rs1555647265

Variant names:

• chr18-2750443-AC-A
• rs1555647265
• NM_015295.3:c.4104delC

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_015295.3(SMCHD1):​c.4104delC​(p.Val1369PhefsTer14) variant causes a frameshift change. The variant allele was found at a frequency of 0.000000685 in 1,459,334 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★). Variant results in nonsense mediated mRNA decay.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: SMCHD1 NM_015295.3 frameshift
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 5.43

Genes affected

SMCHD1 (HGNC:29090): (structural maintenance of chromosomes flexible hinge domain containing 1) This gene encodes a protein which contains a hinge region domain found in members of the SMC (structural maintenance of chromosomes) protein family. [provided by RefSeq, Dec 2011]

ENSG00000266049 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 18-2750443-AC-A is Pathogenic according to our data. Variant chr18-2750443-AC-A is described in ClinVar as [Pathogenic]. Clinvar id is 532807.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMCHD1	NM_015295.3	c.4104delC	p.Val1369PhefsTer14	frameshift_variant	Exon 32 of 48	ENST00000320876.11	NP_056110.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMCHD1	ENST00000320876.11	c.4104delC	p.Val1369PhefsTer14	frameshift_variant	Exon 32 of 48	5	NM_015295.3	ENSP00000326603.7

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.85e-7 AC: 1 AN: 1459334 Hom.: 0 Cov.: 31 AF XY: 0.00 AC XY: 0 AN XY: 725832

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: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Facioscapulohumeral muscular dystrophy 2 Pathogenic:1

Nov 28, 2017

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

While this particular variant has not been reported in the literature, loss of function variants in SMCHD1 are known to be pathogenic (PMID: 23143600). For these reasons, this variant has been classified as Pathogenic. This variant has not been reported in the literature in individuals with SMCHD1-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change creates a premature translational stop signal (p.Val1369Phefs*14) in the SMCHD1 gene. It is expected to result in an absent or disrupted protein product. -

Computational scores

Source: dbNSFP v4.3

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: rs1555647265; hg19: chr18-2750441;