chr11-71437868-C-G

Variant names:

• chr11-71437868-C-G
• rs142808899
• NM_001360.3:c.907G>C

Variant summary

Our verdict is Pathogenic. The variant received 26 ACMG points: 26P and 0B. PS1_Very_Strong PM1 PM2 PM5 PP3_Strong PP5_Very_Strong

The NM_001360.3(DHCR7):​c.907G>C​(p.Gly303Arg) variant causes a missense change. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Another nucleotide change resulting in the same amino acid substitution has been previously reported as Likely pathogenic in ClinVar. Another variant affecting the same amino acid position, but resulting in a different missense (i.e. G303W) has been classified as Likely pathogenic.

• Frequency: Genomes: not found (cov: 34)
• Consequence: DHCR7 NM_001360.3 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 6.89
• Publications: 0 publications found

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 Gene-Disease associations (from GenCC):

• Smith-Lemli-Opitz syndrome

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, G2P, Myriad Women’s Health, Laboratory for Molecular Medicine, ClinGen, Labcorp Genetics (formerly Invitae)

ACMG classification

Our verdict: Pathogenic. The variant received 26 ACMG points.

• PS1: Transcript NM_001360.3 (DHCR7) is affected with MISSENSE_VARIANT having same AA change as one Pathogenic present in ClinVar.
• PM1: In a hotspot region, there are 10 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 7 uncertain in NM_001360.3
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chr11-71437868-C-A is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 640944.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.99
• PP5: Variant 11-71437868-C-G is Pathogenic according to our data. Variant chr11-71437868-C-G is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 2793342.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
DHCR7	NM_001360.3	c.907G>C	p.Gly303Arg	missense_variant	Exon 8 of 9	ENST00000355527.8	NP_001351.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
DHCR7	ENST00000355527.8	c.907G>C	p.Gly303Arg	missense_variant	Exon 8 of 9	1	NM_001360.3	ENSP00000347717.4
DHCR7	ENST00000685320.1	c.322G>C	p.Gly108Arg	missense_variant	Exon 7 of 8			ENSP00000509319.1

Frequencies

GnomAD3 genomes Cov.: 34

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 34

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Smith-Lemli-Opitz syndrome Pathogenic:3

Apr 12, 2024

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

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Variant summary: DHCR7 c.907G>C (p.Gly303Arg) results in a non-conservative amino acid change in the encoded protein sequence. Five of five in-silico tools predict a damaging effect of the variant on protein function. The variant was absent in 251326 control chromosomes (gnomAD). Gly303Arg has been reported in the literature in individuals affected with Smith-Lemli-Opitz Syndrome (example: Garry_2010). A different variant with same amino acid effect has been classified as pathogenic by our lab and in ClinVar (CV ID 198773). These data indicate that the variant is likely to be associated with disease. The following publication has been ascertained in the context of this evaluation (PMID: 20440536).ClinVar contains an entry for this variant (Variation ID: 2793342). Based on the evidence outlined above, the variant was classified as pathogenic. -

Mar 15, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

For these reasons, this variant has been classified as Pathogenic. This variant disrupts the p.Gly303 amino acid residue in DHCR7. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 16044199, 20052364, 28503313). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. 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. A different variant (c.907G>A) giving rise to the same protein effect has been determined to be pathogenic (PMID: 16044199, 20052364, 28503313). This suggests that this variant is also likely to be causative of disease. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces glycine, which is neutral and non-polar, with arginine, which is basic and polar, at codon 303 of the DHCR7 protein (p.Gly303Arg). -

Apr 22, 2024

Fulgent Genetics, Fulgent Genetics

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.57	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	29
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.99	D;D;D;D
Eigen	Uncertain	0.53
Eigen_PC	Uncertain	0.49
FATHMM_MKL	Uncertain	0.94	D
LIST_S2	Pathogenic	0.98	.;D;D;D
M_CAP	Uncertain	0.26	D
MetaRNN	Pathogenic	0.99	D;D;D;D
MetaSVM	Uncertain	0.47	D
MutationAssessor	Pathogenic	4.3	H;H;.;.
PhyloP100		6.9
PrimateAI	Pathogenic	0.87	D
PROVEAN	Pathogenic	-7.6	D;D;D;D
REVEL	Pathogenic	0.99
Sift	Pathogenic	0.0	D;D;D;D
Sift4G	Pathogenic	0.0	D;D;D;D
Polyphen		1.0	D;D;.;.
Vest4		1.0
MutPred		0.95		Loss of catalytic residue at H299 (P = 0.2316);Loss of catalytic residue at H299 (P = 0.2316);.;.;
MVP		0.98
MPC		0.62
ClinPred		1.0	D
GERP RS		4.6
Varity_R		0.97
gMVP		1.0
Mutation Taster		=3/97	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: rs142808899; hg19: chr11-71148914;