chr17-31163376-G-C

Variant names:

• chr17-31163376-G-C
• rs199474752
• NM_001042492.3:c.479G>C

Variant summary

Our verdict is Pathogenic. Variant got 17 ACMG points: 17P and 0B. PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_001042492.3(NF1):​c.479G>C​(p.Arg160Thr) variant causes a missense, splice region 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. 11/18 in silico tools predict a damaging outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R160K) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: NF1 NM_001042492.3 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:3 O:1
• Conservation: PhyloP100: 9.18

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 Pathogenic. Variant got 17 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr17-31163376-G-A is described in Lovd as [Pathogenic].
• PP2: Missense variant in the NF1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 399 curated pathogenic missense variants (we use a threshold of 10). The gene has 143 curated benign missense variants. Gene score misZ: 6.5427 (above the threshold of 3.09). Trascript score misZ: 8.4054 (above the threshold of 3.09). GenCC associations: The gene is linked to neurofibromatosis, familial spinal, hereditary pheochromocytoma-paraganglioma, neurofibromatosis type 1, Watson syndrome, neurofibromatosis-Noonan syndrome, Moyamoya disease, familial ovarian cancer.
• 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 17-31163376-G-C is Pathogenic according to our data. Variant chr17-31163376-G-C is described in ClinVar as [Pathogenic]. Clinvar id is 68353.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NF1	NM_001042492.3	c.479G>C	p.Arg160Thr	missense_variant, splice_region_variant	Exon 4 of 58	ENST00000358273.9	NP_001035957.1
NF1	NM_000267.3	c.479G>C	p.Arg160Thr	missense_variant, splice_region_variant	Exon 4 of 57		NP_000258.1
NF1	NM_001128147.3	c.479G>C	p.Arg160Thr	missense_variant, splice_region_variant	Exon 4 of 15		NP_001121619.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NF1	ENST00000358273.9	c.479G>C	p.Arg160Thr	missense_variant, splice_region_variant	Exon 4 of 58	1	NM_001042492.3	ENSP00000351015.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:3 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Neurofibromatosis, type 1 Pathogenic:2

Mar 08, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. This sequence change affects codon 160 of the NF1 mRNA. It is a 'silent' change, meaning that it does not 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 disrupted protein product. This variant is not present in population databases (gnomAD no frequency). This variant has been observed in individual(s) with Neurofibromatosis type I (NF1) (PMID: 17311297, 21838856; Invitae). ClinVar contains an entry for this variant (Variation ID: 68353). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated. 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 4 and introduces a premature termination codon (PMID: 17311297). The resulting mRNA is expected to undergo nonsense-mediated decay. -

Aug 17, 2022

Medical Genetics, University of Parma

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Hereditary cancer-predisposing syndrome;CN230736:Cardiovascular phenotype Pathogenic:1

Sep 18, 2018

Ambry Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The c.479G>C pathogenic mutation (also known as p.R160T), located in coding exon 4 of the NF1 gene, results from a G to C substitution at nucleotide position 479. The amino acid change results in arginine to threonine at codon 160, an amino acid with similar properties. However, this change occurs in the last base pair of coding exon 4, which makes it likely to have some effect on normal mRNA splicing. This variant has been identified in patients meeting NIH diagnostic criteria for Neurofibromatosis type 1 (NF1) (Wimmer K et al. Hum. Mutat. 2007 Jun;28:599-612; Stella A et al. Genes (Basel) 2018 Apr;9(4)216). This mutation has also been reported in a patient with classic features of NF1 whose mother had breast cancer diagnosed at 59 (Ponti G et al. Hered Cancer Clin Pract 2011 Aug;9:6). Additionally, protein truncation testing (PTT) showed this variant results in skipping of exon 4 (Wimmer K et al. Hum. Mutat. 2007 Jun;28:599-612). Based on the available evidence, this variant is classified as a pathogenic mutation. -

not provided Other:1

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UniProtKB/Swiss-Prot

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

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Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.38	D
BayesDel_noAF	Pathogenic	0.31
CADD	Pathogenic	34
DANN	Benign	0.90
Eigen	Pathogenic	0.89
Eigen_PC	Pathogenic	0.89
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.45	T
M_CAP	Pathogenic	0.85	D
MetaRNN	Pathogenic	0.87	D
ClinPred		0.91	D
GERP RS		5.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.8

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	1.0
SpliceAI score (max)		0.92		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.92		Position offset: 0

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

Publications

LitVar

Other links and lift over

dbSNP: rs199474752; hg19: chr17-29490394;