18-2750479-A-C

Variant names:

• chr18-2750479-A-C
• NM_015295.3:c.4137A>C
• SMCHD1 p.Ala1379Ala

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PM2 BP4_Strong BP7

The NM_015295.3(SMCHD1):​c.4137A>C​(p.Ala1379Ala) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. A1379A) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 31)
• Consequence: SMCHD1 NM_015295.3 synonymous
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 0.324
• Publications: 0 publications found

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: PanelApp Australia, Ambry Genetics, Illumina, ClinGen, G2P, Labcorp Genetics (formerly Invitae)
• 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

ENSG00000266049 (HGNC:):

ACMG classification

Our verdict: Likely_benign. The variant received -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.64).
• BP7: Synonymous conserved (PhyloP=0.324 with no splicing effect.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_015295.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SMCHD1	NM_015295.3	MANE Select	c.4137A>C	p.Ala1379Ala	synonymous	Exon 32 of 48	NP_056110.2

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	SMCHD1	ENST00000320876.11	TSL:5 MANE Select	c.4137A>C	p.Ala1379Ala	synonymous	Exon 32 of 48	ENSP00000326603.7	A6NHR9-1
	SMCHD1	ENST00000939310.1		c.4050A>C	p.Ala1350Ala	synonymous	Exon 32 of 48	ENSP00000609369.1
	SMCHD1	ENST00000688342.1		c.4137A>C	p.Ala1379Ala	synonymous	Exon 32 of 47	ENSP00000508422.1	A0A8I5KRS9

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 31

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.64
CADD	Benign	4.2
DANN	Benign	0.59
PhyloP100		0.32
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.020		Details are displayed if max score is > 0.2

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

hg19: chr18-2750477;