rs778048703

Positions:

• chr9-105604468-G-A
• chr9-105604468-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.623G>A​(p.Gly208Asp) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000547 in 1,461,806 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: 31)
  • Exomes 𝑓: 0.0000055 (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]

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, 0.909

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
FKTN	NM_001079802.2	c.623G>A	p.Gly208Asp	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.623G>A	p.Gly208Asp	missense_variant	6/11	5	NM_001079802.2	ENSP00000350687	P1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD3 exomes AF: 0.00000399 AC: 1 AN: 250656 Hom.: 0 AF XY: 0.00 AC XY: 0 AN XY: 135474

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

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: 0.00000885

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.00000547 AC: 8 AN: 1461806 Hom.: 0 Cov.: 32 AF XY: 0.00000413 AC XY: 3 AN XY: 727212

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: 0.00000719

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 31

Bravo AF: 0.00000378

ExAC AF: 0.00000824 AC: 1

EpiCase AF: 0.00

EpiControl AF: 0.0000593

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.	Apr 14, 2020	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Mar 19, 2022	This sequence change replaces glycine, which is neutral and non-polar, with aspartic acid, which is acidic and polar, at codon 208 of the FKTN protein (p.Gly208Asp). This variant is present in population databases (rs778048703, gnomAD 0.0009%). 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: 528816). Algorithms developed to predict the effect of missense changes on protein structure and function are either unavailable or do not agree on the potential impact of this missense change (SIFT: "Tolerated"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). 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 01, 2024

The c.623G>A (p.G208D) alteration is located in exon 6 (coding exon 4) of the FKTN gene. This alteration results from a G to A substitution at nucleotide position 623, causing the glycine (G) at amino acid position 208 to be replaced by an aspartic acid (D). 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	Pathogenic	0.93
BayesDel_addAF	Pathogenic	0.52	D
BayesDel_noAF	Pathogenic	0.50
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.68	D;D;.;.
Eigen	Pathogenic	0.83
Eigen_PC	Pathogenic	0.81
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Uncertain	0.92	.;D;.;D
M_CAP	Uncertain	0.28	D
MetaRNN	Pathogenic	0.91	D;D;D;D
MetaSVM	Pathogenic	1.0	D
MutationAssessor	Uncertain	2.5	M;M;M;M
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.71	T
PROVEAN	Uncertain	-3.1	.;D;.;D
REVEL	Pathogenic	0.93
Sift	Uncertain	0.0080	.;D;.;D
Sift4G	Uncertain	0.019	D;D;D;D
Polyphen		1.0	D;D;.;.
Vest4		0.86
MutPred		0.74		Loss of MoRF binding (P = 0.0705);Loss of MoRF binding (P = 0.0705);Loss of MoRF binding (P = 0.0705);Loss of MoRF binding (P = 0.0705);
MVP		0.92
MPC		0.44
ClinPred		0.96	D
GERP RS		5.4
Varity_R		0.57
gMVP		0.94

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: rs778048703; hg19: chr9-108366749;