19-46755463-C-T

Variant names:

• chr19-46755463-C-T
• rs1060502108
• NM_024301.5:c.13C>T

Variant summary

Our verdict is Uncertain significance. The variant received 3 ACMG points: 3P and 0B. PM2 PP2

The NM_024301.5(FKRP):​c.13C>T​(p.Arg5Cys) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000687 in 1,454,862 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. R5R) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: FKRP NM_024301.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:2
• Conservation: PhyloP100: 0.831
• Publications: 1 publications found

Genes affected

FKRP (HGNC:17997): (fukutin related protein) This gene encodes a protein which is targeted to the medial Golgi apparatus and is necessary for posttranslational modification of dystroglycan. Mutations in this gene have been associated with congenital muscular dystrophy, cognitive disability, and cerebellar cysts. Several alternatively spliced transcript variants of this gene have been described, but the full-length nature of some of these variants has not been determined. [provided by RefSeq, Oct 2008]

FKRP Gene-Disease associations (from GenCC):

• autosomal recessive limb-girdle muscular dystrophy type 2I

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Laboratory for Molecular Medicine, Orphanet, Labcorp Genetics (formerly Invitae), Ambry Genetics
• muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A5

  Inheritance: AR Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Genomics England PanelApp, G2P, Ambry Genetics
• muscular dystrophy-dystroglycanopathy type B5

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Myriad Women’s Health, Labcorp Genetics (formerly Invitae)
• myopathy caused by variation in FKRP

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen
• congenital muscular dystrophy with cerebellar involvement

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet
• congenital muscular dystrophy with intellectual disability

  Inheritance: AR 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

ACMG classification

Our verdict: Uncertain_significance. The variant received 3 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 46 curated pathogenic missense variants (we use a threshold of 10). The gene has 2 curated benign missense variants. Gene score misZ: 1.8498 (below the threshold of 3.09). Trascript score misZ: -2.4986 (below the threshold of 3.09). GenCC associations: The gene is linked to autosomal recessive limb-girdle muscular dystrophy type 2I, muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A5, congenital muscular dystrophy with intellectual disability, muscular dystrophy-dystroglycanopathy, type A, muscle-eye-brain disease, congenital muscular dystrophy with cerebellar involvement, myopathy caused by variation in FKRP, muscular dystrophy-dystroglycanopathy type B5, congenital muscular dystrophy without intellectual disability.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
FKRP	NM_024301.5	c.13C>T	p.Arg5Cys	missense_variant	Exon 4 of 4	ENST00000318584.10	NP_077277.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
FKRP	ENST00000318584.10	c.13C>T	p.Arg5Cys	missense_variant	Exon 4 of 4	1	NM_024301.5	ENSP00000326570.4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.87e-7 AC: 1 AN: 1454862 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 723890

African (AFR) AF: 0.00 AC: 0 AN: 33416

American (AMR) AF: 0.00 AC: 0 AN: 44602

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26044

East Asian (EAS) AF: 0.00 AC: 0 AN: 39598

South Asian (SAS) AF: 0.00 AC: 0 AN: 85902

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 48098

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5756

European-Non Finnish (NFE) AF: 9.00e-7 AC: 1 AN: 1111264

Other (OTH) AF: 0.00 AC: 0 AN: 60182

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2

Revision: criteria provided, single submitter

Submissions by phenotype

Autosomal recessive limb-girdle muscular dystrophy type 2I Uncertain:1

Jan 13, 2021

Natera, Inc.

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Walker-Warburg congenital muscular dystrophy Uncertain:1

Nov 28, 2016

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine with cysteine at codon 5 of the FKRP protein (p.Arg5Cys). The arginine residue is moderately conserved and there is a large physicochemical difference between arginine and cysteine. This variant is not present in population databases (ExAC no frequency) and has not been reported in the literature in individuals with an FKRP-related disease. Algorithms developed to predict the effect of missense changes on protein structure and function do not agree on the potential impact of this missense change (SIFT: "Deleterious"; PolyPhen-2: "Possibly Damaging"; Align-GVGD: "Class C0"). In summary, this variant is a novel missense change with uncertain impact on protein function. It has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.23
BayesDel_addAF	Pathogenic	0.17	D
BayesDel_noAF	Uncertain	0.010
CADD	Benign	23
DANN	Uncertain	1.0
DEOGEN2	Benign	0.34	.;T;.;.;.;.;T;.;.;.;.;.;.;.;.;.;T
Eigen	Uncertain	0.33
Eigen_PC	Uncertain	0.35
FATHMM_MKL	Benign	0.72	D
LIST_S2	Uncertain	0.87	D;.;D;T;D;D;D;D;D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.65	D
MetaRNN	Uncertain	0.47	T;T;T;T;T;T;T;T;T;T;T;T;T;T;T;T;T
MetaSVM	Pathogenic	0.98	D
MutationAssessor	Benign	1.2	.;L;.;.;.;.;L;.;.;.;.;.;.;.;.;.;.
PhyloP100		0.83
PrimateAI	Uncertain	0.76	T
PROVEAN	Benign	-1.5	.;N;.;.;.;.;N;.;.;.;.;.;.;.;.;.;.
REVEL	Uncertain	0.51
Sift	Uncertain	0.021	.;D;.;.;.;.;D;.;.;.;.;.;.;.;.;.;.
Sift4G	Benign	0.080	T;T;D;D;D;D;T;D;D;D;D;D;D;D;D;D;D
Polyphen		1.0	.;D;.;.;.;.;D;.;.;.;.;.;.;.;.;.;.
Vest4		0.43, 0.48
MutPred		0.39		Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);Loss of MoRF binding (P = 0.0019);
MVP		0.98
MPC		1.6
ClinPred		0.90	D
GERP RS		4.9
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		2.6
Varity_R		0.11
gMVP		0.59
Mutation Taster		=77/23	polymorphism

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: rs1060502108; hg19: chr19-47258720;