NM_024926.4:c.4-1G>C

Variant names:

• chr7-139134654-G-C
• rs2130770516
• NM_024926.4:c.4-1G>C

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1_Moderate PM2 PP5_Very_Strong

The NM_024926.4(IFT56):​c.4-1G>C 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 Likely pathogenic (★★).

• Frequency: Genomes: not found (cov: 31)
• Consequence: IFT56 NM_024926.4 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 7.93
• Publications: 0 publications found

Genes affected

IFT56 (HGNC:21882): (intraflagellar transport 56) Predicted to enable intraciliary transport particle B binding activity. Predicted to be involved in cilium organization; protein localization to cilium; and smoothened signaling pathway. Predicted to act upstream of or within manchette assembly. Predicted to be located in cilium. Predicted to be part of intraciliary transport particle B. Predicted to be active in ciliary basal body and ciliary base. [provided by Alliance of Genome Resources, Apr 2022]

IFT56 Gene-Disease associations (from GenCC):

• biliary, renal, neurologic, and skeletal syndrome

  Inheritance: AR Classification: STRONG Submitted by: Labcorp Genetics (formerly Invitae)

ACMG classification

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

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.08288288 fraction of the gene. Cryptic splice site detected, with MaxEntScore 5.5, offset of 11, new splice context is: cttttacacatgctttcaAGggc. Cryptic site results in frameshift change. If cryptic site found is not functional and variant results in exon loss, it results in inframe change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 7-139134654-G-C is Pathogenic according to our data. Variant chr7-139134654-G-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 1251992.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
IFT56	NM_024926.4	c.4-1G>C		splice_acceptor_variant, intron_variant	Intron 1 of 17	ENST00000464848.5	NP_079202.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
IFT56	ENST00000464848.5	c.4-1G>C		splice_acceptor_variant, intron_variant	Intron 1 of 17	1	NM_024926.4	ENSP00000419279.1
IFT56	ENST00000478836.6	c.4-1G>C		splice_acceptor_variant, intron_variant	Intron 1 of 15	2		ENSP00000419178.2

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome Cov.: 30

GnomAD4 genome Cov.: 31

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Biliary, renal, neurologic, and skeletal syndrome Pathogenic:2

Oct 04, 2021

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Mar 14, 2024

Genomic Medicine Center of Excellence, King Faisal Specialist Hospital and Research Centre

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Hydrocephalus Pathogenic:1

Apr 29, 2021

Genomic Medicine Center of Excellence, King Faisal Specialist Hospital and Research Centre

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: research

- -

not provided Pathogenic:1

Mar 11, 2024

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Canonical splice site variant predicted to result in an in-frame loss of the adjacent exon in a gene for which loss of function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); This variant is associated with the following publications: (PMID: 32552793, 31595528, 34177428) -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.42	D
BayesDel_noAF	Pathogenic	0.36
CADD	Pathogenic	35
DANN	Uncertain	1.0
Eigen	Pathogenic	1.2
Eigen_PC	Pathogenic	1.1
FATHMM_MKL	Pathogenic	0.98	D
PhyloP100		7.9
GERP RS		5.7
Mutation Taster		=0/100	disease causing

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.94
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.50		Position offset: 12
DS_AL_spliceai		0.99		Position offset: 1

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

Other links and lift over

dbSNP: rs2130770516; hg19: chr7-138819400;