17-44915252-G-T

Variant names:

• chr17-44915252-G-T
• rs59793293
• NM_002055.5:c.235C>A

Variant summary

Our verdict is Likely pathogenic. Variant got 8 ACMG points: 8P and 0B. PM2 PM5 PP3_Strong

The NM_002055.5(GFAP):​c.235C>A​(p.Arg79Ser) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 12/21 in silico tools predict a damaging 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. R79L) has been classified as Pathogenic.

• Frequency: Genomes: not found (cov: 32)
• Consequence: GFAP NM_002055.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1 O:1
• Conservation: PhyloP100: 8.00

Genes affected

GFAP (HGNC:4235): (glial fibrillary acidic protein) This gene encodes one of the major intermediate filament proteins of mature astrocytes. It is used as a marker to distinguish astrocytes from other glial cells during development. Mutations in this gene cause Alexander disease, a rare disorder of astrocytes in the central nervous system. Alternative splicing results in multiple transcript variants encoding distinct isoforms. [provided by RefSeq, Oct 2008]

ACMG classification

Verdict is Likely_pathogenic. Variant got 8 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr17-44915251-C-A is described in Lovd as [Pathogenic].
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.986

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GFAP	NM_002055.5	c.235C>A	p.Arg79Ser	missense_variant	Exon 1 of 9	ENST00000588735.3	NP_002046.1
GFAP	NM_001363846.2	c.235C>A	p.Arg79Ser	missense_variant	Exon 1 of 10		NP_001350775.1
GFAP	NM_001242376.3	c.235C>A	p.Arg79Ser	missense_variant	Exon 1 of 7		NP_001229305.1
GFAP	NM_001131019.3	c.235C>A	p.Arg79Ser	missense_variant	Exon 1 of 8		NP_001124491.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GFAP	ENST00000588735.3	c.235C>A	p.Arg79Ser	missense_variant	Exon 1 of 9	1	NM_002055.5	ENSP00000466598.2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1 Other:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1 Other:1

-

Epithelial Biology; Institute of Medical Biology, Singapore

Significance: not provided

Review Status: no classification provided

Collection Method: literature only

- -

Aug 11, 2022

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

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. This variant disrupts the p.Arg79 amino acid residue in GFAP. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 11138011, 18584981, 23254569, 28882119). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be disruptive. ClinVar contains an entry for this variant (Variation ID: 66469). This missense change has been observed in individual(s) with Alexander disease (PMID: 21917775). This variant is not present in population databases (gnomAD no frequency). This sequence change replaces arginine, which is basic and polar, with serine, which is neutral and polar, at codon 79 of the GFAP protein (p.Arg79Ser). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.98
BayesDel_addAF	Pathogenic	0.52	D
BayesDel_noAF	Pathogenic	0.51
CADD	Pathogenic	32
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.96	.;D;.;.;.;D;.;.;.
Eigen	Pathogenic	0.77
Eigen_PC	Pathogenic	0.68
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.98	D;D;D;D;D;D;D;D;D
M_CAP	Pathogenic	0.64	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D;D;D;D
MetaSVM	Pathogenic	0.96	D
MutationAssessor	Pathogenic	4.2	.;H;.;H;H;.;.;.;.
PrimateAI	Pathogenic	0.85	D
PROVEAN	Pathogenic	-5.3	.;.;D;D;.;.;.;.;.
REVEL	Pathogenic	0.92
Sift	Pathogenic	0.0	.;.;D;D;.;.;.;.;.
Sift4G	Pathogenic	0.0010	.;.;D;D;.;D;D;.;.
Polyphen		0.99	.;D;.;.;.;.;.;.;.
Vest4		0.98, 0.99
MutPred		0.92		Loss of MoRF binding (P = 0.0266);Loss of MoRF binding (P = 0.0266);Loss of MoRF binding (P = 0.0266);Loss of MoRF binding (P = 0.0266);Loss of MoRF binding (P = 0.0266);Loss of MoRF binding (P = 0.0266);Loss of MoRF binding (P = 0.0266);Loss of MoRF binding (P = 0.0266);Loss of MoRF binding (P = 0.0266);
MVP		1.0
MPC		1.2
ClinPred		1.0	D
GERP RS		3.9
Varity_R		0.98
gMVP		0.98

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: rs59793293; hg19: chr17-42992620; COSMIC: COSV99493324; COSMIC: COSV99493324;