 (HGNC:15516): (xylosyltransferase 1) This locus encodes a xylosyltransferase enzyme. The encoded protein catalyzes transfer of UDP-xylose to serine residues of an acceptor protein substrate. This transfer reaction is necessary for biosynthesis of glycosaminoglycan chains. Mutations in this gene have been associated with increased severity of pseudoxanthoma elasticum.[provided by RefSeq, Nov 2009]

ACMG classification

Verdict is Uncertain_significance. Variant got 3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.832

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
XYLT1	NM_022166.4	c.2870G>A	p.Arg957Gln	missense_variant	12/12	ENST00000261381.7
XYLT1	XM_047434458.1	c.2831G>A	p.Arg944Gln	missense_variant	11/11

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
XYLT1	ENST00000261381.7	c.2870G>A	p.Arg957Gln	missense_variant	12/12	1	NM_022166.4	P1

Frequencies

GnomAD3 genomes AF: 0.0000394 AC: 6 AN: 152146 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000965

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

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: 0.0000294

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.0000216 AC: 5 AN: 231564 Hom.: 0 AF XY: 0.0000239 AC XY: 3 AN XY: 125532

Gnomad AFR exome AF: 0.0000630

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.0000358

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000277

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000478 AC: 68 AN: 1423220 Hom.: 0 Cov.: 30 AF XY: 0.0000526 AC XY: 37 AN XY: 703542

Gnomad4 AFR exome AF: 0.0000907

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000102

Gnomad4 SAS exome AF: 0.0000722

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000485

Gnomad4 OTH exome AF: 0.0000339

GnomAD4 genome AF: 0.0000394 AC: 6 AN: 152146 Hom.: 0 Cov.: 32 AF XY: 0.0000404 AC XY: 3 AN XY: 74336

Gnomad4 AFR AF: 0.0000965

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000294

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000529

TwinsUK AF: 0.00 AC: 0

ALSPAC AF: 0.000259 AC: 1

ExAC AF: 0.0000330 AC: 4

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Desbuquois dysplasia 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Oct 25, 2021

This sequence change replaces arginine, which is basic and polar, with glutamine, which is neutral and polar, at codon 957 of the XYLT1 protein (p.Arg957Gln). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This variant has not been reported in the literature in individuals affected with XYLT1-related conditions. Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.39
BayesDel_addAF	Pathogenic	0.22	D
BayesDel_noAF	Uncertain	0.080
Cadd	Pathogenic	32
Dann	Pathogenic	1.0
DEOGEN2	Benign	0.30	T
Eigen	Pathogenic	0.92
Eigen_PC	Pathogenic	0.89
FATHMM_MKL	Uncertain	0.94	D
M_CAP	Benign	0.034	D
MetaRNN	Pathogenic	0.83	D
MetaSVM	Benign	-0.87	T
MutationAssessor	Uncertain	2.6	M
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.63	T
PROVEAN	Uncertain	-3.4	D
REVEL	Uncertain	0.53
Sift	Pathogenic	0.0	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.91
MVP		0.34
MPC		0.89
ClinPred		0.98	D
GERP RS		5.7
Varity_R		0.85
gMVP		0.88

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.040		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: rs765703210; hg19: chr16-17202562;