17-31232830-A-T

Variant names:

• chr17-31232830-A-T
• rs1187097568
• NM_001042492.3:c.3445A>T

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM1 PM2 PM5

The NM_001042492.3(NF1):​c.3445A>T​(p.Met1149Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 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. M1149R) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 31)
• Consequence: NF1 NM_001042492.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 8.88
• Publications: 0 publications found

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]

NF1 Gene-Disease associations (from GenCC):

• neurofibromatosis type 1

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, PanelApp Australia, G2P, Genomics England PanelApp
• neurofibromatosis-Noonan syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Genomics England PanelApp, PanelApp Australia
• Moyamoya disease

  Inheritance: AD Classification: MODERATE Submitted by: Genomics England PanelApp
• hereditary pheochromocytoma-paraganglioma

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• familial ovarian cancer

  Inheritance: AD Classification: NO_KNOWN Submitted by: ClinGen

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PM1: In a hotspot region, there are 13 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 5 benign, 31 uncertain in NM_001042492.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr17-31232831-T-G is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 429001.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NF1	NM_001042492.3	c.3445A>T	p.Met1149Leu	missense_variant	Exon 26 of 58	ENST00000358273.9	NP_001035957.1
NF1	NM_000267.4	c.3445A>T	p.Met1149Leu	missense_variant	Exon 26 of 57		NP_000258.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NF1	ENST00000358273.9	c.3445A>T	p.Met1149Leu	missense_variant	Exon 26 of 58	1	NM_001042492.3	ENSP00000351015.4

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 31

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Neurofibromatosis, type 1 Uncertain:1

Mar 17, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces methionine with leucine at codon 1149 of the NF1 protein (p.Met1149Leu). The methionine residue is moderately conserved and there is a small physicochemical difference between methionine and leucine. This variant is not present in population databases (ExAC no frequency). This variant has been observed in individual(s) with clinical features of NF1-related conditions (PMID: 31595648). 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: "Possibly Damaging"; Align-GVGD: "Class C0"). This variant disrupts the p.Met1149 amino acid residue in NF1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 27322474, 16944272, 23656349, 24711935, 28706617). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.70
BayesDel_addAF	Uncertain	0.043	T
BayesDel_noAF	Benign	-0.18
CADD	Uncertain	23
DANN	Benign	0.97
DEOGEN2	Pathogenic	0.81	D;.;T
Eigen	Uncertain	0.22
Eigen_PC	Uncertain	0.36
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.93	D;D;D
M_CAP	Pathogenic	0.67	D
MetaRNN	Uncertain	0.66	D;D;D
MetaSVM	Benign	-0.99	T
MutationAssessor	Benign	1.1	L;L;.
PhyloP100		8.9
PrimateAI	Pathogenic	0.89	D
PROVEAN	Uncertain	-2.4	N;N;N
REVEL	Uncertain	0.36
Sift	Benign	0.11	T;T;T
Sift4G	Pathogenic	0.0	D;D;D
Polyphen		0.048	B;B;.
Vest4		0.79
MutPred		0.67		Loss of catalytic residue at M1149 (P = 0.0032);Loss of catalytic residue at M1149 (P = 0.0032);.;
MVP		0.72
MPC		1.1
ClinPred		0.85	D
GERP RS		5.5
Varity_R		0.38
gMVP		0.79
Mutation Taster		=12/88	disease causing

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

Other links and lift over

dbSNP: rs1187097568; hg19: chr17-29559848;