chr20-32434429-CA-C

Variant names:

• chr20-32434429-CA-C
• NM_015338.6:c.1720-2delA

Variant summary

Our verdict is Pathogenic. The variant received 10 ACMG points: 10P and 0B. PVS1 PM2

The NM_015338.6(ASXL1):​c.1720-2delA variant causes a splice acceptor, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. 1/1 splice prediction tools predicting alterations to normal splicing. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar.

• Frequency: Genomes: not found (cov: 32)
• Consequence: ASXL1 NM_015338.6 splice_acceptor, intron
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 8.95
• Publications: 0 publications found

Genes affected

ASXL1 (HGNC:18318): (ASXL transcriptional regulator 1) This gene is similar to the Drosophila additional sex combs gene, which encodes a chromatin-binding protein required for normal determination of segment identity in the developing embryo. The protein is a member of the Polycomb group of proteins, which are necessary for the maintenance of stable repression of homeotic and other loci. The protein is thought to disrupt chromatin in localized areas, enhancing transcription of certain genes while repressing the transcription of other genes. The protein encoded by this gene functions as a ligand-dependent co-activator for retinoic acid receptor in cooperation with nuclear receptor coactivator 1. Mutations in this gene are associated with myelodysplastic syndromes and chronic myelomonocytic leukemia. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Sep 2009]

ASXL1 Gene-Disease associations (from GenCC):

• Bohring-Opitz syndrome

  Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Labcorp Genetics (formerly Invitae), ClinGen, Orphanet, Laboratory for Molecular Medicine, G2P, Illumina

ACMG classification

Our verdict: Pathogenic. The variant received 10 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 3.7, offset of 40, new splice context is: accaccctgggtggttaaAGgtc. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_015338.6. 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
	ASXL1	NM_015338.6	MANE Select	c.1720-2delA		splice_acceptor intron	N/A	NP_056153.2
	ASXL1	NM_001363734.1		c.1537-2delA		splice_acceptor intron	N/A	NP_001350663.1	A0A2R8Y5U1

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	ASXL1	ENST00000375687.10	TSL:5 MANE Select	c.1720-2delA		splice_acceptor intron	N/A	ENSP00000364839.4	Q8IXJ9-1
	ASXL1	ENST00000306058.9	TSL:1	c.1705-2delA		splice_acceptor intron	N/A	ENSP00000305119.5	Q76L82
	ASXL1	ENST00000905973.1		c.1717-2delA		splice_acceptor intron	N/A	ENSP00000576032.1

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
PhyloP100		8.9

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.96		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.23		Position offset: 43
DS_AL_spliceai		0.96		Position offset: 3

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

Other links and lift over

hg19: chr20-31022232;