rs876658354

Positions:

• chr17-31159039-T-A
• chr17-31159039-T-C

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.234T>A​(p.Asn78Lys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000687 in 1,456,330 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. N78S) 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, multiple submitters, no conflicts U:6
• Conservation: PhyloP100: 2.79

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, 13 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=0.36014804).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NF1	NM_001042492.3	c.234T>A	p.Asn78Lys	missense_variant	3/58	ENST00000358273.9
NF1	NM_000267.3	c.234T>A	p.Asn78Lys	missense_variant	3/57
NF1	NM_001128147.3	c.234T>A	p.Asn78Lys	missense_variant	3/15

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NF1	ENST00000358273.9	c.234T>A	p.Asn78Lys	missense_variant	3/58	1	NM_001042492.3	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.00000399 AC: 1 AN: 250832 Hom.: 0 AF XY: 0.00000737 AC XY: 1 AN XY: 135678

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 SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000164

GnomAD4 exome AF: 6.87e-7 AC: 1 AN: 1456330 Hom.: 0 Cov.: 28 AF XY: 0.00000138 AC XY: 1 AN XY: 724864

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

Alfa AF: 0.0000508 Hom.: 0

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Neurofibromatosis, type 1 Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Mar 15, 2022	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Invitae	Dec 03, 2022	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. 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) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on NF1 protein function. ClinVar contains an entry for this variant (Variation ID: 230049). This variant has not been reported in the literature in individuals affected with NF1-related conditions. This variant is present in population databases (no rsID available, gnomAD no frequency). This sequence change replaces asparagine, which is neutral and polar, with lysine, which is basic and polar, at codon 78 of the NF1 protein (p.Asn78Lys). -

Neurofibromatosis, type 1;C0349639:Juvenile myelomonocytic leukemia;C0553586:Café-au-lait macules with pulmonary stenosis;C1834235:Neurofibromatosis, familial spinal;C2931482:Neurofibromatosis-Noonan syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Fulgent Genetics, Fulgent Genetics

Aug 19, 2021

- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Feb 23, 2023

In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

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

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jan 31, 2020

The c.234T>A (p.N78K) alteration is located in exon 3 (coding exon 3) of the NF1 gene. This alteration results from a T to A substitution at nucleotide position 234, causing the asparagine (N) at amino acid position 78 to be replaced by a lysine (K). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Hereditary cancer-predisposing syndrome Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Jan 16, 2015

The p.N78K variant (also known as c.234T>A), located in coding exon 3 of the NF1 gene, results from a T to A substitution at nucleotide position 234. The asparagine at codon 78 is replaced by lysine, 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 6501 samples (13002 alleles) with coverage at this position. To date, this alteration has been detected with an allele frequency of approximately 0.003% (greater than 30000 alleles tested) in our clinical cohort. This amino acid position is highly conserved in available vertebrate species. In addition, this alteration is predicted to be benign and deleterious by PolyPhen and SIFT in silico analyses, respectively. Since supporting evidence is limited at this time, the clinical significance of p.N78K remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.94
BayesDel_addAF	Benign	-0.15	T
BayesDel_noAF	Benign	-0.45
CADD	Benign	23
DANN	Benign	0.87
Eigen	Uncertain	0.55
Eigen_PC	Uncertain	0.53
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Uncertain	0.96	D;D;D;D
M_CAP	Pathogenic	0.61	D
MetaRNN	Benign	0.36	T;T;T;T
MetaSVM	Benign	-1.1	T
MutationAssessor	Benign	1.3	L;L;L;L
MutationTaster	Benign	0.70	D;D;D
PrimateAI	Pathogenic	0.86	D
Polyphen		0.99	D;P;D;.
Vest4		0.79, 0.78, 0.86
MutPred		0.27		Gain of ubiquitination at N78 (P = 0.0211);Gain of ubiquitination at N78 (P = 0.0211);Gain of ubiquitination at N78 (P = 0.0211);Gain of ubiquitination at N78 (P = 0.0211);
MVP		0.48
MPC		1.8
ClinPred		0.93	D
GERP RS		5.1
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.38
gMVP		0.77

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs876658354; hg19: chr17-29486057;