chr2-218809576-G-T

Position:

chr2-218809576-G-T

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PVS1_StrongPM2PP5_Very_Strong

The NM_000784.4(CYP27A1):c.256-1G>T variant causes a splice acceptor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000311 in 1,606,968 control chromosomes in the GnomAD database, with no homozygous occurrence. 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: 𝑓 0.0000066 ( 0 hom., cov: 30)

Exomes 𝑓: 0.0000027 ( 0 hom. )

Consequence

CYP27A1
NM_000784.4 splice_acceptor

Scores

Splicing: ADA: 1.000

Clinical Significance

Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:6

Conservation

PhyloP100: 9.36

Variant links:

Genes affected

CYP27A1 (HGNC:2605): (cytochrome P450 family 27 subfamily A member 1) This gene encodes a member of the cytochrome P450 superfamily of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. This mitochondrial protein oxidizes cholesterol intermediates as part of the bile synthesis pathway. Since the conversion of cholesterol to bile acids is the major route for removing cholesterol from the body, this protein is important for overall cholesterol homeostasis. Mutations in this gene cause cerebrotendinous xanthomatosis, a rare autosomal recessive lipid storage disease. [provided by RefSeq, Jul 2008]

CYP27A1 links:

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ACMG classification

Classification made for transcript

Verdict is Pathogenic. Variant got 14 ACMG points.

PVS1

Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.11904762 fraction of the gene. Cryptic splice site detected, with MaxEntScore 3.5, offset of 12, new splice context is: ctccacatgtgctttacaAGgcc. Cryptic site results in inframe 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 2-218809576-G-T is Pathogenic according to our data. Variant chr2-218809576-G-T is described in ClinVar as [Likely_pathogenic]. Clinvar id is 553433.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr2-218809576-G-T is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
CYP27A1	NM_000784.4 linkuse as main transcript	c.256-1G>T		splice_acceptor_variant		ENST00000258415.9	NP_000775.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
CYP27A1	ENST00000258415.9 linkuse as main transcript	c.256-1G>T		splice_acceptor_variant		1	NM_000784.4	ENSP00000258415	P1

Frequencies

GnomAD3 genomes

AF:

0.00000664

AC:

AN:

150622

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.00

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.0000670

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD4 exome

AF:

0.00000275

AC:

AN:

1456346

Hom.:

Cov.:

AF XY:

0.00000276

AC XY:

AN XY:

724528

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.0000225

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.00

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.00000180

Gnomad4 OTH exome

AF:

0.0000167

GnomAD4 genome

AF:

0.00000664

AC:

AN:

150622

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

73370

show subpopulations

Gnomad4 AFR

AF:

0.00

Gnomad4 AMR

AF:

0.0000670

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.00

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.00

Gnomad4 OTH

AF:

0.00

Bravo

AF:

0.0000189

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Cholestanol storage disease

Pathogenic:4

Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jan 17, 2024	This sequence change affects an acceptor splice site in intron 1 of the CYP27A1 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in CYP27A1 are known to be pathogenic (PMID: 9392430, 10775536, 26937392). This variant is not present in population databases (gnomAD no frequency). Disruption of this splice site has been observed in individual(s) with cerebrotendinous xanthomatosis (PMID: 25983621). ClinVar contains an entry for this variant (Variation ID: 553433). Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. For these reasons, this variant has been classified as Pathogenic. -
Pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Jan 28, 2023	- -
Pathogenic, criteria provided, single submitter	research	Unidad de Genómica Médica UC, Pontificia Universidad Católica de Chile	Apr 07, 2014	This patient is a compound heterozygote for the substitution c.256-1G>T that causes exon 2 skipping, leading to a premature stop codon in exon 3, and for the pathogenic mutation c.1183C>T(p.Arg395Cys). -
Likely pathogenic, criteria provided, single submitter	clinical testing	Counsyl	Aug 18, 2017	- -

not provided

Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Eurofins Ntd Llc (ga)

Aug 29, 2017

- -

CYP27A1-related disorder

Pathogenic:1

Pathogenic, no assertion criteria provided

clinical testing

PreventionGenetics, part of Exact Sciences

May 16, 2024

The CYP27A1 c.256-1G>T variant is predicted to disrupt the AG splice acceptor site and interfere with normal splicing. This variant was reported along with a known pathogenic CYP27A1 missense variant (c.1183C>T, p.Arg395Cys) in an individual with cerebrotendinous xanthomatosis (Smalley et al. 2015. PubMed ID: 25983621). RNA studies have shown that the c.256-1G>T variant results in skipping of exon 2 (Smalley et al. 2015. PubMed ID: 25983621). This variant has not been reported in a large population database, indicating it is rare. Variants that disrupt the consensus splice acceptor site in CYP27A1 are expected to be pathogenic. Taken together, this variant is interpreted as pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.63

BayesDel_noAF

Pathogenic

0.29

CADD

Pathogenic

DANN

Uncertain

1.0

Eigen

Pathogenic

1.2

Eigen_PC

Pathogenic

0.99

FATHMM_MKL

Pathogenic

1.0

MutationTaster

Benign

1.0

GERP RS

5.7

RBP_binding_hub_radar

0.0

RBP_regulation_power_radar

1.1

Splicing

Name

Calibrated prediction

Score

Prediction

dbscSNV1_ADA

Pathogenic

1.0

dbscSNV1_RF

Pathogenic

0.94

SpliceAI score (max)

0.96

Details are displayed if max score is > 0.2

DS_AG_spliceai

0.28

Position offset: 47

DS_AL_spliceai

0.96

Position offset: 1

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over