4-1000990-G-T

Variant names:

• chr4-1000990-G-T
• rs1553916957
• NM_000203.5:c.493+1G>T

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PVS1_Moderate PM2 PP5_Moderate

The NM_000203.5(IDUA):​c.493+1G>T variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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 Pathogenic (★).

• Frequency: Genomes: not found (cov: 34)
• Consequence: IDUA NM_000203.5 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 9.12
• Publications: 0 publications found

Genes affected

IDUA (HGNC:5391): (alpha-L-iduronidase) This gene encodes an enzyme that hydrolyzes the terminal alpha-L-iduronic acid residues of two glycosaminoglycans, dermatan sulfate and heparan sulfate. This hydrolysis is required for the lysosomal degradation of these glycosaminoglycans. Mutations in this gene that result in enzymatic deficiency lead to the autosomal recessive disease mucopolysaccharidosis type I (MPS I). [provided by RefSeq, Jul 2008]

IDUA Gene-Disease associations (from GenCC):

• mucopolysaccharidosis type 1

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen, Myriad Women’s Health
• Scheie syndrome

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, G2P, Labcorp Genetics (formerly Invitae), Orphanet
• Hurler syndrome

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Genomics England PanelApp, PanelApp Australia
• Hurler-Scheie syndrome

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.055045873 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 4-1000990-G-T is Pathogenic according to our data. Variant chr4-1000990-G-T is described in ClinVar as Pathogenic. ClinVar VariationId is 2768867.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
IDUA	NM_000203.5	c.493+1G>T		splice_donor_variant, intron_variant	Intron 4 of 13	ENST00000514224.2	NP_000194.2
IDUA	NM_001363576.1	c.97+1G>T		splice_donor_variant, intron_variant	Intron 3 of 12		NP_001350505.1
IDUA	NR_110313.1	n.581+1G>T		splice_donor_variant, intron_variant	Intron 4 of 13
IDUA	XM_047415650.1	c.493+1G>T		splice_donor_variant, intron_variant	Intron 4 of 11		XP_047271606.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
IDUA	ENST00000514224.2	c.493+1G>T		splice_donor_variant, intron_variant	Intron 4 of 13	2	NM_000203.5	ENSP00000425081.2

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 34

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Mucopolysaccharidosis type 1 Pathogenic:1

Oct 15, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects a donor splice site in intron 4 of the IDUA 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 IDUA are known to be pathogenic (PMID: 11735025, 21480867). This variant is not present in population databases (gnomAD no frequency). Disruption of this splice site has been observed in individual(s) with mucopolysaccharidosis type I (PMID: 21394825). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Uncertain	-0.070
CADD	Pathogenic	31
DANN	Uncertain	0.98
Eigen	Pathogenic	0.89
Eigen_PC	Uncertain	0.64
FATHMM_MKL	Pathogenic	0.99	D
PhyloP100		9.1
GERP RS		4.7
Mutation Taster		=0/100	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.90
SpliceAI score (max)		0.54		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.54		Position offset: -1

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

Other links and lift over

dbSNP: rs1553916957; hg19: chr4-994778;