2-218814971-C-G

Variant names:

• chr2-218814971-C-G
• rs560108684
• NM_000784.4:c.1537C>G

Variant summary

Our verdict is Likely pathogenic. The variant received 6 ACMG points: 6P and 0B. PM2 PM5 PP3_Moderate

The NM_000784.4(CYP27A1):​c.1537C>G​(p.Arg513Gly) variant causes a missense change. The variant allele was found at a frequency of 0.00000274 in 1,461,864 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. R513H) has been classified as Likely pathogenic.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000027 (0 hom.)
• Consequence: CYP27A1 NM_000784.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.65
• Publications: 0 publications found

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 Gene-Disease associations (from GenCC):

• cerebrotendinous xanthomatosis

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), Myriad Women’s Health, Genomics England PanelApp, G2P

ACMG classification

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

• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr2-218814972-G-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 449362.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.869

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000784.4. 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
	CYP27A1	NM_000784.4	MANE Select	c.1537C>G	p.Arg513Gly	missense	Exon 9 of 9	NP_000775.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	CYP27A1	ENST00000258415.9	TSL:1 MANE Select	c.1537C>G	p.Arg513Gly	missense	Exon 9 of 9	ENSP00000258415.4
	CYP27A1	ENST00000494263.5	TSL:2	n.2249C>G		non_coding_transcript_exon	Exon 7 of 7

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000274 AC: 4 AN: 1461864 Hom.: 0 Cov.: 32 AF XY: 0.00000138 AC XY: 1 AN XY: 727240

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44724

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26136

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.00 AC: 0 AN: 86254

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53418

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5768

European-Non Finnish (NFE) AF: 0.00000360 AC: 4 AN: 1111992

Other (OTH) AF: 0.00 AC: 0 AN: 60394

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Dec 09, 2024

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: CYP27A1 c.1537C>G (p.Arg513Gly) results in a non-conservative amino acid change in the encoded protein sequence. Four of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 251486 control chromosomes. The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. To our knowledge, no occurrence of c.1537C>G in individuals affected with Cerebrotendinous Xanthomatosis and no experimental evidence demonstrating its impact on protein function have been reported. No submitters have cited clinical-significance assessments for this variant to ClinVar. Based on the evidence outlined above, the variant was classified as uncertain significance.

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.60
BayesDel_addAF	Pathogenic	0.36	D
BayesDel_noAF	Pathogenic	0.27
CADD	Pathogenic	28
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.66	D
Eigen	Pathogenic	0.70
Eigen_PC	Uncertain	0.63
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Uncertain	0.91	D
M_CAP	Uncertain	0.20	D
MetaRNN	Pathogenic	0.87	D
MetaSVM	Uncertain	-0.067	T
MutationAssessor	Pathogenic	3.3	M
PhyloP100		3.6
PrimateAI	Benign	0.45	T
PROVEAN	Pathogenic	-5.6	D
REVEL	Uncertain	0.53
Sift	Pathogenic	0.0	D
Sift4G	Uncertain	0.0050	D
Polyphen		1.0	D
Vest4		0.81
MutPred		0.57		Loss of MoRF binding (P = 0.0064)
MVP		0.89
MPC		0.82
ClinPred		1.0	D
GERP RS		4.4
Varity_R		0.94
gMVP		0.95
Mutation Taster		=19/81	disease causing

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

Other links and lift over

dbSNP: rs560108684; hg19: chr2-219679694;