rs1555594471

Positions:

• chr17-31095313-GC-TT

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PM2 PP2

The NM_001042492.3(NF1):​c.4_5delinsTT​(p.Ala2Phe) variant causes a missense change. 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. A2D) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 30)
• Consequence: NF1 NM_001042492.3 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:5
• Conservation: PhyloP100: 5.54

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]

MIR4733HG (HGNC:55332): (MIR4733 host gene)

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM1: In a modified_residue N-acetylalanine (size 0) in uniprot entity NF1_HUMAN
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in gene, where missense usually causes diseases (based on misZ statistic), NF1. . Gene score misZ 6.5427 (greater than the threshold 3.09). Trascript score misZ 8.4054 (greater than threshold 3.09). GenCC has associacion of gene with neurofibromatosis, familial spinal, hereditary pheochromocytoma-paraganglioma, neurofibromatosis type 1, Watson syndrome, neurofibromatosis-Noonan syndrome, Moyamoya disease, familial ovarian cancer.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
NF1	NM_001042492.3	c.4_5delinsTT	p.Ala2Phe	missense_variant	1/58	ENST00000358273.9
NF1	NM_000267.3	c.4_5delinsTT	p.Ala2Phe	missense_variant	1/57
NF1	NM_001128147.3	c.4_5delinsTT	p.Ala2Phe	missense_variant	1/15

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
NF1	ENST00000358273.9	c.4_5delinsTT	p.Ala2Phe	missense_variant	1/58	1	NM_001042492.3	P1
MIR4733HG	ENST00000583377.1	n.137_138delinsAA		non_coding_transcript_exon_variant	1/3	2

Frequencies

GnomAD3 genomes Cov.: 30

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 30

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Neurofibromatosis, type 1 Uncertain:2

Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Nov 21, 2023	This sequence change replaces alanine, which is neutral and non-polar, with phenylalanine, which is neutral and non-polar, at codon 2 of the NF1 protein (p.Ala2Phe). Information on the frequency of this variant in the gnomAD database is not available, as this variant may be reported differently in the database. This variant has not been reported in the literature in individuals affected with NF1-related conditions. ClinVar contains an entry for this variant (Variation ID: 480205). An algorithm developed to predict the effect of missense changes on protein structure and function (PolyPhen-2) suggests that this variant is likely to be tolerated. 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. -
Uncertain significance, criteria provided, single submitter	clinical testing	Genome-Nilou Lab	Mar 15, 2022	- -

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Aug 07, 2023

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -

Juvenile myelomonocytic leukemia Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Baylor Genetics

Dec 29, 2023

- -

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

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Feb 08, 2024

The c.4_5delGCinsTT variant (also known as p.A2F), located in coding exon 1 of the NF1 gene, results from an in-frame deletion of GC and insertion of TT at nucleotide positions 4 to 5. This results in the substitution of the alanine residue for a phenylalanine residue at codon 2, an amino acid with dissimilar properties. This variant has been detected in the homozygous state in a 66-year-old individual with no reported features of neurofibromatosis type 1 (Ambry internal data). This amino acid position is well conserved on limited sequence alignment. In addition, the in silico prediction for this alteration is inconclusive (Choi Y et al. PLoS ONE. 2012; 7(10):e46688). Based on the available evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Splicing

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1555594471; hg19: chr17-29422331;