Genetic Variant NM_033163.5:c.629delG (chr10-101770434-GC-G) – ACMG Classification: Likely_pathogenic (6 pts)

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PVS1_StrongPM2

The NM_033163.5(FGF8):c.629delG(p.Gly210AlafsTer109) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000686 in 1,456,974 control chromosomes in the GnomAD database, with no homozygous occurrence. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

Frequency

Genomes: not found (cov: 33)

Exomes 𝑓: 6.9e-7 ( 0 hom. )

Consequence

FGF8
NM_033163.5 frameshift

Scores

Not classified

Clinical Significance

Not reported in ClinVar

Conservation

PhyloP100: 7.45

Publications

0 publications found

Variant links:

Genes affected

FGF8 (HGNC:3686): (fibroblast growth factor 8) The protein encoded by this gene is a member of the fibroblast growth factor (FGF) family. FGF family members possess broad mitogenic and cell survival activities, and are involved in a variety of biological processes, including embryonic development, cell growth, morphogenesis, tissue repair, tumor growth and invasion. This protein is known to be a factor that supports androgen and anchorage independent growth of mammary tumor cells. Overexpression of this gene has been shown to increase tumor growth and angiogensis. The adult expression of this gene is restricted to testes and ovaries. Temporal and spatial pattern of this gene expression suggests its function as an embryonic epithelial factor. Studies of the mouse and chick homologs revealed roles in midbrain and limb development, organogenesis, embryo gastrulation and left-right axis determination. The alternative splicing of this gene results in four transcript variants. [provided by RefSeq, Jul 2008]

FGF8 Gene-Disease associations (from GenCC):

hypogonadotropic hypogonadism 6 with or without anosmia
Inheritance: AD Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics
hypogonadotropic hypogonadism
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
Kallmann syndrome
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
holoprosencephaly
Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

FGF8 links:

ENSG00000308881 (HGNC:):

ENSG00000308881 links:

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ACMG classification

Classification was made for transcript

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

PVS1

Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant is located in the 3'-most exon, not predicted to undergo nonsense mediated mRNA decay. Fraction of 0.144 CDS is truncated, and there are 1 pathogenic variants in the truncated region.

PM2

Very rare variant in population databases, with high coverage;

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FGF8	NM_033163.5 link	c.629delG	p.Gly210AlafsTer109	frameshift_variant	Exon 6 of 6	ENST00000320185.7	NP_149353.1	P55075-4A1A515

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FGF8	ENST00000320185.7 link	c.629delG	p.Gly210AlafsTer109	frameshift_variant	Exon 6 of 6	1	NM_033163.5	ENSP00000321797.2		P55075-4

Frequencies

GnomAD3 genomes

Cov.:

GnomAD4 exome

AF:

6.86e-7

AC:

AN:

1456974

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

724506

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33434

American (AMR)

AF:

0.00

AC:

AN:

43754

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25964

East Asian (EAS)

AF:

0.00

AC:

AN:

39524

South Asian (SAS)

AF:

0.0000117

AC:

AN:

85568

European-Finnish (FIN)

AF:

0.00

AC:

AN:

52788

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5728

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1110080

Other (OTH)

AF:

0.00

AC:

AN:

60134

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.225

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

Cov.:

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

7.4

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

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Computational scores

Splicing

Publications

Other links and lift over