17-31159040-T-G

Position:

• chr17-31159040-T-G

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 5P and 1B. PM1 PM2 PP2 BP4

The NM_001042492.3(NF1):​c.235T>G​(p.Leu79Val) variant causes a missense change. The variant allele was found at a frequency of 0.000000686 in 1,456,760 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. L79F) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: NF1 NM_001042492.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 5.56

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 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 1 benign, 14 uncertain in NM_001042492.3
• 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=0.32939258).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NF1	NM_001042492.3	c.235T>G	p.Leu79Val	missense_variant	3/58	ENST00000358273.9
NF1	NM_000267.3	c.235T>G	p.Leu79Val	missense_variant	3/57
NF1	NM_001128147.3	c.235T>G	p.Leu79Val	missense_variant	3/15

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NF1	ENST00000358273.9	c.235T>G	p.Leu79Val	missense_variant	3/58	1	NM_001042492.3	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.86e-7 AC: 1 AN: 1456760 Hom.: 0 Cov.: 28 AF XY: 0.00000138 AC XY: 1 AN XY: 725038

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.03e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Neurofibromatosis, type 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Mar 31, 2020

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 missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Probably Damaging"; Align-GVGD: "Class C0"). This variant has not been reported in the literature in individuals with NF1-related conditions. This variant is not present in population databases (ExAC no frequency). This sequence change replaces leucine with valine at codon 79 of the NF1 protein (p.Leu79Val). The leucine residue is highly conserved and there is a small physicochemical difference between leucine and valine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.58
BayesDel_addAF	Benign	-0.027	T
BayesDel_noAF	Benign	-0.28
CADD	Uncertain	25
DANN	Benign	0.94
Eigen	Uncertain	0.57
Eigen_PC	Uncertain	0.56
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Uncertain	0.97	D;D;D;D
M_CAP	Pathogenic	0.50	D
MetaRNN	Benign	0.33	T;T;T;T
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	1.8	L;L;L;L
MutationTaster	Benign	0.98	D;D;D
PrimateAI	Pathogenic	0.80	T
Polyphen		0.97	D;D;D;.
Vest4		0.63, 0.64, 0.72
MutPred		0.26		Loss of helix (P = 0.0558);Loss of helix (P = 0.0558);Loss of helix (P = 0.0558);Loss of helix (P = 0.0558);
MVP		0.45
MPC		1.6
ClinPred		0.86	D
GERP RS		5.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.21
gMVP		0.43

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: rs764855221; hg19: chr17-29486058;