NM_000138.5:c.6801C>G

Variant names:

• chr15-48430741-G-C
• rs886051245
• NM_000138.5:c.6801C>G

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5

The NM_000138.5(FBN1):​c.6801C>G​(p.Asn2267Lys) variant causes a missense change involving the alteration of a non-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 Conflicting classifications of pathogenicity (no stars). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. N2267I) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:1
• Conservation: PhyloP100: 2.45

Genes affected

FBN1 (HGNC:3603): (fibrillin 1) This gene encodes a member of the fibrillin family of proteins. The encoded preproprotein is proteolytically processed to generate two proteins including the extracellular matrix component fibrillin-1 and the protein hormone asprosin. Fibrillin-1 is an extracellular matrix glycoprotein that serves as a structural component of calcium-binding microfibrils. These microfibrils provide force-bearing structural support in elastic and nonelastic connective tissue throughout the body. Asprosin, secreted by white adipose tissue, has been shown to regulate glucose homeostasis. Mutations in this gene are associated with Marfan syndrome and the related MASS phenotype, as well as ectopia lentis syndrome, Weill-Marchesani syndrome, Shprintzen-Goldberg syndrome and neonatal progeroid syndrome. [provided by RefSeq, Apr 2016]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PM1: In a disulfide_bond (size 16) in uniprot entity FBN1_HUMAN there are 11 pathogenic changes around while only 0 benign (100%) in NM_000138.5
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr15-48430742-T-A is described in Lovd as [Likely_pathogenic].
• PP2: Missense variant in the FBN1 gene, where missense mutations are typically associated with disease (based on misZ statistic). The gene has 1311 curated pathogenic missense variants (we use a threshold of 10). The gene has 112 curated benign missense variants. Gene score misZ: 5.0644 (above the threshold of 3.09). Trascript score misZ: 8.1787 (above the threshold of 3.09). GenCC associations: The gene is linked to MASS syndrome, Weill-Marchesani syndrome, geleophysic dysplasia, Shprintzen-Goldberg syndrome, Acromicric dysplasia, familial thoracic aortic aneurysm and aortic dissection, progeroid and marfanoid aspect-lipodystrophy syndrome, ectopia lentis 1, isolated, autosomal dominant, Marfan syndrome, Weill-Marchesani syndrome 2, dominant, isolated ectopia lentis, neonatal Marfan syndrome, stiff skin syndrome.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.97
• PP5: Variant 15-48430741-G-C is Pathogenic according to our data. Variant chr15-48430741-G-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 457252.We mark this variant Likely_pathogenic, oryginal submissions are: {Likely_pathogenic=1, Uncertain_significance=1, Pathogenic=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FBN1	NM_000138.5	c.6801C>G	p.Asn2267Lys	missense_variant	Exon 56 of 66	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.6801C>G	p.Asn2267Lys	missense_variant	Exon 55 of 65		NP_001393645.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FBN1	ENST00000316623.10	c.6801C>G	p.Asn2267Lys	missense_variant	Exon 56 of 66	1	NM_000138.5	ENSP00000325527.5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 32

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Marfan syndrome Pathogenic:1

Mar 01, 2021

Centre of Medical Genetics, University of Antwerp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: research

PM2, PS6, PP4 -

Marfan syndrome;C4707243:Familial thoracic aortic aneurysm and aortic dissection Pathogenic:1

Feb 09, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces asparagine, which is neutral and polar, with lysine, which is basic and polar, at codon 2267 of the FBN1 protein (p.Asn2267Lys). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individuals with clinical features of Marfan syndrome (PMID: 25907466; Invitae). ClinVar contains an entry for this variant (Variation ID: 457252). 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) performed at Invitae indicates that this missense variant is expected to disrupt FBN1 protein function with a positive predictive value of 95%. For these reasons, this variant has been classified as Pathogenic. -

not provided Uncertain:1

Nov 17, 2016

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: The FBN1 c.6801C>G (p.Asn2267Lys) variant involves the alteration of a conserved nucleotide. This variant is located within the calcium-binding EGF-like domain. 4/4 in silico tools predict a damaging outcome for this variant (SNPs&GO not captured due to low reliability index). This variant has been reported in at least 1 patients with classical MFS and is absent from 121328 control chromosomes. In addition, another alteration of this codon, c.6800A>T (p.N2267I) was reported in a pt with Classical MFS. Taken together, this variant is classified as VUS-Possibly Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.25	D
BayesDel_noAF	Uncertain	0.12
CADD	Uncertain	25
DANN	Uncertain	1.0
Eigen	Pathogenic	0.94
Eigen_PC	Pathogenic	0.85
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.99	D
M_CAP	Pathogenic	0.91	D
MetaRNN	Pathogenic	0.97	D
MetaSVM	Pathogenic	1.0	D
PrimateAI	Uncertain	0.69	T
PROVEAN	Pathogenic	-5.0	D
REVEL	Pathogenic	0.81
Sift	Uncertain	0.0020	D
Sift4G	Uncertain	0.0020	D
Vest4		0.88
MutPred		0.80		Gain of methylation at N2267 (P = 0.0019);
MVP		0.96
MPC		1.5
ClinPred		0.98	D
GERP RS		5.9

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: rs886051245; hg19: chr15-48722938;