NM_000138.5:c.6832C>G

Variant names:

• chr15-48430710-G-C
• rs363835
• NM_000138.5:c.6832C>G

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 3P and 7B. PM1 PP2 BP4_Moderate BP6 BS1

The NM_000138.5(FBN1):​c.6832C>G​(p.Pro2278Ala) variant causes a missense change. The variant allele was found at a frequency of 0.0000948 in 1,613,830 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign 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. P2278S) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.00049 (0 hom., cov: 32)
  • Exomes 𝑓: 0.000054 (0 hom.)
• Consequence: FBN1 NM_000138.5 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1 B:8
• Conservation: PhyloP100: 6.88
• Publications: 12 publications found

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]

FBN1 Gene-Disease associations (from GenCC):

• familial thoracic aortic aneurysm and aortic dissection

  Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: ClinGen, Orphanet
• Marfan syndrome

  Inheritance: AD, AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Genomics England PanelApp, ClinGen, G2P, PanelApp Australia, Orphanet, Ambry Genetics
• Acromicric dysplasia

  Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Ambry Genetics
• progeroid and marfanoid aspect-lipodystrophy syndrome

  Inheritance: AD Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, Orphanet
• stiff skin syndrome

  Inheritance: AD Classification: STRONG, LIMITED Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
• Weill-Marchesani syndrome 2, dominant

  Inheritance: AD Classification: STRONG Submitted by: G2P, Labcorp Genetics (formerly Invitae)
• geleophysic dysplasia

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• isolated ectopia lentis

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• neonatal Marfan syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• Weill-Marchesani syndrome

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• ectopia lentis 1, isolated, autosomal dominant

  Inheritance: AD Classification: LIMITED Submitted by: G2P
• Shprintzen-Goldberg syndrome

  Inheritance: AD, Unknown Classification: LIMITED, NO_KNOWN Submitted by: ClinGen, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Likely_benign. The variant received -4 ACMG points.

• PM1: In a hotspot region, there are 9 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 5 benign, 13 uncertain in NM_000138.5
• 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 Marfan syndrome, Weill-Marchesani syndrome 2, dominant, progeroid and marfanoid aspect-lipodystrophy syndrome, geleophysic dysplasia, Shprintzen-Goldberg syndrome, stiff skin syndrome, familial thoracic aortic aneurysm and aortic dissection, isolated ectopia lentis, ectopia lentis 1, isolated, autosomal dominant, Acromicric dysplasia, neonatal Marfan syndrome, Weill-Marchesani syndrome.
• BP4: Computational evidence support a benign effect (MetaRNN=0.17363772).
• BP6: Variant 15-48430710-G-C is Benign according to our data. Variant chr15-48430710-G-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 380285.
• BS1: Variant frequency is greater than expected in population afr. GnomAd4 allele frequency = 0.000486 (74/152228) while in subpopulation AFR AF = 0.00178 (74/41518). AF 95% confidence interval is 0.00146. There are 0 homozygotes in GnomAd4. There are 29 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FBN1	NM_000138.5	c.6832C>G	p.Pro2278Ala	missense_variant	Exon 56 of 66	ENST00000316623.10	NP_000129.3
FBN1	NM_001406716.1	c.6832C>G	p.Pro2278Ala	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.6832C>G	p.Pro2278Ala	missense_variant	Exon 56 of 66	1	NM_000138.5	ENSP00000325527.5

Frequencies

GnomAD3 genomes AF: 0.000486 AC: 74 AN: 152110 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00179

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.000107 AC: 27 AN: 251282 AF XY: 0.0000663

Gnomad AFR exome AF: 0.00166

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000541 AC: 79 AN: 1461602 Hom.: 0 Cov.: 32 AF XY: 0.0000481 AC XY: 35 AN XY: 727122

