13-99984944-A-T

Variant names:

• chr13-99984944-A-T
• rs1555332361
• NM_007129.5:c.1076-2A>T

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_007129.5(ZIC2):​c.1076-2A>T variant causes a splice acceptor, intron 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: ZIC2 NM_007129.5 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 9.26
• Publications: 0 publications found

Genes affected

ZIC2 (HGNC:12873): (Zic family member 2) This gene encodes a member of the ZIC family of C2H2-type zinc finger proteins. This protein functions as a transcriptional repressor and may regulate tissue specific expression of dopamine receptor D1. Expansion of an alanine repeat in the C-terminus of the encoded protein and other mutations in this gene cause holoprosencephaly type 5. Holoprosencephaly is the most common structural anomaly of the human brain. A polyhistidine tract polymorphism in this gene may be associated with increased risk of neural tube defects. This gene is closely linked to a gene encoding zinc finger protein of the cerebellum 5, a related family member on chromosome 13. [provided by RefSeq, Jul 2016]

ZIC2 Gene-Disease associations (from GenCC):

• holoprosencephaly 5

  Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae), G2P, Genomics England PanelApp
• holoprosencephaly

  Inheritance: AR Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Pathogenic. The variant received 12 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, Cryptic splice site detected, with MaxEntScore 5.6, offset of -26, new splice context is: caggctctgggtgtctgcAGcca. 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
• PP5: Variant 13-99984944-A-T is Pathogenic according to our data. Variant chr13-99984944-A-T is described in ClinVar as Pathogenic. ClinVar VariationId is 468364.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
ZIC2	NM_007129.5	c.1076-2A>T		splice_acceptor_variant, intron_variant	Intron 1 of 2	ENST00000376335.8	NP_009060.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
ZIC2	ENST00000376335.8	c.1076-2A>T		splice_acceptor_variant, intron_variant	Intron 1 of 2	1	NM_007129.5	ENSP00000365514.3
ZIC2	ENST00000477213.1	n.156A>T		non_coding_transcript_exon_variant	Exon 1 of 2	2
ZIC2	ENST00000468291.1	n.50-2A>T		splice_acceptor_variant, intron_variant	Intron 1 of 2	2
ZIC2	ENST00000490085.5	n.122-2A>T		splice_acceptor_variant, intron_variant	Intron 1 of 2	3

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

Holoprosencephaly 5 Pathogenic:1

Sep 16, 2016

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change affects an acceptor splice site in intron 1 of the ZIC2 gene. It is expected to disrupt mRNA splicing and likely results in an absent or disrupted protein product. This variant has not been reported in the literature in an individual with a ZIC2-related disease.  However, a sequence change at an adjacent nucleotide that affects the same intron 1 acceptor splice site (c.1076-1G>A) has been reported in three individuals affected with holoprosencephaly (PMID: 19177455). Family studies have indicated that this variant was not present in the parents of an individual with holoprosencephaly, which suggests that it was de novo in that affected individual. For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.60	D
BayesDel_noAF	Uncertain	0.020
CADD	Pathogenic	34
DANN	Uncertain	0.99
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.87
FATHMM_MKL	Uncertain	0.92	D
PhyloP100		9.3
GERP RS		4.5
Mutation Taster		=6/94	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.95
SpliceAI score (max)		1.0		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.25		Position offset: -24
DS_AL_spliceai		1.0		Position offset: 2

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

Other links and lift over

dbSNP: rs1555332361; hg19: chr13-100637198;