2-218782186-G-GC

Variant names:

• chr2-218782186-G-GC
• rs587778802
• NM_000784.4:c.5dupC

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_000784.4(CYP27A1):​c.5dupC​(p.Ala3CysfsTer178) variant causes a frameshift change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000289 in 1,384,028 control chromosomes in the GnomAD database, with no homozygous occurrence. Variant has been reported in ClinVar as Pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000029 (0 hom.)
• Consequence: CYP27A1 NM_000784.4 frameshift
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:6
• Conservation: PhyloP100: 0.512

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]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Loss of function variant, product does not undergo nonsense mediated mRNA decay. Variant located near the start codon (<100nt), not predicted to undergo nonsense mediated mRNA decay. There are 35 pathogenic variants in the truncated region.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 2-218782186-G-GC is Pathogenic according to our data. Variant chr2-218782186-G-GC is described in ClinVar as [Pathogenic]. Clinvar id is 65882.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
CYP27A1	NM_000784.4	c.5dupC	p.Ala3CysfsTer178	frameshift_variant	Exon 1 of 9	ENST00000258415.9	NP_000775.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
CYP27A1	ENST00000258415.9	c.5dupC	p.Ala3CysfsTer178	frameshift_variant	Exon 1 of 9	1	NM_000784.4	ENSP00000258415.4
CYP27A1	ENST00000445971.1	n.5dupC		non_coding_transcript_exon_variant	Exon 1 of 5	5		ENSP00000404945.1
CYP27A1	ENST00000466602.1	n.14dupC		non_coding_transcript_exon_variant	Exon 1 of 3	2
CYP27A1	ENST00000494263.5	n.439dupC		non_coding_transcript_exon_variant	Exon 1 of 7	2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000289 AC: 4 AN: 1384028 Hom.: 0 Cov.: 31 AF XY: 0.00000293 AC XY: 2 AN XY: 683002

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

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: 0.00000371

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 32

Bravo AF: 0.00000378

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:6

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Cholestanol storage disease Pathogenic:3

Aug 01, 2013

GeneReviews

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: curation

- -

Apr 25, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change creates a premature translational stop signal (p.Ala3Cysfs*178) in the CYP27A1 gene. It is expected to result in an absent or disrupted protein product. 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). This premature translational stop signal has been observed in individual(s) with cerebrotendinous xanthomatosis (PMID: 7860076). This variant is also known as c.6insC. ClinVar contains an entry for this variant (Variation ID: 65882). For these reasons, this variant has been classified as Pathogenic. -

Mar 01, 2024

Baylor Genetics

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

not provided Pathogenic:3

Sep 09, 2022

GeneDx

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Not observed at significant frequency in large population cohorts (gnomAD); Frameshift variant predicted to result in protein truncation or nonsense mediated decay in a gene for which loss of function is a known mechanism of disease; This variant is associated with the following publications: (PMID: 31589614, 7860076) -

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Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

-

Clinical Genetics, Academic Medical Center

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.0		Details are displayed if max score is > 0.2

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

Publications

LitVar

Other links and lift over

dbSNP: rs587778802; hg19: chr2-219646909;