African (AFR) AF: 0.00212 AC: 71 AN: 33458

American (AMR) AF: 0.00 AC: 0 AN: 44714

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26122

East Asian (EAS) AF: 0.00 AC: 0 AN: 39690

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53404

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111818

Other (OTH) AF: 0.000116 AC: 7 AN: 60370

GnomAD4 genome AF: 0.000486 AC: 74 AN: 152228 Hom.: 0 Cov.: 32 AF XY: 0.000390 AC XY: 29 AN XY: 74420

African (AFR) AF: 0.00178 AC: 74 AN: 41518

American (AMR) AF: 0.00 AC: 0 AN: 15284

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3468

East Asian (EAS) AF: 0.00 AC: 0 AN: 5184

South Asian (SAS) AF: 0.00 AC: 0 AN: 4824

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10606

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68024

Other (OTH) AF: 0.00 AC: 0 AN: 2114

Alfa AF: 0.00 Hom.: 19

Bravo AF: 0.000491

ExAC AF: 0.000157 AC: 19

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Uncertain:1 Benign:8

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Marfan syndrome Uncertain:1 Benign:1

Nov 01, 2016

Center for Human Genetics, Inc, Center for Human Genetics, Inc

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Feb 05, 2024

All of Us Research Program, National Institutes of Health

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

not specified Benign:2

Sep 14, 2016

GeneDx

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant is considered likely benign or benign based on one or more of the following criteria: it is a conservative change, it occurs at a poorly conserved position in the protein, it is predicted to be benign by multiple in silico algorithms, and/or has population frequency not consistent with disease.

Jun 26, 2023

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

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: FBN1 c.6832C>G (p.Pro2278Ala) results in a non-conservative amino acid change located in the EGF-like domain of the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 0.00011 in 251282 control chromosomes, predominantly at a frequency of 0.0017 within the African or African-American subpopulation in the gnomAD database. The observed variant frequency within African or African-American control individuals in the gnomAD database is approximately 15.11 fold of the estimated maximal expected allele frequency for a pathogenic variant in FBN1 causing Marfan Syndrome phenotype (0.00011), strongly suggesting that the variant is a benign polymorphism found primarily in populations of African or African-American origin. c.6832C>G has been reported in the literature in at least one individual affected with clinical features of FBN1-related conditions (Gillis_2017). However, this report does not provide unequivocal conclusions about association of the variant with FBN1-related conditions. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publication has been ascertained in the context of this evaluation (PMID: 28659821). Six submitters have cited clinical-significance assessments for this variant to ClinVar after 2014. Two submitters reported the variant as a variant of uncertain significance, while four reported it as likely benign. Based on the evidence outlined above, the variant was classified as likely benign.

Familial thoracic aortic aneurysm and aortic dissection Benign:2

Dec 14, 2018

Color Diagnostics, LLC DBA Color Health

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Jul 07, 2022

CHEO Genetics Diagnostic Laboratory, Children's Hospital of Eastern Ontario

Significance: Benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

not provided Benign:1

Apr 14, 2020

ARUP Laboratories, Molecular Genetics and Genomics, ARUP Laboratories

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

FBN1-related disorder Benign:1

Nov 10, 2022

PreventionGenetics, part of Exact Sciences

Significance: Likely benign

Review Status: no assertion criteria provided

Collection Method: clinical testing

This variant is classified as likely benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications).

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

Jan 27, 2025

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.084
BayesDel_addAF	Benign	-0.16	T
BayesDel_noAF	Uncertain	-0.010
CADD	Benign	23
DANN	Uncertain	0.99
Eigen	Uncertain	0.43
Eigen_PC	Uncertain	0.48
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Uncertain	0.87	D
M_CAP	Uncertain	0.20	D
MetaRNN	Benign	0.17	T
MetaSVM	Uncertain	0.51	D
PhyloP100		6.9
PrimateAI	Uncertain	0.51	T
PROVEAN	Pathogenic	-5.3	D
REVEL	Uncertain	0.56
Sift	Uncertain	0.015	D
Sift4G	Benign	0.094	T
Vest4		0.35
ClinPred		0.14	T
GERP RS		5.9
Mutation Taster		=33/67	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: rs363835; hg19: chr15-48722907;