rs778048703

Variant names:

• chr9-105604468-G-A
• rs778048703
• NM_001079802.2:c.623G>A

Your query was ambiguous. Multiple possible variants found:

• chr9-105604468-G-A
• chr9-105604468-G-T

Variant summary

Our verdict is Uncertain significance. The variant received 2 ACMG points: 2P and 0B. 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 (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G208V) has been classified 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
• Publications: 0 publications found

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 Gene-Disease associations (from GenCC):

• autosomal recessive limb-girdle muscular dystrophy type 2M

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), G2P
• muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A, 4

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), Orphanet, G2P
• myopathy caused by variation in FKTN

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• familial isolated dilated cardiomyopathy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
• congenital muscular dystrophy without intellectual disability

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• muscle-eye-brain disease

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• muscular dystrophy-dystroglycanopathy, type A

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• dilated cardiomyopathy 1X

  Inheritance: AR Classification: LIMITED Submitted by: Ambry Genetics

ACMG classification

Our verdict: Uncertain_significance. The variant received 2 ACMG points.

• PP3: MetaRNN computational evidence supports a deleterious effect, 0.909

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FKTN	NM_001079802.2	c.623G>A	p.Gly208Asp	missense_variant	Exon 6 of 11	ENST00000357998.10	NP_001073270.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FKTN	ENST00000357998.10	c.623G>A	p.Gly208Asp	missense_variant	Exon 6 of 11	5	NM_001079802.2	ENSP00000350687.6

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD2 exomes AF: 0.00000399 AC: 1 AN: 250656 AF XY: 0.00

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 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

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

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44720

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

East Asian (EAS) AF: 0.00 AC: 0 AN: 39696

South Asian (SAS) AF: 0.00 AC: 0 AN: 86254

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: 0.00000719 AC: 8 AN: 1111938

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

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000545418), which strongly suggests a high chance of mosaicism in these individuals.

GnomAD4 genome Cov.: 31

Alfa AF: 0.00 Hom.: 0

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

Apr 14, 2020

Natera, Inc.

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Nov 03, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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). Invitae Evidence Modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) indicates that this missense variant is expected to disrupt FKTN protein function with a positive predictive value of 95%. 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

May 01, 2024

Ambry Genetics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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
PhyloP100		8.4
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
Mutation Taster		=14/86	disease causing

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

Other links and lift over

dbSNP: rs778048703; hg19: chr9-108366749;