19-46755685-G-C

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 4P and 2B. PM2 PM5 BP4_Moderate

The NM_024301.5(FKRP):c.235G>C(p.Val79Leu) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 12/21 in silico tools predict a benign 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. V79M) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: FKRP NM_024301.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 1.83

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 2 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr19-46755685-G-A is described in Lovd as [Pathogenic].
• BP4: Computational evidence support a benign effect (MetaRNN=0.21148461).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
FKRP	NM_024301.5	c.235G>C	p.Val79Leu	missense_variant	4/4	ENST00000318584.10

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
FKRP	ENST00000318584.10	c.235G>C	p.Val79Leu	missense_variant	4/4	1	NM_024301.5	P1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 33

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

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Aug 23, 2022

This sequence change replaces valine, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 79 of the FKRP protein (p.Val79Leu). 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: 1475218). Algorithms developed to predict the effect of missense changes on protein structure and function output the following: SIFT: "Tolerated"; PolyPhen-2: "Benign"; Align-GVGD: "Class C0". The leucine amino acid residue is found in multiple mammalian species, which suggests that this missense change does not adversely affect 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 v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.22
BayesDel_addAF	Uncertain	0.065	T
BayesDel_noAF	Benign	-0.14
Cadd	Benign	17
Dann	Benign	0.81
Eigen	Benign	-0.83
Eigen_PC	Benign	-0.69
FATHMM_MKL	Uncertain	0.82	D
LIST_S2	Benign	0.64	T;.;T;T;T;T;T;T;T;T
M_CAP	Uncertain	0.28	D
MetaRNN	Benign	0.21	T;T;T;T;T;T;T;T;T;T
MetaSVM	Pathogenic	0.98	D
MutationTaster	Benign	0.89	N;N
PrimateAI	Uncertain	0.64	T
Sift4G	Benign	0.29	T;T;T;T;T;T;T;T;T;T
Polyphen		0.030	.;B;.;B;.;.;.;.;.;.
Vest4		0.32, 0.32
MutPred		0.46		Loss of sheet (P = 0.1501);Loss of sheet (P = 0.1501);Loss of sheet (P = 0.1501);Loss of sheet (P = 0.1501);Loss of sheet (P = 0.1501);Loss of sheet (P = 0.1501);Loss of sheet (P = 0.1501);Loss of sheet (P = 0.1501);Loss of sheet (P = 0.1501);Loss of sheet (P = 0.1501);
MVP		0.54
MPC		0.65
ClinPred		0.12	T
GERP RS		2.6
Varity_R		0.16
gMVP		0.62

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr19-47258942;