5-74721776-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_032380.5(GFM2):c.2219C>T(p.Ser740Leu) 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. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: GFM2 NM_032380.5 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 9.60

Genes affected

GFM2 (HGNC:29682): (GTP dependent ribosome recycling factor mitochondrial 2) Eukaryotes contain two protein translational systems, one in the cytoplasm and one in the mitochondria. Mitochondrial translation is crucial for maintaining mitochondrial function and mutations in this system lead to a breakdown in the respiratory chain-oxidative phosphorylation system and to impaired maintenance of mitochondrial DNA. This gene encodes one of the mitochondrial translation elongation factors, which is a GTPase that plays a role at the termination of mitochondrial translation by mediating the disassembly of ribosomes from messenger RNA . Its role in the regulation of normal mitochondrial function and in disease states attributed to mitochondrial dysfunction is not known. Alternative splicing results in multiple transcript variants encoding distinct isoforms. [provided by RefSeq, Jul 2013]

HEXB (HGNC:4879): (hexosaminidase subunit beta) Hexosaminidase B is the beta subunit of the lysosomal enzyme beta-hexosaminidase that, together with the cofactor GM2 activator protein, catalyzes the degradation of the ganglioside GM2, and other molecules containing terminal N-acetyl hexosamines. Beta-hexosaminidase is composed of two subunits, alpha and beta, which are encoded by separate genes. Both beta-hexosaminidase alpha and beta subunits are members of family 20 of glycosyl hydrolases. Mutations in the alpha or beta subunit genes lead to an accumulation of GM2 ganglioside in neurons and neurodegenerative disorders termed the GM2 gangliosidoses. Beta subunit gene mutations lead to Sandhoff disease (GM2-gangliosidosis type II). Alternatively spliced transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, May 2014]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.896

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GFM2	NM_032380.5	c.2219C>T	p.Ser740Leu	missense_variant	21/21	ENST00000296805.8

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GFM2	ENST00000296805.8	c.2219C>T	p.Ser740Leu	missense_variant	21/21	1	NM_032380.5	P1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Data not reliable, filtered out with message: AS_VQSR AF: 6.86e-7 AC: 1 AN: 1456812 Hom.: 0 Cov.: 30 AF XY: 0.00000138 AC XY: 1 AN XY: 724532

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 9.00e-7

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not provided Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

GeneDx

Mar 13, 2023

Not observed at significant frequency in large population cohorts (gnomAD); In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; Has not been previously published as pathogenic or benign to our knowledge; In silico analysis is inconclusive as to whether the variant alters gene splicing. In the absence of RNA/functional studies, the actual effect of this sequence change is unknown. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.36
BayesDel_addAF	Pathogenic	0.38	D
BayesDel_noAF	Pathogenic	0.30
Cadd	Pathogenic	27
Dann	Pathogenic	1.0
DEOGEN2	Benign	0.030	T;.;T
Eigen	Pathogenic	0.89
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Pathogenic	1.0	D
M_CAP	Uncertain	0.21	D
MetaRNN	Pathogenic	0.90	D;D;D
MetaSVM	Uncertain	0.076	D
MutationAssessor	Uncertain	2.8	M;.;M
MutationTaster	Benign	1.0	D;D;D
PrimateAI	Uncertain	0.62	T
PROVEAN	Pathogenic	-4.8	D;D;D
REVEL	Pathogenic	0.67
Sift	Uncertain	0.0010	D;D;D
Sift4G	Uncertain	0.0030	D;D;D
Polyphen		1.0	D;D;D
Vest4		0.85
MutPred		0.66		Loss of catalytic residue at S740 (P = 0.0264);.;Loss of catalytic residue at S740 (P = 0.0264);
MVP		0.95
MPC		0.59
ClinPred		1.0	D
GERP RS		5.8
Varity_R		0.91
gMVP		0.90

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.29		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.29		Position offset: 7

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs969651735; hg19: chr5-74017601;