rs184908092

Variant names:

• chr5-74721215-A-C
• rs184908092
• NM_032380.5:c.*440T>G

Variant summary

Our verdict is Benign. The variant received -12 ACMG points: 0P and 12B. BP4_Strong BS1 BS2

The NM_032380.5(GFM2):​c.*440T>G variant causes a 3 prime UTR change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000718 in 1,426,670 control chromosomes in the GnomAD database, including 6 homozygotes. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency:
  • Genomes: 𝑓 0.0036 (2 hom., cov: 32)
  • Exomes 𝑓: 0.00037 (4 hom.)
• Consequence: GFM2 NM_032380.5 3_prime_UTR
• Clinical Significance: Likely benign criteria provided, single submitter B:1
• Conservation: PhyloP100: 0.317
• Publications: 0 publications found

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]

HEXB Gene-Disease associations (from GenCC):

• Sandhoff disease

  Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P, ClinGen, Genomics England PanelApp, Myriad Women’s Health

ACMG classification

Our verdict: Benign. The variant received -12 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.82).
• BS1: Variant frequency is greater than expected in population afr. GnomAd4 allele frequency = 0.00363 (553/152314) while in subpopulation AFR AF = 0.0128 (534/41582). AF 95% confidence interval is 0.0119. There are 2 homozygotes in GnomAd4. There are 268 alleles in the male GnomAd4 subpopulation. Median coverage is 32. This position passed quality control check.
• BS2: High Homozygotes in GnomAd4 at 2 AR gene

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GFM2	NM_032380.5	c.*440T>G		3_prime_UTR_variant	Exon 21 of 21	ENST00000296805.8	NP_115756.2
HEXB	NM_000521.4	c.*40A>C		3_prime_UTR_variant	Exon 14 of 14	ENST00000261416.12	NP_000512.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GFM2	ENST00000296805.8	c.*440T>G		3_prime_UTR_variant	Exon 21 of 21	1	NM_032380.5	ENSP00000296805.3
HEXB	ENST00000261416.12	c.*40A>C		3_prime_UTR_variant	Exon 14 of 14	1	NM_000521.4	ENSP00000261416.7

Frequencies

GnomAD3 genomes AF: 0.00361 AC: 550 AN: 152196 Hom.: 2 Cov.: 32

Gnomad AFR AF: 0.0128

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.000917

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00

Gnomad SAS AF: 0.00

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00239

GnomAD2 exomes AF: 0.000938 AC: 234 AN: 249540 AF XY: 0.000754

Gnomad AFR exome AF: 0.0133

Gnomad AMR exome AF: 0.000667

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000165

GnomAD4 exome AF: 0.000370 AC: 472 AN: 1274356 Hom.: 4 Cov.: 18 AF XY: 0.000306 AC XY: 197 AN XY: 644318

African (AFR) AF: 0.0129 AC: 381 AN: 29612

American (AMR) AF: 0.000876 AC: 39 AN: 44510

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 24908

East Asian (EAS) AF: 0.00 AC: 0 AN: 38674

South Asian (SAS) AF: 0.0000121 AC: 1 AN: 82360

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53326

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5402

European-Non Finnish (NFE) AF: 0.00000850 AC: 8 AN: 941450

Other (OTH) AF: 0.000795 AC: 43 AN: 54114

GnomAD4 genome AF: 0.00363 AC: 553 AN: 152314 Hom.: 2 Cov.: 32 AF XY: 0.00360 AC XY: 268 AN XY: 74472

African (AFR) AF: 0.0128 AC: 534 AN: 41582

American (AMR) AF: 0.000915 AC: 14 AN: 15294

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3468

East Asian (EAS) AF: 0.00 AC: 0 AN: 5184

South Asian (SAS) AF: 0.00 AC: 0 AN: 4826

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10612

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 294

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68028

Other (OTH) AF: 0.00237 AC: 5 AN: 2114

Alfa AF: 0.00231 Hom.: 1

Bravo AF: 0.00399

Asia WGS AF: 0.000289 AC: 1 AN: 3474

ClinVar

Significance: Likely benign

Submissions summary: Benign:1

Revision: criteria provided, single submitter

Submissions by phenotype

Sandhoff disease Benign:1

Jan 13, 2018

Illumina Laboratory Services, Illumina

Significance: Likely benign

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant was observed in the ICSL laboratory as part of a predisposition screen in an ostensibly healthy population. It had not been previously curated by ICSL or reported in the Human Gene Mutation Database (HGMD: prior to June 1st, 2018), and was therefore a candidate for classification through an automated scoring system. Utilizing variant allele frequency, disease prevalence and penetrance estimates, and inheritance mode, an automated score was calculated to assess if this variant is too frequent to cause the disease. Based on the score and internal cut-off values, a variant classified as likely benign is not then subjected to further curation. The score for this variant resulted in a classification of likely benign for this disease. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.82
CADD	Benign	1.4
DANN	Benign	0.74
PhyloP100		0.32
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.0
Mutation Taster		=99/1	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: rs184908092; hg19: chr5-74017040;