17-31227590-A-C

Variant names:

• chr17-31227590-A-C
• rs745498566
• NM_001042492.3:c.2393A>C

Variant summary

Our verdict is Likely pathogenic. The variant received 7 ACMG points: 7P and 0B. PM1 PM2 PM5 PP3

The NM_001042492.3(NF1):​c.2393A>C​(p.Lys798Thr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,480 control chromosomes in the GnomAD database, with no homozygous occurrence. 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. K798Q) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: NF1 NM_001042492.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 8.72
• Publications: 2 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 7 ACMG points.

• PM1: In a hotspot region, there are 2 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 3 benign, 22 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 chr17-31227589-A-C is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 431607.Status of the report is no_assertion_criteria_provided, 0 stars.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.815

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
NF1	NM_001042492.3	c.2393A>C	p.Lys798Thr	missense_variant	Exon 20 of 58	ENST00000358273.9	NP_001035957.1
NF1	NM_000267.4	c.2393A>C	p.Lys798Thr	missense_variant	Exon 20 of 57		NP_000258.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
NF1	ENST00000358273.9	c.2393A>C	p.Lys798Thr	missense_variant	Exon 20 of 58	1	NM_001042492.3	ENSP00000351015.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461480 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727058

African (AFR) AF: 0.00 AC: 0 AN: 33450

American (AMR) AF: 0.00 AC: 0 AN: 44700

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26110

East Asian (EAS) AF: 0.00 AC: 0 AN: 39666

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53410

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5762

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111770

Other (OTH) AF: 0.00 AC: 0 AN: 60358

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

Jan 08, 2020

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. ClinVar contains an entry for this variant (Variation ID: 527587). This variant is not present in population databases (ExAC no frequency). This sequence change replaces lysine with threonine at codon 798 of the NF1 protein (p.Lys798Thr). The lysine residue is moderately conserved and there is a moderate physicochemical difference between lysine and threonine. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.72
BayesDel_addAF	Pathogenic	0.17	D
BayesDel_noAF	Uncertain	0.010
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.87	D;.;T
Eigen	Uncertain	0.65
Eigen_PC	Uncertain	0.65
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.96	D;D;D
M_CAP	Pathogenic	0.73	D
MetaRNN	Pathogenic	0.82	D;D;D
MetaSVM	Benign	-1.2	T
MutationAssessor	Uncertain	2.1	M;M;.
PhyloP100		8.7
PrimateAI	Pathogenic	0.82	D
PROVEAN	Pathogenic	-4.4	D;D;D
REVEL	Uncertain	0.45
Sift	Uncertain	0.0060	D;D;D
Sift4G	Uncertain	0.0020	D;D;D
Polyphen		0.97	D;D;.
Vest4		0.79
MutPred		0.32		Loss of ubiquitination at K798 (P = 0.0039);Loss of ubiquitination at K798 (P = 0.0039);.;
MVP		0.80
MPC		1.9
ClinPred		1.0	D
GERP RS		4.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.50
gMVP		0.57
Mutation Taster		=4/96	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: rs745498566; hg19: chr17-29554608;