18-2750450-C-G

Variant names:

Variant summary

Our verdict is Likely benign. The variant received -1 ACMG points: 0P and 1B. BP4

The NM_015295.3(SMCHD1):c.4108C>G(p.Arg1370Gly) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000372 in 1,610,854 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R1370C) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000020 ( 0 hom., cov: 32)

Exomes 𝑓: 0.0000021 ( 0 hom. )

Consequence

SMCHD1
NM_015295.3 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:1

Conservation

PhyloP100: 0.580

Publications

5 publications found

Variant links:

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]

SMCHD1 Gene-Disease associations (from GenCC):

arhinia, choanal atresia, and microphthalmia
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), PanelApp Australia, G2P, Ambry Genetics, ClinGen, Illumina
facioscapulohumeral muscular dystrophy
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
hyposmia-nasal and ocular hypoplasia-hypogonadotropic hypogonadism syndrome
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

SMCHD1 links:

ENSG00000266049 (HGNC:):

ENSG00000266049 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Likely_benign. The variant received -1 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.27875084).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMCHD1	NM_015295.3 link	c.4108C>G	p.Arg1370Gly	missense_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 link	c.4108C>G	p.Arg1370Gly	missense_variant	Exon 32 of 48	5	NM_015295.3	ENSP00000326603.7		A6NHR9-1

Frequencies

GnomAD3 genomes

AF:

0.0000197

AC:

AN:

152058

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000197

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:

0.00

GnomAD4 exome

AF:

0.00000206

AC:

AN:

1458796

Hom.:

Cov.:

AF XY:

0.00000138

AC XY:

AN XY:

725514

show subpopulations

⚠️ The allele balance in gnomAD version 4 Exomes is significantly skewed from the expected value of 0.5.

African (AFR)

AF:

0.00

AC:

AN:

33420

American (AMR)

AF:

0.0000678

AC:

AN:

44274

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

25986

East Asian (EAS)

AF:

0.00

AC:

AN:

39584

South Asian (SAS)

AF:

0.00

AC:

AN:

85902

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53300

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5754

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1110300

Other (OTH)

AF:

0.00

AC:

AN:

60276

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.0338994), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.392

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000197

AC:

AN:

152058

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74250

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41432

American (AMR)

AF:

0.000197

AC:

AN:

15252

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3470

East Asian (EAS)

AF:

0.00

AC:

AN:

5202

South Asian (SAS)

AF:

0.00

AC:

AN:

4826

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10592

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

67972

Other (OTH)

AF:

0.00

AC:

AN:

2086

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.0000113

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Facioscapulohumeral muscular dystrophy 2

Uncertain:1

May 29, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Uncertain significance

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change replaces arginine, which is basic and polar, with glycine, which is neutral and non-polar, at codon 1370 of the SMCHD1 protein (p.Arg1370Gly). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with SMCHD1-related conditions. ClinVar contains an entry for this variant (Variation ID: 532806). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is not expected to disrupt SMCHD1 protein function with a negative predictive value of 80%. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.14

BayesDel_addAF

Benign

-0.079

BayesDel_noAF

Benign

-0.35

CADD

Benign

(source)

DANN

Uncertain

1.0

DEOGEN2

Benign

0.36

Eigen

Uncertain

0.38

Eigen_PC

Uncertain

0.40

FATHMM_MKL

Uncertain

0.77

LIST_S2

Benign

0.84

M_CAP

Benign

0.027

MetaRNN

Benign

0.28

MetaSVM

Benign

-0.92

MutationAssessor

Uncertain

2.1

PhyloP100

0.58

PrimateAI

Benign

0.29

PROVEAN

Benign

-2.0

REVEL

Benign

0.11

Sift

Benign

0.047

Sift4G

Benign

0.25

Polyphen

0.96

Vest4

0.37

MutPred

0.40

Loss of sheet (P = 0.007);

MVP

0.20

MPC

0.43

ClinPred

0.71

GERP RS

5.0

Varity_R

0.13

gMVP

0.65

Mutation Taster

=74/26

polymorphism

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over