chr17-3648929-GAAGT-G

Position:

• chr17-3648929-GAAGT-G

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PVS1_Moderate PM2 PP3_Moderate PP5_Very_Strong

The NM_004937.3(CTNS):​c.225+5_225+8del variant causes a splice donor, coding sequence change. The variant was absent in control chromosomes in GnomAD project. 1/1 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: CTNS NM_004937.3 splice_donor, coding_sequence
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:2 U:1
• Conservation: PhyloP100: 6.35

Genes affected

CTNS (HGNC:2518): (cystinosin, lysosomal cystine transporter) This gene encodes a seven-transmembrane domain protein that functions to transport cystine out of lysosomes. Its activity is driven by the H+ electrochemical gradient of the lysosomal membrane. Mutations in this gene cause cystinosis, a lysosomal storage disorder. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jul 2009]

LOC105371493 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 14 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.07608695 fraction of the gene. Cryptic splice site detected, with MaxEntScore 4.7, offset of 21, new splice context is: tggGTaggg. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 17-3648929-GAAGT-G is Pathogenic according to our data. Variant chr17-3648929-GAAGT-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 550829.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
CTNS	NM_004937.3	c.225+5_225+8del		splice_donor_variant, coding_sequence_variant	5/12	ENST00000046640.9
LOC105371493	XR_007065579.1	n.1934+1231_1934+1234del		intron_variant, non_coding_transcript_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
CTNS	ENST00000046640.9	c.225+5_225+8del		splice_donor_variant, coding_sequence_variant	5/12	1	NM_004937.3	P1

Frequencies

GnomAD3 genomes Cov.: 32

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

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Nephropathic cystinosis Pathogenic:1 Uncertain:1

Likely pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Mar 18, 2024	- -
Uncertain significance, flagged submission	clinical testing	Counsyl	Feb 24, 2017	- -

Juvenile nephropathic cystinosis;C0950123:Inborn genetic diseases;C2931013:Ocular cystinosis Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 19, 2022

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. This variant disrupts the c.225+5 nucleotide in the CTNS gene. Other variant(s) that disrupt this nucleotide have been determined to be pathogenic (PMID: 11708862). This suggests that this nucleotide is clinically significant, and that variants that disrupt this position are likely to be disease-causing. Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Studies have shown that this variant is associated with altered splicing, but the impact on the resulting protein product is unknown (PMID: 12442267). ClinVar contains an entry for this variant (Variation ID: 550829). This variant is also known as 564+1del4. This variant has been observed in individual(s) with cystinosis (PMID: 12442267). This variant is not present in population databases (gnomAD no frequency). This sequence change falls in intron 5 of the CTNS gene. It does not directly change the encoded amino acid sequence of the CTNS protein. It affects a nucleotide within the consensus splice site. -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.96		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.96		Position offset: 2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1555561048; hg19: chr17-3552223;