rs144178015

Positions:

• chr17-31360548-C-A
• chr17-31360548-C-G
• chr17-31360548-C-T

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 3P and 1B. PM2 PP2 BP4

The NM_001042492.3(NF1):​c.8222C>A​(p.Thr2741Lys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 12/21 in silico tools predict 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. T2741M) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: NF1 NM_001042492.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:4
• Conservation: PhyloP100: 2.86

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 Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, NF1
• BP4: Computational evidence support a benign effect (MetaRNN=0.29672098).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NF1	NM_001042492.3	c.8222C>A	p.Thr2741Lys	missense_variant	57/58	ENST00000358273.9
NF1	NM_000267.3	c.8159C>A	p.Thr2720Lys	missense_variant	56/57

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NF1	ENST00000358273.9	c.8222C>A	p.Thr2741Lys	missense_variant	57/58	1	NM_001042492.3	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Neurofibromatosis, type 1 Uncertain:3

Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Mar 15, 2022	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Center for Human Genetics, Inc, Center for Human Genetics, Inc	Nov 01, 2016	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Aug 03, 2021	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. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may create or strengthen a splice site. 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. ClinVar contains an entry for this variant (Variation ID: 547702). This variant has not been reported in the literature in individuals affected with NF1-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces threonine with lysine at codon 2720 of the NF1 protein (p.Thr2720Lys). The threonine residue is moderately conserved and there is a moderate physicochemical difference between threonine and lysine. -

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

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

May 30, 2022

The p.T2720K variant (also known as c.8159C>A), located in coding exon 56 of the NF1 gene, results from a C to A substitution at nucleotide position 8159. The threonine at codon 2720 is replaced by lysine, an amino acid with similar properties. This amino acid position is conserved. 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	Benign	0.18
BayesDel_addAF	Benign	-0.14	T
BayesDel_noAF	Benign	-0.44
CADD	Uncertain	25
DANN	Benign	0.97
DEOGEN2	Uncertain	0.78	D;.;T
Eigen	Benign	-0.023
Eigen_PC	Benign	0.17
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Uncertain	0.91	D;D;D
M_CAP	Benign	0.044	D
MetaRNN	Benign	0.30	T;T;T
MetaSVM	Benign	-1.0	T
MutationAssessor	Benign	1.7	L;.;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.77	T
PROVEAN	Uncertain	-2.9	D;D;D
REVEL	Benign	0.059
Sift	Uncertain	0.028	D;D;D
Sift4G	Uncertain	0.049	D;D;T
Polyphen		0.0010	B;B;.
Vest4		0.38
MutPred		0.39		Gain of methylation at T2741 (P = 0.0098);.;.;
MVP		0.39
MPC		0.62
ClinPred		0.95	D
GERP RS		5.3
Varity_R		0.29
gMVP		0.84

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

Publications

LitVar

Other links and lift over

dbSNP: rs144178015; hg19: chr17-29687566;