dbSNP rs142973168: SMCHD1:c.2604-7delT (chr18-2724884-AT-A) – ACMG Classification: Benign (-8 pts)

Variant summary

Our verdict is Benign. The variant received -8 ACMG points: 0P and 8B. BP6_Very_Strong

The NM_015295.3(SMCHD1):c.2604-7delT variant causes a splice region, intron change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000539 in 1,501,652 control chromosomes in the GnomAD database, with no homozygous occurrence. There is a variant allele frequency bias in the population database for this variant (GnomAdExome4), which may indicate mosaicism or somatic mutations in the reference population data. 1/1 splice prediction tools predict no significant impact on normal splicing. Variant has been reported in ClinVar as Likely benign (★★).

Frequency

Genomes: 𝑓 0.000026 ( 0 hom., cov: 30)

Exomes 𝑓: 0.000057 ( 0 hom. )

Consequence

SMCHD1
NM_015295.3 splice_region, intron

Scores

Not classified

Clinical Significance

Benign/Likely benign criteria provided, multiple submitters, no conflicts B:2

Conservation

PhyloP100: -0.239

Publications

1 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: Benign. The variant received -8 ACMG points.

BP6

Variant 18-2724884-AT-A is Benign according to our data. Variant chr18-2724884-AT-A is described in ClinVar as Benign/Likely_benign. ClinVar VariationId is 260639.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
SMCHD1	NM_015295.3 link	c.2604-7delT		splice_region_variant, intron_variant	Intron 20 of 47	ENST00000320876.11	NP_056110.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
SMCHD1	ENST00000320876.11 link	c.2604-14delT		intron_variant	Intron 20 of 47	5	NM_015295.3	ENSP00000326603.7		A6NHR9-1

Frequencies

GnomAD3 genomes

AF:

0.0000263

AC:

AN:

151962

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

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:

0.0000589

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.000139

AC:

AN:

165486

AF XY:

0.000170

show subpopulations

Gnomad AFR exome

AF:

0.000100

Gnomad AMR exome

AF:

0.0000414

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.000162

Gnomad OTH exome

AF:

0.000224

GnomAD4 exome

AF:

0.0000571

AC:

AN:

1349690

Hom.:

Cov.:

AF XY:

0.0000674

AC XY:

AN XY:

668108

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:

31622

American (AMR)

AF:

0.0000552

AC:

AN:

36226

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

24088

East Asian (EAS)

AF:

0.00

AC:

AN:

37064

South Asian (SAS)

AF:

0.000203

AC:

AN:

74050

European-Finnish (FIN)

AF:

0.0000426

AC:

AN:

46934

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5492

European-Non Finnish (NFE)

AF:

0.0000530

AC:

AN:

1038320

Other (OTH)

AF:

0.0000537

AC:

AN:

55894

⚠️ The allele balance in gnomAD4 Exomes is highly skewed from 0.5 (p-value = 0.000000), which strongly suggests a high chance of mosaicism in these individuals.

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.389

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:

0.0000263

AC:

AN:

151962

Hom.:

Cov.:

AF XY:

0.0000135

AC XY:

AN XY:

74222

show subpopulations

African (AFR)

AF:

0.00

AC:

AN:

41394

American (AMR)

AF:

0.00

AC:

AN:

15252

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3466

East Asian (EAS)

AF:

0.00

AC:

AN:

5200

South Asian (SAS)

AF:

0.00

AC:

AN:

4820

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10586

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.0000589

AC:

AN:

67926

Other (OTH)

AF:

0.00

AC:

AN:

2092

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.537

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.00

Hom.:

Bravo

AF:

0.0000264

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:2

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

not specified

Benign:1

PreventionGenetics, part of Exact Sciences

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Facioscapulohumeral muscular dystrophy 2

Benign:1

Dec 10, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

PhyloP100

-0.24

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.070

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