rs794727701

Positions:

• chr4-1001467-G-A
• chr4-1001467-G-C

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1_Moderate PM2 PP5_Very_Strong

The NM_000203.5(IDUA):​c.494-1G>A variant causes a splice acceptor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000685 in 1,460,524 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 2/2 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: IDUA NM_000203.5 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 7.73

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 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.04841998 fraction of the gene. Cryptic splice site detected, with MaxEntScore 2, offset of 4, new splice context is: caaggctcctctgcaagtAGgta. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 4-1001467-G-A is Pathogenic according to our data. Variant chr4-1001467-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 557942.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr4-1001467-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
IDUA	NM_000203.5	c.494-1G>A		splice_acceptor_variant, intron_variant		ENST00000514224.2	NP_000194.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
IDUA	ENST00000514224.2	c.494-1G>A		splice_acceptor_variant, intron_variant		2	NM_000203.5	ENSP00000425081.2

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.00000399 AC: 1 AN: 250814 Hom.: 0 AF XY: 0.00000736 AC XY: 1 AN XY: 135798

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: 0.00000883

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1460524 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 726606

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: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Mucopolysaccharidosis type 1 Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Oct 10, 2024

Variant summary: IDUA c.494-1G>A is located in a canonical splice-site and is predicted to affect mRNA splicing resulting in a significantly altered protein due to either exon skipping, shortening, or inclusion of intronic material. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing and loss of IDUA function. Several computational tools predict a significant impact on normal splicing: Four predict the variant weakens a canonical 5' donor site. The variant allele was found at a frequency of 4e-06 in 250814 control chromosomes. c.494-1G>A has been reported in the literature in multiple individuals affected with Mucopolysaccharidosis Type 1/Hurler syndrome (example: Atceken_2016). These data indicate that the variant is very likely to be associated with disease. The following publication has been ascertained in the context of this evaluation (PMID: 27511503). ClinVar contains an entry for this variant (Variation ID: 557942). Based on the evidence outlined above, the variant was classified as pathogenic. -

Hurler syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Counsyl

Apr 20, 2018

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Uncertain	-0.020
CADD	Pathogenic	28
DANN	Uncertain	0.99
Eigen	Pathogenic	0.90
Eigen_PC	Uncertain	0.65
FATHMM_MKL	Pathogenic	0.97	D
GERP RS		4.6
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.1

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
SpliceAI score (max)		0.69		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.69		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: rs794727701; hg19: chr4-995255;