chr9-114270726-A-G

Variant names:

• chr9-114270726-A-G
• rs1554821679
• NM_032888.4:c.3556-2A>G

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PVS1_Moderate PM2 PP5_Moderate

The NM_032888.4(COL27A1):​c.3556-2A>G variant causes a splice acceptor, intron change. The variant was absent in control chromosomes in GnomAD project. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Pathogenic (★).

• Frequency: Genomes: not found (cov: 33)
• Consequence: COL27A1 NM_032888.4 splice_acceptor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Pathogenic criteria provided, single submitter P:2
• Conservation: PhyloP100: 4.99
• Publications: 2 publications found

Genes affected

COL27A1 (HGNC:22986): (collagen type XXVII alpha 1 chain) This gene encodes a member of the fibrillar collagen family, and plays a role during the calcification of cartilage and the transition of cartilage to bone. The encoded protein product is a preproprotein. It includes an N-terminal signal peptide, which is followed by an N-terminal propetide, mature peptide and a C-terminal propeptide. The N-terminal propeptide contains thrombospondin N-terminal-like and laminin G-like domains. The mature peptide is a major triple-helical region. The C-terminal propeptide, also known as COLFI domain, plays crucial roles in tissue growth and repair. Mutations in this gene cause Steel syndrome. Alternatively spliced transcript variants have been found, but the full-length nature of some variants has not been determined. [provided by RefSeq, Sep 2014]

COL27A1 Gene-Disease associations (from GenCC):

• Steel syndrome

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, G2P, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Likely_pathogenic. The variant received 6 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.009672219 fraction of the gene. Cryptic splice site detected, with MaxEntScore 4.6, offset of -36, new splice context is: caccggggcctcctccccAGtaa. Cryptic site results in inframe 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 9-114270726-A-G is Pathogenic according to our data. Variant chr9-114270726-A-G is described in ClinVar as Pathogenic. ClinVar VariationId is 559511.Status of the report is criteria_provided_single_submitter, 1 stars.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_032888.4. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	COL27A1	NM_032888.4	MANE Select	c.3556-2A>G		splice_acceptor intron	N/A	NP_116277.2

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	COL27A1	ENST00000356083.8	TSL:1 MANE Select	c.3556-2A>G		splice_acceptor intron	N/A	ENSP00000348385.3
	COL27A1	ENST00000494090.6	TSL:1	n.*993-2A>G		splice_acceptor intron	N/A	ENSP00000432928.1
	COL27A1	ENST00000477421.2	TSL:2	n.489-2A>G		splice_acceptor intron	N/A

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 28

GnomAD4 genome Cov.: 33

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, single submitter

Submissions by phenotype

Steel syndrome Pathogenic:2

Oct 04, 2024

Al Jalila Children’s Genomics Center, Al Jalila Childrens Speciality Hospital

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: research

PVS1,PM2

Aug 10, 2018

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Uncertain	0.014	T
BayesDel_noAF	Benign	-0.22
CADD	Pathogenic	27
DANN	Uncertain	0.99
Eigen	Pathogenic	0.86
Eigen_PC	Uncertain	0.65
FATHMM_MKL	Uncertain	0.93	D
PhyloP100		5.0
GERP RS		4.9
Mutation Taster		=5/95	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.74
SpliceAI score (max)		0.94		Details are displayed if max score is > 0.2
DS_AL_spliceai		0.94		Position offset: 2

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

Other links and lift over

dbSNP: rs1554821679; hg19: chr9-117033006;