chr19-46755455-G-T

Variant names:

• chr19-46755455-G-T
• rs1308459613
• NM_024301.5:c.5G>T

Variant summary

Our verdict is Uncertain significance. The variant received 5 ACMG points: 5P and 0B. PM2 PP2 PP3_Moderate

The NM_024301.5(FKRP):​c.5G>T​(p.Arg2Leu) variant causes a missense change. The variant allele was found at a frequency of 0.000000688 in 1,453,230 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. R2W) has been classified as Uncertain significance.

• 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:1
• Conservation: PhyloP100: 6.13
• Publications: 2 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 5 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.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.887

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_024301.5. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	FKRP	NM_024301.5	MANE Select	c.5G>T	p.Arg2Leu	missense	Exon 4 of 4	NP_077277.1
	FKRP	NM_001039885.3		c.5G>T	p.Arg2Leu	missense	Exon 4 of 4	NP_001034974.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	FKRP	ENST00000318584.10	TSL:1 MANE Select	c.5G>T	p.Arg2Leu	missense	Exon 4 of 4	ENSP00000326570.4
	FKRP	ENST00000391909.7	TSL:2	c.5G>T	p.Arg2Leu	missense	Exon 4 of 4	ENSP00000375776.2
	FKRP	ENST00000601299.5	TSL:4	c.5G>T	p.Arg2Leu	missense	Exon 3 of 3	ENSP00000470103.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome AF: 6.88e-7 AC: 1 AN: 1453230 Hom.: 0 Cov.: 32 AF XY: 0.00 AC XY: 0 AN XY: 723054

African (AFR) AF: 0.0000299 AC: 1 AN: 33408

American (AMR) AF: 0.00 AC: 0 AN: 44552

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26018

East Asian (EAS) AF: 0.00 AC: 0 AN: 39592

South Asian (SAS) AF: 0.00 AC: 0 AN: 85846

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 46756

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5744

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1111144

Other (OTH) AF: 0.00 AC: 0 AN: 60170

GnomAD4 genome Cov.: 33

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Walker-Warburg congenital muscular dystrophy Uncertain:1

Dec 06, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces arginine, which is basic and polar, with leucine, which is neutral and non-polar, at codon 2 of the FKRP protein (p.Arg2Leu). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with FKRP-related conditions. ClinVar contains an entry for this variant (Variation ID: 459240). 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) has been performed for this missense variant. However, the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on FKRP 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.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.27
BayesDel_addAF	Pathogenic	0.39	D
BayesDel_noAF	Pathogenic	0.32
CADD	Pathogenic	26
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.71	D
Eigen	Uncertain	0.54
Eigen_PC	Uncertain	0.50
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Benign	0.85	T
M_CAP	Pathogenic	0.82	D
MetaRNN	Pathogenic	0.89	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Benign	1.7	L
PhyloP100		6.1
PrimateAI	Pathogenic	0.86	D
PROVEAN	Uncertain	-3.8	D
REVEL	Pathogenic	0.83
Sift	Uncertain	0.0050	D
Sift4G	Pathogenic	0.0	D
Polyphen		1.0	D
Vest4		0.75
MutPred		0.45		Loss of MoRF binding (P = 0.0071)
MVP		0.98
MPC		1.8
ClinPred		0.98	D
GERP RS		3.9
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.0
Varity_R		0.43
gMVP		0.63
Mutation Taster		=7/93	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: rs1308459613; hg19: chr19-47258712;