18-33740444-G-T

Position:

• chr18-33740444-G-T

Variant summary

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

The NM_030632.3(ASXL3):​c.3039+1G>T variant causes a splice donor change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency: Genomes: not found (cov: 32)
• Consequence: ASXL3 NM_030632.3 splice_donor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 8.74

Genes affected

ASXL3 (HGNC:29357): (ASXL transcriptional regulator 3) This gene encodes a protein containing a plant homeodomain (PHD) zinc finger domain that plays a role in the regulation of gene transcription. The encoded protein has been shown to negatively regulate lipogenesis by binding to and inhibiting the transcriptional activity of two nuclear hormone receptors, oxysterols receptor LXR-alpha (LXRalpha) and thyroid hormone receptor beta (TRbeta). The encoded protein may also inhibit histone deubiquitination. Mutations in this gene have been identified in human patients with Bainbridge-Ropers syndrome, which is characterized by feeding difficulties, developmental delay and other features. [provided by RefSeq, May 2017]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 18-33740444-G-T is Pathogenic according to our data. Variant chr18-33740444-G-T is described in ClinVar as [Pathogenic]. Clinvar id is 1328153.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
ASXL3	NM_030632.3	c.3039+1G>T		splice_donor_variant		ENST00000269197.12	NP_085135.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
ASXL3	ENST00000269197.12	c.3039+1G>T		splice_donor_variant		5	NM_030632.3	ENSP00000269197	P4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Severe feeding difficulties-failure to thrive-microcephaly due to ASXL3 deficiency syndrome Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Aug 23, 2021

The ASXL3 c.3039+1G>T variant occurs in a canonical splice site (donor) of exon 11, which is the penultimate exon, and is therefore predicted to disrupt the normal gene product. A literature search was performed for the gene and the cDNA change but no publications were found based on this search. However, the c.3039+1G>A variant, which is a different nucleotide change affecting the same donor splice site position, has been reported in a de novo state in a patient in the literature (Hori et al. 2016). This variant is not found in the Genome Aggregation Database in a region of good sequence coverage, indicating the variant is rare. Based on the available evidence, the c.3039+1G>T variant is classified as pathogenic for Bainbridge-Ropers syndrome. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.20
CADD	Pathogenic	34
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	1.0	D
MutationTaster	Benign	1.0	D
GERP RS		5.6

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.97		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.23		Position offset: 4
DS_DL_spliceai		0.97		Position offset: -1

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

Publications

No publications associated with this variant yet.

Other links and lift over

hg19: chr18-31320408;