rs1555533307

chr17-31325924-A-Cchr17-31325924-A-T

Variant summary

Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PM1 PM2 PP2 PP3_Moderate

The NM_001042492.3(NF1):c.4940A>C(p.His1647Pro) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic 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. H1647Y) 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:2
• Conservation: PhyloP100: 8.91

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.

• PM1: In a hotspot region, there are 4 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 1 benign, 16 uncertain in NM_001042492.3
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant where missense usually causes diseases, NF1
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.888

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NF1	NM_001042492.3	c.4940A>C	p.His1647Pro	missense_variant	37/58	ENST00000358273.9
NF1	NM_000267.3	c.4877A>C	p.His1626Pro	missense_variant	36/57

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NF1	ENST00000358273.9	c.4940A>C	p.His1647Pro	missense_variant	37/58	1	NM_001042492.3	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Neurofibromatosis, type 1 Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Dec 01, 2017

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 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 disease. This variant is not present in population databases (ExAC no frequency). This sequence change replaces histidine with proline at codon 1626 of the NF1 protein (p.His1626Pro). The histidine residue is moderately conserved and there is a moderate physicochemical difference between histidine and proline. -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Oct 06, 2022

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Observed in a patient with clinically suspected neurofibromatosis type 1 in published literature (Wu-Chou et al., 2018); Also known as c.4940 A>C p.(His1647Pro); This variant is associated with the following publications: (PMID: 30290804) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.97
BayesDel_addAF	Pathogenic	0.33	D
BayesDel_noAF	Pathogenic	0.23
Cadd	Pathogenic	27
Dann	Uncertain	0.98
DEOGEN2	Pathogenic	0.87	D;.;T
Eigen	Uncertain	0.55
Eigen_PC	Uncertain	0.62
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.92	D;D;D
M_CAP	Pathogenic	0.75	D
MetaRNN	Pathogenic	0.89	D;D;D
MetaSVM	Benign	-0.40	T
MutationAssessor	Uncertain	2.4	M;.;.
MutationTaster	Benign	1.0	D;D
PrimateAI	Pathogenic	0.88	D
PROVEAN	Pathogenic	-8.3	D;D;D
REVEL	Uncertain	0.50
Sift	Uncertain	0.020	D;D;D
Sift4G	Uncertain	0.0020	D;D;D
Polyphen		0.53	P;D;.
Vest4		0.83
MutPred		0.41		Gain of glycosylation at T1648 (P = 0.0469);.;.;
MVP		0.85
MPC		2.1
ClinPred		0.99	D
GERP RS		5.8
Varity_R		0.98
gMVP		0.96

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: rs1555533307; hg19: chr17-29652942;