rs1057519447

Variant names:

• chr6-98926570-A-G
• rs1057519447
• NM_001278716.2:c.419T>C

Variant summary

Our verdict is Pathogenic. The variant received 11 ACMG points: 11P and 0B. PM2 PP2 PP5_Very_Strong

The NM_001278716.2(FBXL4):​c.419T>C​(p.Val140Ala) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000372 in 1,614,046 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V140I) has been classified as Uncertain significance.

• Frequency:
  • Genomes: 𝑓 0.0000066 (0 hom., cov: 32)
  • Exomes 𝑓: 0.0000034 (0 hom.)
• Consequence: FBXL4 NM_001278716.2 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 8.87
• Publications: 4 publications found

Genes affected

FBXL4 (HGNC:13601): (F-box and leucine rich repeat protein 4) This gene encodes a member of the F-box protein family, which are characterized by an approximately 40 amino acid motif, the F-box. F-box proteins constitute one subunit of modular E3 ubiquitin ligase complexes, called SCF complexes, which function in phosphorylation-dependent ubiquitination. The F-box domain mediates protein-protein interactions and binds directly to S-phase kinase-associated protein 1. In addition to an F-box domain, the encoded protein contains at least 9 tandem leucine-rich repeats. The ubiquitin ligase complex containing the encoded protein may function in cell-cycle control by regulating levels of lysine-specific demethylase 4A. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jul 2013]

FBXL4 Gene-Disease associations (from GenCC):

• Leigh syndrome

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• mitochondrial DNA depletion syndrome 13

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: G2P, Labcorp Genetics (formerly Invitae), Genomics England PanelApp, Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 11 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 24 curated pathogenic missense variants (we use a threshold of 10). The gene has 1 curated benign missense variants. Gene score misZ: 0.55467 (below the threshold of 3.09). Trascript score misZ: 1.2845 (below the threshold of 3.09). GenCC associations: The gene is linked to Leigh syndrome, mitochondrial DNA depletion syndrome 13.
• PP5: Variant 6-98926570-A-G is Pathogenic according to our data. Variant chr6-98926570-A-G is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 375387.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FBXL4	NM_001278716.2	c.419T>C	p.Val140Ala	missense_variant	Exon 4 of 10	ENST00000369244.7	NP_001265645.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FBXL4	ENST00000369244.7	c.419T>C	p.Val140Ala	missense_variant	Exon 4 of 10	1	NM_001278716.2	ENSP00000358247.1
FBXL4	ENST00000229971.2	c.419T>C	p.Val140Ala	missense_variant	Exon 3 of 9	1		ENSP00000229971.1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152172 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.0000655

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: 0.0000119 AC: 3 AN: 251416 AF XY: 0.0000221

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000867

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: 0.00000342 AC: 5 AN: 1461874 Hom.: 0 Cov.: 31 AF XY: 0.00000688 AC XY: 5 AN XY: 727240

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.0000894 AC: 4 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

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

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53420

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

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111992

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152172 Hom.: 0 Cov.: 32 AF XY: 0.0000134 AC XY: 1 AN XY: 74352

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

African (AFR) AF: 0.00 AC: 0 AN: 41442

American (AMR) AF: 0.0000655 AC: 1 AN: 15278

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3470

East Asian (EAS) AF: 0.00 AC: 0 AN: 5192

South Asian (SAS) AF: 0.00 AC: 0 AN: 4832

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10610

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 316

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68032

Other (OTH) AF: 0.00 AC: 0 AN: 2088

⚠️ The allele balance in gnomAD version 4 Genomes is significantly skewed from the expected value of 0.5. (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Alfa AF: 0.00 Hom.: 0

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Mitochondrial DNA depletion syndrome 13 Pathogenic:4

