5-70946157-A-G

Position:

• chr5-70946157-A-G

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PM1 PP3_Strong PP5_Very_Strong

The NM_000344.4(SMN1):​c.815A>G​(p.Tyr272Cys) variant causes a missense change involving the alteration of a conserved nucleotide. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 0)
  • Exomes 𝑓: 0.0 (0 hom.)
  • Failed GnomAD Quality Control
• Consequence: SMN1 NM_000344.4 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 8.49

Genes affected

SMN1 (HGNC:11117): (survival of motor neuron 1, telomeric) This gene is part of a 500 kb inverted duplication on chromosome 5q13. This duplicated region contains at least four genes and repetitive elements which make it prone to rearrangements and deletions. The repetitiveness and complexity of the sequence have also caused difficulty in determining the organization of this genomic region. The telomeric and centromeric copies of this gene are nearly identical and encode the same protein. However, mutations in this gene, the telomeric copy, are associated with spinal muscular atrophy; mutations in the centromeric copy do not lead to disease. The centromeric copy may be a modifier of disease caused by mutation in the telomeric copy. The critical sequence difference between the two genes is a single nucleotide in exon 7, which is thought to be an exon splice enhancer. Note that the nine exons of both the telomeric and centromeric copies are designated historically as exon 1, 2a, 2b, and 3-8. It is thought that gene conversion events may involve the two genes, leading to varying copy numbers of each gene. The protein encoded by this gene localizes to both the cytoplasm and the nucleus. Within the nucleus, the protein localizes to subnuclear bodies called gems which are found near coiled bodies containing high concentrations of small ribonucleoproteins (snRNPs). This protein forms heteromeric complexes with proteins such as SIP1 and GEMIN4, and also interacts with several proteins known to be involved in the biogenesis of snRNPs, such as hnRNP U protein and the small nucleolar RNA binding protein. Multiple transcript variants encoding distinct isoforms have been described. [provided by RefSeq, Jul 2014]

ACMG classification

Verdict is Pathogenic. Variant got 14 ACMG points.

• PM1: In a hotspot region, there are 8 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 3 uncertain in NM_000344.4
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.993
• PP5: Variant 5-70946157-A-G is Pathogenic according to our data. Variant chr5-70946157-A-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 9166.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr5-70946157-A-G is described in UniProt as null. Variant chr5-70946157-A-G is described in UniProt as null. Variant chr5-70946157-A-G is described in UniProt as null. Variant chr5-70946157-A-G is described in UniProt as null. Variant chr5-70946157-A-G is described in UniProt as null. Variant chr5-70946157-A-G is described in UniProt as null. Variant chr5-70946157-A-G is described in UniProt as null. Variant chr5-70946157-A-G is described in UniProt as null. Variant chr5-70946157-A-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SMN1	NM_000344.4	c.815A>G	p.Tyr272Cys	missense_variant	7/9	ENST00000380707.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SMN1	ENST00000380707.9	c.815A>G	p.Tyr272Cys	missense_variant	7/9	1	NM_000344.4	P1

Frequencies

GnomAD3 genomes Cov.: 0

GnomAD4 exome Data not reliable, filtered out with message: AC0;AS_VQSR AF: 0.00 AC: 0 AN: 5714 Hom.: 0 Cov.: 0 AF XY: 0.00 AC XY: 0 AN XY: 2992

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 0

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Werdnig-Hoffmann disease Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	Molecular Diagnostics Lab, Nemours Children's Health, Delaware	Mar 01, 2016	- -
Pathogenic, no assertion criteria provided	literature only	OMIM	Jan 13, 1995	- -

Spinal muscular atrophy Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Victorian Clinical Genetics Services, Murdoch Childrens Research Institute

Feb 02, 2022

Based on the classification scheme VCGS_Germline_v1.3.4, this variant is classified as Pathogenic. Following criteria are met: 0102 - Loss of function is a known mechanism of disease in this gene and is associated with spinal muscular atrophy. (I) 0106 - This gene is associated with autosomal recessive disease. (I) 0200 - Variant is predicted to result in a missense amino acid change from tyrosine to cysteine. (I) 0251 - This variant is heterozygous. (I) 0501 - Missense variant is highly conserved with a major amino acid change. (SP) 0604 - Variant is not located in an established domain, motif, hotspot or informative constraint region. (I) 0801 - This variant has strong previous evidence of pathogenicity in unrelated individuals. This is one of the most common pathogenic variants reported in patients with spinal muscular atrophy (PMID: 7813012, 10205265, 10679938, 31301241). (SP) 1208 - Inheritance information for this variant is not currently available. (I) Legend: (SP) - Supporting pathogenic, (I) - Information, (SB) - Supporting benign -

not provided Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Athena Diagnostics

Jun 01, 2023

Frequency data for this variant in the general population cannot be distinguished from that of the SMN2 gene, and is therefore uninformative in assessment of variant pathogenicity (Genome Aggregation Database (gnomAD), Cambridge, MA (URL: http://gnomad.broadinstitute.org)). This variant has been identified in multiple unrelated individuals with clinical features associated with this gene. Assessment of experimental evidence suggests this variant results in abnormal protein function. Studies show this variant causes reduced self-oligomerization, and reduced binding to Sm proteins (PMID: 9590291, 10500148). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.58	D
BayesDel_noAF	Pathogenic	0.60
CADD	Pathogenic	31
DANN	Uncertain	0.98
DEOGEN2	Pathogenic	0.90	.;D;D;.;D;D
Eigen	Uncertain	0.31
Eigen_PC	Uncertain	0.32
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Pathogenic	0.98	D;.;D;D;D;D
M_CAP	Pathogenic	0.90	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationTaster	Benign	1.0	A;A;A;A;A
PrimateAI	Pathogenic	0.87	D
PROVEAN	Pathogenic	-7.4	D;D;D;D;.;.
REVEL	Pathogenic	0.98
Sift	Pathogenic	0.0	D;D;D;D;.;.
Sift4G	Pathogenic	0.0010	D;D;D;D;D;D
Vest4		0.91
MutPred		0.97		.;Gain of helix (P = 0.132);.;Gain of helix (P = 0.132);Gain of helix (P = 0.132);Gain of helix (P = 0.132);
MVP		1.0
MPC		2.1
ClinPred		1.0	D
GERP RS		3.4
Varity_R		0.94
gMVP		0.96

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: rs104893922; hg19: chr5-70241984;