Genetic Variant FBN1:p.Pro2278Ala (chr15-48430710-G-C) – ACMG Classification: Likely_benign (-4 pts)

Variant summary

Our verdict is Likely benign. The variant received -4 ACMG points: 3P and 7B. PM1PP2BP4_ModerateBP6BS1

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. The gene FBN1 is included in the ClinGen Criteria Specification Registry.

Frequency

Genomes: 𝑓 0.00049 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000054 ( 0 hom. )

Consequence

FBN1
NM_000138.5 missense

Scores

Clinical Significance

Conflicting classifications of pathogenicity criteria provided, conflicting classifications U:1B:8

Conservation

PhyloP100: 6.88

Publications

12 publications found

Variant links:

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):

Marfan syndrome
Inheritance: AD, AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), G2P, ClinGen, Orphanet, Genomics England PanelApp
familial thoracic aortic aneurysm and aortic dissection
Inheritance: Unknown, AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: ClinGen, Orphanet
Acromicric dysplasia
Inheritance: AD Classification: STRONG, SUPPORTIVE Submitted by: Ambry Genetics, Orphanet
progeroid and marfanoid aspect-lipodystrophy syndrome
Inheritance: AD Classification: STRONG, MODERATE, SUPPORTIVE Submitted by: Ambry Genetics, Orphanet, Labcorp Genetics (formerly Invitae)
stiff skin syndrome
Inheritance: AD Classification: STRONG, LIMITED Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics
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: Unknown, AD Classification: LIMITED, NO_KNOWN Submitted by: Labcorp Genetics (formerly Invitae), ClinGen

FBN1 links:

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ACMG classification

Specifications for FBN1 are available in the ClinGen Criteria Specification Registry and recommended for reference when assigning criteria.

Classification was made for transcript

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 Weill-Marchesani syndrome 2, dominant, Acromicric dysplasia, isolated ectopia lentis, progeroid and marfanoid aspect-lipodystrophy syndrome, Marfan syndrome, stiff skin syndrome, Shprintzen-Goldberg syndrome, familial thoracic aortic aneurysm and aortic dissection, ectopia lentis 1, isolated, autosomal dominant, Weill-Marchesani syndrome, neonatal Marfan syndrome, geleophysic dysplasia.

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.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000138.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	FBN1	NM_000138.5	MANE Select	c.6832C>G	p.Pro2278Ala	missense	Exon 56 of 66	NP_000129.3
	FBN1	NM_001406716.1		c.6832C>G	p.Pro2278Ala	missense	Exon 55 of 65	NP_001393645.1	P35555

Ensembl Transcripts

Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
FBN1	ENST00000316623.10	TSL:1 MANE Select	c.6832C>G	p.Pro2278Ala	missense	Exon 56 of 66	ENSP00000325527.5	P35555
FBN1	ENST00000559133.6	TSL:1	n.6832C>G		non_coding_transcript_exon	Exon 56 of 67	ENSP00000453958.2	H0YND0
FBN1	ENST00000674301.2		n.*283C>G		non_coding_transcript_exon	Exon 57 of 68	ENSP00000501333.2	A0A6I8PL22

Frequencies

GnomAD3 genomes

AF:

0.000486

AC:

AN:

152110

Hom.:

Cov.:

show subpopulations

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:

AN:

251282

AF XY:

0.0000663

show subpopulations

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:

AN:

1461602

Hom.:

Cov.:

AF XY:

0.0000481

AC XY:

AN XY:

727122

show subpopulations

African (AFR)

AF:

0.00212

AC:

AN:

33458

American (AMR)

AF:

0.00

AC:

AN:

44714

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26122

East Asian (EAS)

AF:

0.00

AC:

AN:

39690

South Asian (SAS)

AF:

0.00

AC:

AN:

86258

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53404

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5768

European-Non Finnish (NFE)

AF:

8.99e-7

AC:

AN:

1111818

Other (OTH)

AF:

0.000116

AC:

AN:

60370

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.473

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.000486

AC:

AN:

152228

Hom.:

Cov.:

AF XY:

0.000390

AC XY:

AN XY:

74420

show subpopulations

African (AFR)

AF:

0.00178

AC:

AN:

41518

American (AMR)

AF:

0.00

AC:

AN:

15284

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5184

South Asian (SAS)

AF:

0.00

AC:

AN:

4824

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10606

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68024

Other (OTH)

AF:

0.00

AC:

AN:

2114

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.492

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.000491

ExAC

AF:

0.000157

AC:

ClinVar

ClinVar submissions

Significance:Conflicting classifications of pathogenicity

Revision:criteria provided, conflicting classifications

View on ClinVar

Pathogenic

VUS

Benign

Condition

Familial thoracic aortic aneurysm and aortic dissection (2)

Marfan syndrome (2)

not specified (2)

FBN1-related disorder (1)

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

not provided (1)

Computational scores

Source: dbNSFP v4.9

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.084

BayesDel_addAF

Benign

-0.16

BayesDel_noAF

Uncertain

-0.010

CADD

Benign

(source)

DANN

Uncertain

0.99

Eigen

Uncertain

0.43

Eigen_PC

Uncertain

0.48

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.87

M_CAP

Uncertain

0.20

MetaRNN

Benign

0.17

MetaSVM

Uncertain

0.51

PhyloP100

6.9

PrimateAI

Uncertain

0.51

PROVEAN

Pathogenic

-5.3

REVEL

Uncertain

0.56

Sift

Uncertain

0.015

Sift4G

Benign

0.094

Vest4

0.35

MVP

0.69

MPC

1.4

ClinPred

0.14

GERP RS

5.9

Mutation Taster

=33/67

disease causing

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Variant Effect in Transcripts

RefSeq Transcripts

Ensembl Transcripts

Frequencies

Age Distribution

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over