17-31259080-A-T

Variant names:

• chr17-31259080-A-T
• rs1555618675
• NM_001042492.3:c.4381A>T

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM1 PM2 PM5 PP3 PP5

The NM_001042492.3(NF1):​c.4381A>T​(p.Met1461Leu) variant causes a missense 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. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Uncertain significance in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. M1461V) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: NF1 NM_001042492.3 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:1
• Conservation: PhyloP100: 8.67
• Publications: 0 publications found

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]

NF1 Gene-Disease associations (from GenCC):

• neurofibromatosis type 1

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, PanelApp Australia, G2P, Genomics England PanelApp
• neurofibromatosis-Noonan syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Genomics England PanelApp, PanelApp Australia
• Moyamoya disease

  Inheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
• hereditary pheochromocytoma-paraganglioma

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• familial ovarian cancer

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

• PM1: In a hotspot region, there are 13 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 2 benign, 35 uncertain in NM_001042492.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr17-31259080-A-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 859637.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.762
• PP5: Variant 17-31259080-A-T is Pathogenic according to our data. Variant chr17-31259080-A-T is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 457697.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_001042492.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	NF1	NM_001042492.3	MANE Select	c.4381A>T	p.Met1461Leu	missense	Exon 33 of 58	NP_001035957.1
	NF1	NM_000267.4		c.4318A>T	p.Met1440Leu	missense	Exon 32 of 57	NP_000258.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	NF1	ENST00000358273.9	TSL:1 MANE Select	c.4381A>T	p.Met1461Leu	missense	Exon 33 of 58	ENSP00000351015.4
	NF1	ENST00000356175.7	TSL:1	c.4318A>T	p.Met1440Leu	missense	Exon 32 of 57	ENSP00000348498.3
	NF1	ENST00000579081.6	TSL:1	n.4318A>T		non_coding_transcript_exon	Exon 32 of 58	ENSP00000462408.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Neurofibromatosis, type 1 Pathogenic:2

Jan 05, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces methionine, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 1440 of the NF1 protein (p.Met1440Leu). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with clinical features of neurofibromatosis (Invitae). In at least one individual the variant was observed to be de novo. ClinVar contains an entry for this variant (Variation ID: 457697). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on NF1 protein function. For these reasons, this variant has been classified as Pathogenic.

May 26, 2023

Greenwood Genetic Center Diagnostic Laboratories, Greenwood Genetic Center

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

PM1_Supporting, PM2, PM6, PP2

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

Oct 26, 2023

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.M1440L variant (also known as c.4318A>T), located in coding exon 32 of the NF1 gene, results from an A to T substitution at nucleotide position 4318. The methionine at codon 1440 is replaced by leucine, an amino acid with highly similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, the in silico prediction for this alteration is inconclusive. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.84
BayesDel_addAF	Pathogenic	0.25	D
BayesDel_noAF	Uncertain	0.13
CADD	Uncertain	23
DANN	Benign	0.97
DEOGEN2	Uncertain	0.67	D
Eigen	Uncertain	0.33
Eigen_PC	Uncertain	0.43
FATHMM_MKL	Uncertain	0.96	D
LIST_S2	Uncertain	0.92	D
M_CAP	Pathogenic	0.55	D
MetaRNN	Pathogenic	0.76	D
MetaSVM	Uncertain	0.00060	D
MutationAssessor	Uncertain	2.3	M
PhyloP100		8.7
PrimateAI	Pathogenic	0.87	D
PROVEAN	Benign	-2.3	N
REVEL	Uncertain	0.55
Sift	Benign	0.065	T
Sift4G	Benign	0.11	T
Polyphen		0.048	B
Vest4		0.68
MutPred		0.53		Loss of methylation at K1457 (P = 0.065)
MVP		0.89
MPC		0.64
ClinPred		0.91	D
GERP RS		5.8
Varity_R		0.94
gMVP		0.86
Mutation Taster		=7/93	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs1555618675; hg19: chr17-29586098;