17-31156029-C-T

Variant names:

• chr17-31156029-C-T
• rs199966218
• NM_001042492.3:c.107C>T

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 4P and 2B. PM1 PM2 BP4_Moderate

The NM_001042492.3(NF1):​c.107C>T​(p.Thr36Ile) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,258 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign 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. T36S) has been classified as Likely benign.

• 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: 5.73
• Publications: 7 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 2 ACMG points.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 5 benign, 30 uncertain in NM_001042492.3
• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.14080805).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NF1	NM_001042492.3	c.107C>T	p.Thr36Ile	missense_variant	Exon 2 of 58	ENST00000358273.9	NP_001035957.1
NF1	NM_000267.4	c.107C>T	p.Thr36Ile	missense_variant	Exon 2 of 57		NP_000258.1
NF1	NM_001128147.3	c.107C>T	p.Thr36Ile	missense_variant	Exon 2 of 15		NP_001121619.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NF1	ENST00000358273.9	c.107C>T	p.Thr36Ile	missense_variant	Exon 2 of 58	1	NM_001042492.3	ENSP00000351015.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD2 exomes AF: 0.00000398 AC: 1 AN: 251066 AF XY: 0.00000737

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000882

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461258 Hom.: 0 Cov.: 33 AF XY: 0.00000138 AC XY: 1 AN XY: 726922

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR) AF: 0.00 AC: 0 AN: 33456

American (AMR) AF: 0.00 AC: 0 AN: 44710

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26110

East Asian (EAS) AF: 0.00 AC: 0 AN: 39600

South Asian (SAS) AF: 0.00 AC: 0 AN: 86240

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53378

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 9.00e-7 AC: 1 AN: 1111646

Other (OTH) AF: 0.00 AC: 0 AN: 60354

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 32

Alfa AF: 0.00 Hom.: 0

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

Mar 15, 2022

Genome-Nilou Lab

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

May 06, 2024

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 isoleucine, which is neutral and non-polar, at codon 36 of the NF1 protein (p.Thr36Ile). This variant is present in population databases (no rsID available, gnomAD 0.002%). 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: 481973). 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 not expected to disrupt NF1 protein function with a negative predictive value of 95%. 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. -

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

Dec 05, 2022

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The p.T36I variant (also known as c.107C>T), located in coding exon 2 of the NF1 gene, results from a C to T substitution at nucleotide position 107. The threonine at codon 36 is replaced by isoleucine, 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. Since supporting evidence is limited at this time, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.38
BayesDel_addAF	Benign	0.0093	T
BayesDel_noAF	Benign	-0.22
CADD	Uncertain	23
DANN	Benign	0.77
DEOGEN2	Uncertain	0.48	.;T;.;.
Eigen	Benign	-0.023
Eigen_PC	Benign	0.15
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.94	D;D;D;D
M_CAP	Benign	0.079	D
MetaRNN	Benign	0.14	T;T;T;T
MetaSVM	Benign	-0.98	T
MutationAssessor	Benign	0.98	L;L;L;L
PhyloP100		5.7
PrimateAI	Pathogenic	0.87	D
PROVEAN	Benign	-0.70	.;N;N;N
REVEL	Benign	0.17
Sift	Benign	0.47	.;T;T;T
Sift4G	Benign	0.66	.;T;T;T
Polyphen		0.42	B;B;B;.
Vest4		0.69, 0.68, 0.72
MutPred		0.24		Gain of sheet (P = 0.0101);Gain of sheet (P = 0.0101);Gain of sheet (P = 0.0101);Gain of sheet (P = 0.0101);
MVP		0.79
MPC		0.79
ClinPred		0.29	T
GERP RS		5.0
Varity_R		0.13
gMVP		0.54
Mutation Taster		=58/42	polymorphism

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		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: rs199966218; hg19: chr17-29483047; COSMIC: COSV108185255; COSMIC: COSV108185255;