17-31326110-T-C

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PM5 PP2 PP3_Moderate

The NM_001042492.3(NF1):c.5126T>C(p.Ile1709Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000657 in 152,176 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 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. I1709V) has been classified as Uncertain significance.

• Frequency: Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
• Consequence: NF1 NM_001042492.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 7.63

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 9 ACMG points.

• PM1: In a domain CRAL-TRIO (size 158) in uniprot entity NF1_HUMAN there are 65 pathogenic changes around while only 11 benign (86%) 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 chr17-31326110-TA-G is described in ClinVar as [Pathogenic]. Clinvar id is 3027388.Status of the report is criteria_provided_single_submitter, 1 stars.
• PP2: Missense variant where missense usually causes diseases, NF1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.865

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NF1	NM_001042492.3	c.5126T>C	p.Ile1709Thr	missense_variant	37/58	ENST00000358273.9
NF1	NM_000267.3	c.5063T>C	p.Ile1688Thr	missense_variant	36/57

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NF1	ENST00000358273.9	c.5126T>C	p.Ile1709Thr	missense_variant	37/58	1	NM_001042492.3	P1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152176 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000241

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD4 exome Cov.: 32

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152176 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 74340

Gnomad4 AFR AF: 0.0000241

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Bravo AF: 0.00000378

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Neurofibromatosis, type 1 Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Nov 19, 2023	This sequence change replaces isoleucine, which is neutral and non-polar, with threonine, which is neutral and polar, at codon 1688 of the NF1 protein (p.Ile1688Thr). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with NF1-related conditions. ClinVar contains an entry for this variant (Variation ID: 233296). 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) performed at Invitae indicates that this missense variant is expected to disrupt NF1 protein function with a positive predictive value of 95%. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. 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. -
Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Mar 15, 2022	- -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Aug 07, 2015

The p.I1709T variant (also known as c.5126T>C), located in coding exon 37 of the NF1 gene, results from a T to C substitution at nucleotide position 5126. The isoleucine at codon 1709 is replaced by threonine, an amino acid with similar properties. 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. To date, this alteration has been detected with an allele frequency of approximately 0.002% (greater than 55000alleles tested) in our clinical cohort.This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be deleterious by in silico analysis.Since supporting evidence is limited at this time, the clinical significance of p.I1709Tremains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.14
BayesDel_addAF	Pathogenic	0.35	D
BayesDel_noAF	Pathogenic	0.27
Cadd	Pathogenic	28
Dann	Uncertain	1.0
DEOGEN2	Pathogenic	0.84	D;.;T
Eigen	Pathogenic	0.74
Eigen_PC	Pathogenic	0.74
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.96	D;D;D
M_CAP	Pathogenic	0.85	D
MetaRNN	Pathogenic	0.86	D;D;D
MetaSVM	Uncertain	-0.13	T
MutationAssessor	Uncertain	2.0	M;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.84	D
PROVEAN	Uncertain	-3.7	D;D;D
REVEL	Pathogenic	0.76
Sift	Uncertain	0.0020	D;D;D
Sift4G	Uncertain	0.0020	D;D;D
Polyphen		0.99	D;D;.
Vest4		0.96
MutPred		0.53		Loss of stability (P = 9e-04);.;.;
MVP		0.93
MPC		1.9
ClinPred		0.98	D
GERP RS		5.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.79
gMVP		0.84

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.21		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.21		Position offset: 3

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

Publications

LitVar

Other links and lift over

dbSNP: rs876660316; hg19: chr17-29653128;