17-31226487-C-A

Variant names:

• chr17-31226487-C-A
• rs876658190
• NM_001042492.3:c.2054C>A

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM1 PM2

The NM_001042492.3(NF1):​c.2054C>A​(p.Thr685Asn) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,586 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. T685S) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: NF1 NM_001042492.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 7.43
• 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: Uncertain_significance. The variant received 4 ACMG points.

• PM1: In a hotspot region, there are 3 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 8 benign, 30 uncertain in NM_001042492.3
• PM2: Very rare variant in population databases, with high coverage

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NF1	NM_001042492.3	c.2054C>A	p.Thr685Asn	missense_variant	Exon 18 of 58	ENST00000358273.9	NP_001035957.1
NF1	NM_000267.4	c.2054C>A	p.Thr685Asn	missense_variant	Exon 18 of 57		NP_000258.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NF1	ENST00000358273.9	c.2054C>A	p.Thr685Asn	missense_variant	Exon 18 of 58	1	NM_001042492.3	ENSP00000351015.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461586 Hom.: 0 Cov.: 34 AF XY: 0.00 AC XY: 0 AN XY: 727106

African (AFR) AF: 0.00 AC: 0 AN: 33462

American (AMR) AF: 0.00 AC: 0 AN: 44698

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26128

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86250

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53416

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5762

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111798

Other (OTH) AF: 0.00 AC: 0 AN: 60374

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Neurofibromatosis, type 1 Uncertain:1

Jul 16, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces threonine, which is neutral and polar, with asparagine, which is neutral and polar, at codon 685 of the NF1 protein (p.Thr685Asn). In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. 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. ClinVar contains an entry for this variant (Variation ID: 1366001). This variant has not been reported in the literature in individuals affected with NF1-related conditions. This variant is not present in population databases (gnomAD no frequency). -

NF1-related disorder Uncertain:1

Feb 23, 2024

PreventionGenetics, part of Exact Sciences

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

The NF1 c.2054C>A variant is predicted to result in the amino acid substitution p.Thr685Asn. This variant was reported in an individual with phaeochromocytoma (supplementary table 5 patient #117, Ben Aim et al 2019. PubMed ID: 30877234). This variant has not been reported in a large population database (http://gnomad.broadinstitute.org), indicating this variant is rare. This variant is interpreted as uncertain in ClinVar (https://www.ncbi.nlm.nih.gov/clinvar/variation/1366001/). At this time, the clinical significance of this variant is uncertain due to the absence of conclusive functional and genetic evidence. -

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

Jan 08, 2025

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.T685N variant (also known as c.2054C>A), located in coding exon 18 of the NF1 gene, results from a C to A substitution at nucleotide position 2054. The threonine at codon 685 is replaced by asparagine, an amino acid with similar properties. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be tolerated by in silico analysis. Based on the available evidence, the clinical significance of this variant remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.35
BayesDel_addAF	Uncertain	0.024	T
BayesDel_noAF	Benign	-0.20
CADD	Uncertain	23
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.66	D;.;T
Eigen	Uncertain	0.34
Eigen_PC	Uncertain	0.48
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.91	D;D;D
M_CAP	Pathogenic	0.46	D
MetaRNN	Uncertain	0.51	D;D;D
MetaSVM	Benign	-0.49	T
MutationAssessor	Benign	1.8	L;L;.
PhyloP100		7.4
PrimateAI	Pathogenic	0.87	D
PROVEAN	Benign	-2.1	N;N;N
REVEL	Benign	0.12
Sift	Benign	0.11	T;T;T
Sift4G	Benign	0.23	T;T;T
Polyphen		0.13	B;D;.
Vest4		0.88
MutPred		0.31		Gain of ubiquitination at K686 (P = 0.1497);Gain of ubiquitination at K686 (P = 0.1497);.;
MVP		0.60
MPC		1.7
ClinPred		0.92	D
GERP RS		5.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.36
gMVP		0.75
Mutation Taster		=31/69	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: rs876658190; hg19: chr17-29553505;