Feb 26, 2025

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

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: FBXL4 c.419T>C (p.Val140Ala) results in a non-conservative amino acid change in the encoded protein sequence. Three of five in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 1.2e-05 in 251416 control chromosomes. c.419T>C has been reported in the literature in individuals affected with FBXL4-related mtDNA maintenance defect (Eldomery_2017, El-Hattab_2017). These data indicate that the variant is likely to be associated with disease. To our knowledge, no experimental evidence demonstrating an impact on protein function has been reported. The following publications have been ascertained in the context of this evaluation (PMID: 30804983, 36896912, 28940506, 28327206). ClinVar contains an entry for this variant (Variation ID: 375387). Based on the evidence outlined above, the variant was classified as likely pathogenic.. -

-

Lupski Lab, Baylor-Hopkins CMG, Baylor College of Medicine

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: research

This variant was identified in an individual with developmental delay, hypotonia, muscle weakness, autistic features, lactic acidosis. -

Aug 10, 2017

Wong Mito Lab, Molecular and Human Genetics, Baylor College of Medicine

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

The NM_012160.4:c.419T>C (NP_036292.2:p.Val140Ala) [GRCH38: NC_000006.12:g.98926570A>G] variant in FBXL4 gene is interpretated to be a Likely Pathogenic based on ACMG guidelines (PMID: 25741868). This variant meets one or more of the following evidence codes reported in the ACMG-guideline. PM2:This variant is absent in key population databases. PM3:Detected in trans with a pathogenic variant for Mitochondrial DNA depletion syndrome 13 which is a recessive disorder. PP2:This is a missense variant in FBXL4 with a low rate of benign and high rate of pathogenic missense variations. PP3:Computational evidence/predictors indicate the variant has deleterious effect on FBXL4 structure, function, or protein-protein interaction. PP4:Patient’s phenotype or family history is highly specific for FBXL4. Based on this evidence code ClinGen Pathogenicity Calculator (PMID:28081714) suggested that the variant is Likely Pathogenic. -

May 28, 2019

Mendelics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Pathogenic:2

Dec 25, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces valine, which is neutral and non-polar, with alanine, which is neutral and non-polar, at codon 140 of the FBXL4 protein (p.Val140Ala). This variant is present in population databases (no rsID available, gnomAD 0.009%). This missense change has been observed in individuals with clinical features of mitochondrial DNA depletion syndrome (PMID: 28327206, 28940506). ClinVar contains an entry for this variant (Variation ID: 375387). 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 FBXL4 protein function with a positive predictive value of 80%. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Nov 04, 2023

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Observed in homozygous or apparent homozygous state in patients with features of FBXL4-related mitochondrial DNA depletion syndrome in published literature and not observed in homozygous state in controls (PMID: 28940506, 28327206); Published functional studies demonstrate a damaging effect, including impaired substrate ubiquitination via disrupting SCF-FBXL4 assembly (PMID: 36896912); Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 30804983, 28327206, 28940506, 36896912) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.91
BayesDel_addAF	Benign	-0.16	T
BayesDel_noAF	Benign	-0.27
CADD	Uncertain	23
DANN	Uncertain	1.0
DEOGEN2	Benign	0.35	T;T
Eigen	Uncertain	0.50
Eigen_PC	Uncertain	0.57
FATHMM_MKL	Pathogenic	0.99	D
LIST_S2	Benign	0.85	.;D
M_CAP	Benign	0.021	T
MetaRNN	Uncertain	0.57	D;D
MetaSVM	Benign	-1.1	T
MutationAssessor	Uncertain	2.6	M;M
PhyloP100		8.9
PrimateAI	Uncertain	0.57	T
PROVEAN	Uncertain	-3.5	D;D
REVEL	Benign	0.26
Sift	Uncertain	0.0020	D;D
Sift4G	Uncertain	0.0080	D;D
Polyphen		0.61	P;P
Vest4		0.63
MutPred		0.35		Gain of loop (P = 0.0312);Gain of loop (P = 0.0312);
MVP		0.56
MPC		0.20
ClinPred		0.88	D
GERP RS		5.5
Varity_R		0.61
gMVP		0.77
Mutation Taster		=8/92	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.090		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: rs1057519447; hg19: chr6-99374446;