chr9-105575090-T-G

Position:

• chr9-105575090-T-G

Variant summary

Our verdict is Likely pathogenic. Variant got 6 ACMG points: 6P and 0B. PM1 PM2 PP3_Moderate

The NM_001079802.2(FKTN):​c.58T>G​(p.Phe20Val) variant causes a missense change. The variant allele was found at a frequency of 0.00000206 in 1,459,784 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000021 (0 hom.)
• Consequence: FKTN NM_001079802.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:5
• Conservation: PhyloP100: 5.34

Genes affected

FKTN (HGNC:3622): (fukutin) The protein encoded by this gene is a putative transmembrane protein that is localized to the cis-Golgi compartment, where it may be involved in the glycosylation of alpha-dystroglycan in skeletal muscle. The encoded protein is thought to be a glycosyltransferase and could play a role in brain development. Defects in this gene are a cause of Fukuyama-type congenital muscular dystrophy (FCMD), Walker-Warburg syndrome (WWS), limb-girdle muscular dystrophy type 2M (LGMD2M), and dilated cardiomyopathy type 1X (CMD1X). Alternatively spliced transcript variants have been found for this gene. [provided by RefSeq, Nov 2010]

ACMG classification

Verdict is Likely_pathogenic. Variant got 6 ACMG points.

• PM1: In a transmembrane_region Helical; Signal-anchor for type II membrane protein (size 20) in uniprot entity FKTN_HUMAN there are 4 pathogenic changes around while only 0 benign (100%) in NM_001079802.2
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.844

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
FKTN	NM_001079802.2	c.58T>G	p.Phe20Val	missense_variant	3/11	ENST00000357998.10	NP_001073270.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
FKTN	ENST00000357998.10	c.58T>G	p.Phe20Val	missense_variant	3/11	5	NM_001079802.2	ENSP00000350687	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000206 AC: 3 AN: 1459784 Hom.: 0 Cov.: 28 AF XY: 0.00000275 AC XY: 2 AN XY: 726370

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 32

Alfa AF: 0.0000370 Hom.: 0

Bravo AF: 0.00000378

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:5

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Uncertain:3

Uncertain significance, criteria provided, single submitter	clinical testing	Revvity Omics, Revvity	Oct 01, 2019	- -
Uncertain significance, criteria provided, single submitter	clinical testing	GeneDx	Apr 06, 2021	Not observed in large population cohorts (Lek et al., 2016); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge -
Uncertain significance, criteria provided, single submitter	clinical testing	Eurofins Ntd Llc (ga)	Dec 05, 2017	- -

Cardiovascular phenotype Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Mar 16, 2024

The p.F20V variant (also known as c.58T>G), located in coding exon 1 of the FKTN gene, results from a T to G substitution at nucleotide position 58. The phenylalanine at codon 20 is replaced by valine, an amino acid with highly similar properties. This amino acid position is conserved. In addition, this alteration is predicted to be deleterious by in silico analysis. Based on the available evidence, the clinical significance of this alteration remains unclear. -

Walker-Warburg congenital muscular dystrophy Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 03, 2021

This sequence change replaces phenylalanine with valine at codon 20 of the FKTN protein (p.Phe20Val). The phenylalanine residue is highly conserved and there is a small physicochemical difference between phenylalanine and valine. This variant is not present in population databases (ExAC no frequency). This missense change has been observed in individual(s) with LBBB, PVC, atrial fibrillation, nonischemic cardiomyopathy (Invitae). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.36
BayesDel_addAF	Pathogenic	0.41	D
BayesDel_noAF	Pathogenic	0.35
CADD	Pathogenic	27
DANN	Uncertain	0.99
DEOGEN2	Benign	0.30	T;T;.;.
Eigen	Uncertain	0.66
Eigen_PC	Uncertain	0.63
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Uncertain	0.92	.;D;.;D
M_CAP	Pathogenic	0.34	D
MetaRNN	Pathogenic	0.84	D;D;D;D
MetaSVM	Pathogenic	0.87	D
MutationAssessor	Uncertain	2.3	M;M;M;M
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.66	T
PROVEAN	Benign	-1.7	.;N;D;N
REVEL	Pathogenic	0.82
Sift	Uncertain	0.0060	.;D;D;D
Sift4G	Uncertain	0.034	D;D;D;D
Polyphen		1.0	D;D;.;.
Vest4		0.79
MutPred		0.55		Loss of stability (P = 0.0567);Loss of stability (P = 0.0567);Loss of stability (P = 0.0567);Loss of stability (P = 0.0567);
MVP		0.88
MPC		0.52
ClinPred		0.96	D
GERP RS		5.2
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.41
gMVP		0.65

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: rs1554731003; hg19: chr9-108337371;