17-31338805-G-T

Position:

• chr17-31338805-G-T

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM2 PP2 PP3_Strong

The NM_001042492.3(NF1):​c.6921G>T​(p.Lys2307Asn) variant causes a missense, splice region change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Uncertain significance (★★). Another nucleotide change resulting in same amino acid change has been previously reported as Likely pathogenicin ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. K2307R) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: NF1 NM_001042492.3 missense, splice_region
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 9.25

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 7 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, NF1
• PP3: Splicing scoreres supports a deletorius effect: Scorers claiming Pathogenic: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai. No scorers claiming Uncertain. No scorers claiming Benign.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NF1	NM_001042492.3	c.6921G>T	p.Lys2307Asn	missense_variant, splice_region_variant	46/58	ENST00000358273.9
NF1	NM_000267.3	c.6858G>T	p.Lys2286Asn	missense_variant, splice_region_variant	45/57

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NF1	ENST00000358273.9	c.6921G>T	p.Lys2307Asn	missense_variant, splice_region_variant	46/58	1	NM_001042492.3	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 25

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:2

Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Jun 18, 2021	This sequence change replaces lysine with asparagine at codon 2286 of the NF1 protein (p.Lys2286Asn). The lysine residue is moderately conserved and there is a moderate physicochemical difference between lysine and asparagine. This variant also falls at the last nucleotide of exon 45, which is part of the consensus splice site for this exon. This variant is not present in population databases (ExAC no frequency). 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. This variant disrupts the c.6858G nucleotide in the NF1 gene. Other variant(s) that disrupt this nucleotide have been determined to be pathogenic (PMID: 27074763, Invitae). This suggests that this nucleotide is clinically significant, and that variants that disrupt this position are likely to be disease-causing. Nucleotide substitutions within the consensus splice site are a relatively common cause of aberrant splicing (PMID: 17576681, 9536098). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site, but this prediction has not been confirmed by published transcriptional studies. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. This variant has not been reported in the literature in individuals with NF1-related conditions. ClinVar contains an entry for this variant (Variation ID: 389766). -
Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Mar 15, 2022	- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Sep 26, 2016

The c.6858 G>T variant has not been published as a pathogenic variant, nor has it been reported as a benign variant to our knowledge. The c.6858 G>T variant was not observed in approximately 6,400 individuals of European and African American ancestry in the NHLBI Exome Sequencing Project, indicating it is not a common benign variant in these populations. Several in-silico splice prediction models predict that c.6858 G>T destroys or damages the natural splice donor site and leads to abnormal gene splicing. However, in the absence of RNA/functional studies, the actual effect of this sequence change in this individual is unknown. Therefore, based on the currently available information, it is unclear whether this variant is a pathogenic variant or a rare benign variant. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.27
BayesDel_addAF	Benign	-0.14	T
BayesDel_noAF	Benign	-0.44
CADD	Pathogenic	31
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.58	D;.;T
Eigen	Benign	0.15
Eigen_PC	Uncertain	0.36
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.94	D;D;D
M_CAP	Uncertain	0.089	D
MetaRNN	Benign	0.25	T;T;T
MetaSVM	Benign	-0.86	T
MutationAssessor	Benign	1.7	L;.;.
MutationTaster	Benign	1.0	D;D;D;D
PrimateAI	Uncertain	0.74	T
PROVEAN	Benign	-2.3	N;N;N
REVEL	Benign	0.097
Sift	Benign	0.050	D;T;T
Sift4G	Benign	0.15	T;T;T
Polyphen		0.11	B;B;.
Vest4		0.59
MutPred		0.45		Loss of methylation at K2307 (P = 0.0067);.;.;
MVP		0.52
MPC		1.5
ClinPred		0.76	D
GERP RS		5.8
Varity_R		0.42
gMVP		0.57

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.96
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.99		Position offset: 0

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

Publications

LitVar

Other links and lift over

dbSNP: rs1057523533; hg19: chr17-29665823;