9-105604431-G-T

Position:

• chr9-105604431-G-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_001079802.2(FKTN):​c.586G>T​(p.Asp196Tyr) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,461,714 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: 0.0000027 (0 hom.)
• Consequence: FKTN NM_001079802.2 missense
• Clinical Significance: Uncertain significance criteria provided, multiple submitters, no conflicts U:3
• Conservation: PhyloP100: 8.44

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]

FKTN (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.925

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
FKTN	NM_001079802.2	c.586G>T	p.Asp196Tyr	missense_variant	6/11	ENST00000357998.10	NP_001073270.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
FKTN	ENST00000357998.10	c.586G>T	p.Asp196Tyr	missense_variant	6/11	5	NM_001079802.2	ENSP00000350687.6

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD3 exomes AF: 0.0000119 AC: 3 AN: 251054 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135678

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.0000868

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS 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: 0.00000274 AC: 4 AN: 1461714 Hom.: 0 Cov.: 32 AF XY: 0.00000275 AC XY: 2 AN XY: 727186

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.0000671

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: 8.99e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Walker-Warburg congenital muscular dystrophy Uncertain:2

Uncertain significance, no assertion criteria provided	clinical testing	Natera, Inc.	Oct 28, 2019	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Oct 13, 2022	This sequence change replaces aspartic acid, which is acidic and polar, with tyrosine, which is neutral and polar, at codon 196 of the FKTN protein (p.Asp196Tyr). This variant is present in population databases (rs756748012, gnomAD 0.009%). This variant has not been reported in the literature in individuals affected with FKTN-related conditions. ClinVar contains an entry for this variant (Variation ID: 407110). 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 FKTN protein function. 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. -

Cardiovascular phenotype Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

May 16, 2024

The c.586G>T (p.D196Y) alteration is located in exon 6 (coding exon 4) of the FKTN gene. This alteration results from a G to T substitution at nucleotide position 586, causing the aspartic acid (D) at amino acid position 196 to be replaced by a tyrosine (Y). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.29
BayesDel_addAF	Pathogenic	0.34	D
BayesDel_noAF	Pathogenic	0.45
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.64	D;D;.;.
Eigen	Pathogenic	0.81
Eigen_PC	Pathogenic	0.79
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.93	.;D;.;D
M_CAP	Uncertain	0.17	D
MetaRNN	Pathogenic	0.92	D;D;D;D
MetaSVM	Pathogenic	0.90	D
MutationAssessor	Uncertain	2.3	M;M;M;M
PrimateAI	Uncertain	0.60	T
PROVEAN	Uncertain	-2.7	.;D;.;N
REVEL	Pathogenic	0.93
Sift	Uncertain	0.0030	.;D;.;D
Sift4G	Uncertain	0.0060	D;D;D;D
Polyphen		1.0	D;D;.;.
Vest4		0.97
MutPred		0.74		Loss of loop (P = 0.0288);Loss of loop (P = 0.0288);Loss of loop (P = 0.0288);Loss of loop (P = 0.0288);
MVP		0.91
MPC		0.48
ClinPred		0.97	D
GERP RS		5.4
Varity_R		0.57
gMVP		0.89

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: rs756748012; hg19: chr9-108366712;