rs1555146021

Positions:

• chr11-71438902-T-C

Variant summary

Our verdict is Pathogenic. Variant got 14 ACMG points: 14P and 0B. PM1 PM2 PP3_Moderate PP5_Very_Strong

The NM_001360.3(DHCR7):​c.808A>G​(p.Met270Val) variant causes a missense change. The variant allele was found at a frequency of 0.000000684 in 1,461,552 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 Likely pathogenic (★★).

• Frequency:
  • Genomes: not found (cov: 34)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: DHCR7 NM_001360.3 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:2 U:1
• Conservation: PhyloP100: 6.97

Genes affected

DHCR7 (HGNC:2860): (7-dehydrocholesterol reductase) This gene encodes an enzyme that removes the C(7-8) double bond in the B ring of sterols and catalyzes the conversion of 7-dehydrocholesterol to cholesterol. This gene is ubiquitously expressed and its transmembrane protein localizes to the endoplasmic reticulum membrane and nuclear outer membrane. Mutations in this gene cause Smith-Lemli-Opitz syndrome (SLOS); a syndrome that is metabolically characterized by reduced serum cholesterol levels and elevated serum 7-dehydrocholesterol levels and phenotypically characterized by cognitive disability, facial dysmorphism, syndactyly of second and third toes, and holoprosencephaly in severe cases to minimal physical abnormalities and near-normal intelligence in mild cases. Alternative splicing results in multiple transcript variants that encode the same protein.[provided by RefSeq, Aug 2009]

DHCR7 (HGNC:):

ACMG classification

Verdict is Pathogenic. Variant got 14 ACMG points.

• PM1: In a transmembrane_region Helical (size 20) in uniprot entity DHCR7_HUMAN there are 6 pathogenic changes around while only 0 benign (100%) in NM_001360.3
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.842
• PP5: Variant 11-71438902-T-C is Pathogenic according to our data. Variant chr11-71438902-T-C is described in ClinVar as [Likely_pathogenic]. Clinvar id is 556307.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr11-71438902-T-C is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
DHCR7	NM_001360.3	c.808A>G	p.Met270Val	missense_variant	7/9	ENST00000355527.8	NP_001351.2
DHCR7	NM_001163817.2	c.808A>G	p.Met270Val	missense_variant	7/9		NP_001157289.1
DHCR7	XM_011544777.3	c.808A>G	p.Met270Val	missense_variant	7/9

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
DHCR7	ENST00000355527.8	c.808A>G	p.Met270Val	missense_variant	7/9	1	NM_001360.3	ENSP00000347717.4
DHCR7	ENST00000685320.1	c.223A>G	p.Met75Val	missense_variant	6/8			ENSP00000509319.1

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461552 Hom.: 0 Cov.: 33 AF XY: 0.00000138 AC XY: 1 AN XY: 727074

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.0000252

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 34

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:2 Uncertain:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Smith-Lemli-Opitz syndrome Pathogenic:2 Uncertain:1

Likely pathogenic, criteria provided, single submitter	clinical testing	Baylor Genetics	Oct 03, 2023	- -
Pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Sep 12, 2023	For these reasons, this variant has been classified as Pathogenic. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt DHCR7 protein function. ClinVar contains an entry for this variant (Variation ID: 556307). This missense change has been observed in individual(s) with Smith-Lemli-Opitz syndrome (PMID: 18249054). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces methionine, which is neutral and non-polar, with valine, which is neutral and non-polar, at codon 270 of the DHCR7 protein (p.Met270Val). -
Uncertain significance, flagged submission	clinical testing	Counsyl	Jan 24, 2018	- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Uncertain	0.44
BayesDel_addAF	Pathogenic	0.53	D
BayesDel_noAF	Pathogenic	0.52
CADD	Uncertain	24
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.98	D;D;D;D;.
Eigen	Uncertain	0.39
Eigen_PC	Uncertain	0.34
FATHMM_MKL	Pathogenic	0.97	D
LIST_S2	Uncertain	0.93	.;D;D;D;D
M_CAP	Uncertain	0.29	D
MetaRNN	Pathogenic	0.84	D;D;D;D;D
MetaSVM	Pathogenic	0.86	D
MutationAssessor	Uncertain	2.7	M;M;.;.;.
PrimateAI	Uncertain	0.60	T
PROVEAN	Uncertain	-2.5	D;D;D;N;D
REVEL	Pathogenic	0.84
Sift	Uncertain	0.013	D;D;D;D;D
Sift4G	Uncertain	0.014	D;D;D;D;.
Polyphen		0.96	D;D;.;.;.
Vest4		0.92
MutPred		0.59		Loss of catalytic residue at V266 (P = 0.0487);Loss of catalytic residue at V266 (P = 0.0487);.;.;.;
MVP		0.94
MPC		0.21
ClinPred		0.93	D
GERP RS		4.5
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.68
gMVP		0.97

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.010		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: rs1555146021; hg19: chr11-71149948;