chr5-70942362-A-C

Position:

• chr5-70942362-A-C

Variant summary

Our verdict is Uncertain significance. Variant got 2 ACMG points: 2P and 0B. PM1

The NM_000344.4(SMN1):​c.278A>C​(p.Lys93Thr) variant causes a missense change involving the alteration of a non-conserved nucleotide. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency: Genomes: not found (cov: 0)
• Consequence: SMN1 NM_000344.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.28

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 Uncertain_significance. Variant got 2 ACMG points.

• PM1: In a chain Survival motor neuron protein (size 292) in uniprot entity SMN_HUMAN there are 56 pathogenic changes around while only 0 benign (100%) in NM_000344.4

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
SMN1	NM_000344.4	c.278A>C	p.Lys93Thr	missense_variant	4/9	ENST00000380707.9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
SMN1	ENST00000380707.9	c.278A>C	p.Lys93Thr	missense_variant	4/9	1	NM_000344.4	P1

Frequencies

GnomAD3 genomes Cov.: 0

GnomAD4 exome Cov.: 0

GnomAD4 genome Cov.: 0

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Kugelberg-Welander disease Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Undiagnosed Diseases Network, NIH

Apr 03, 2019

This individual has been diagnosed with SMA based on phenotype and RNASeq data that suggests altered splicing and/or changes in expression levels. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.21
BayesDel_addAF	Uncertain	0.14	D
BayesDel_noAF	Uncertain	-0.040
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.70	.;D;.;D;D
Eigen	Benign	-0.098
Eigen_PC	Benign	-0.14
FATHMM_MKL	Uncertain	0.84	D
LIST_S2	Pathogenic	0.98	D;.;D;D;D
M_CAP	Pathogenic	0.50	D
MetaRNN	Uncertain	0.47	T;T;T;T;T
MetaSVM	Pathogenic	0.83	D
MutationTaster	Benign	0.95	D;D;D;D;D
PrimateAI	Benign	0.45	T
PROVEAN	Uncertain	-2.8	D;D;D;.;D
REVEL	Uncertain	0.55
Sift	Benign	0.14	T;T;T;.;T
Sift4G	Benign	0.15	T;T;T;T;T
Vest4		0.31
MutPred		0.55		Loss of methylation at K93 (P = 5e-04);Loss of methylation at K93 (P = 5e-04);Loss of methylation at K93 (P = 5e-04);Loss of methylation at K93 (P = 5e-04);Loss of methylation at K93 (P = 5e-04);
MVP		0.96
MPC		2.1
ClinPred		0.98	D
GERP RS		1.0
Varity_R		0.48
gMVP		0.41

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: rs1580886828; hg19: chr5-70238189;