chr17-31232886-G-C

Variant names:

• chr17-31232886-G-C
• rs786202564
• NM_001042492.3:c.3496+5G>C

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM2 PP3_Strong PP5

The NM_001042492.3(NF1):​c.3496+5G>C variant causes a splice region, intron change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 31)
• Consequence: NF1 NM_001042492.3 splice_region, intron
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:2
• Conservation: PhyloP100: 3.91

Genes affected

NF1 (HGNC:7765): (neurofibromin 1) This gene product appears to function as a negative regulator of the ras signal transduction pathway. Mutations in this gene have been linked to neurofibromatosis type 1, juvenile myelomonocytic leukemia and Watson syndrome. The mRNA for this gene is subject to RNA editing (CGA>UGA->Arg1306Term) resulting in premature translation termination. Alternatively spliced transcript variants encoding different isoforms have also been described for this gene. [provided by RefSeq, Jul 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 7 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.
• PP5: Variant 17-31232886-G-C is Pathogenic according to our data. Variant chr17-31232886-G-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 185921.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=2, Pathogenic=1}. Variant chr17-31232886-G-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NF1	NM_001042492.3	c.3496+5G>C		splice_region_variant, intron_variant	Intron 26 of 57	ENST00000358273.9	NP_001035957.1
NF1	NM_000267.3	c.3496+5G>C		splice_region_variant, intron_variant	Intron 26 of 56		NP_000258.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NF1	ENST00000358273.9	c.3496+5G>C		splice_region_variant, intron_variant	Intron 26 of 57	1	NM_001042492.3	ENSP00000351015.4

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 31

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:2

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Neurofibromatosis, type 1 Pathogenic:1 Uncertain:1

Mar 25, 2024

Genomic Medicine Center of Excellence, King Faisal Specialist Hospital and Research Centre

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Nov 24, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change falls in intron 26 of the NF1 gene. It does not directly change the encoded amino acid sequence of the NF1 protein. RNA analysis indicates that this variant induces altered splicing and may result in an absent or altered protein product. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individual(s) with neurofibromatosis type 1 (PMID: 17311297, 18546366; internal data). This variant is also known as being located in intron 20. ClinVar contains an entry for this variant (Variation ID: 185921). Variants that disrupt the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Studies have shown that this variant results in skipping of exon 26, and produces a non-functional protein and/or introduces a premature termination codon (PMID: 18546366; internal data). For these reasons, this variant has been classified as Pathogenic. -

Hereditary cancer-predisposing syndrome Uncertain:1

Aug 19, 2014

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.3496+5G>C intronic variant results from a G to C substitution 5 nucleotides after coding exon 26 in the NF1 gene. This variant was not reported in population based cohorts in the following databases: Database of Single Nucleotide Polymorphisms (dbSNP), NHLBI Exome Sequencing Project (ESP), and 1000 Genomes Project. In the ESP, this variant was not observed in 6503 samples (13006 alleles) with coverage at this position.<span style="background-color: initial;">To date, this alteration has been detected with an allele frequency of approximately 0.01% (greater than 11000 alleles tested) in our clinical cohort. Based on protein sequence alignment, this<span style="background-color: initial;">nucleotide position is highly conserved through mammals. Using two different splice site prediction tools, this alteration is predicted by BDGP to abolish the native donor splice site, and is predicted to weaken (but not abolish) the efficacy of the native donor splice site by ESEfinder; however, direct evidence is unavailable.<span style="background-color: initial;">Since supporting evidence is limited at this time, the clinical significance of c.3496+5G>C remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.46
CADD	Benign	19
DANN	Benign	0.80

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.75		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.75		Position offset: -5

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

Publications

LitVar

Other links and lift over

dbSNP: rs786202564; hg19: chr17-29559904; COSMIC: COSV105255187; COSMIC: COSV105255187;