8-93791324-G-A

Position:

• chr8-93791324-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3 PP5

The NM_153704.6(TMEM67):​c.1575+5G>A variant causes a splice region, intron change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 33)
• Consequence: TMEM67 NM_153704.6 splice_region, intron
• Scores: Splicing: ADA: 0.9999
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:1
• Conservation: PhyloP100: 8.28

Genes affected

TMEM67 (HGNC:28396): (transmembrane protein 67) The protein encoded by this gene localizes to the primary cilium and to the plasma membrane. The gene functions in centriole migration to the apical membrane and formation of the primary cilium. Multiple transcript variants encoding different isoforms have been found for this gene. Defects in this gene are a cause of Meckel syndrome type 3 (MKS3) and Joubert syndrome type 6 (JBTS6). [provided by RefSeq, Nov 2008]

TMEM67 (HGNC:):

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: Multiple lines of computational evidence support a deleterious effect 4: dbscSNV1_ADA, dbscSNV1_RF, max_spliceai, phyloP100way_vertebrate [when BayesDel_noAF, Cadd was below the threshold]
• PP5: Variant 8-93791324-G-A is Pathogenic according to our data. Variant chr8-93791324-G-A is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 495328.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=1, Likely_pathogenic=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
TMEM67	NM_153704.6	c.1575+5G>A		splice_region_variant, intron_variant		ENST00000453321.8	NP_714915.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
TMEM67	ENST00000453321.8	c.1575+5G>A		splice_region_variant, intron_variant		1	NM_153704.6	ENSP00000389998.3

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 24

GnomAD4 genome Cov.: 33

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:1

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Joubert syndrome 6 Pathogenic:1

Likely pathogenic, criteria provided, single submitter

research

Broad Center for Mendelian Genomics, Broad Institute of MIT and Harvard

Jun 26, 2017

Despite not meeting strict ACMG criteria for Likely Pathogenic, we believe this is the correct classification, due to the specificity of the phenotype (PP4) as well as PM2: Absent from gnomAD (reasonable coverage, exomes 40X, genomes 30X). PM3: Observed in trans with a pathogenic variant. PP3 donor +5 position predicted to disrupt splicing. -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

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

Jul 15, 2022

Variant summary: TMEM67 c.1575+5G>A alters a conserved nucleotide located close to a canonical splice site and therefore could affect mRNA splicing, leading to a significantly altered protein sequence. Several computational tools predict a significant impact on normal splicing: One predict the variant abolishes a 5 prime splicing donor site; two predict the variant weakens a 5 prime donor site. However, these predictions have yet to be confirmed by functional studies. The variant was absent in 247428 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.1575+5G>A in individuals affected with Joubert Syndrome And Related Disorders and no experimental evidence demonstrating its impact on protein function have been reported. One clinical diagnostic laboratory has submitted clinical-significance assessments for this variant to ClinVar after 2014 without evidence for independent evaluation. One laboratory classified the variant as likely pathogenic. Based on the evidence outlined above, the variant was classified as uncertain significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.17
CADD	Benign	21
DANN	Uncertain	0.98

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.96
SpliceAI score (max)		0.71		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.71		Position offset: -5

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

Publications

LitVar

Other links and lift over

dbSNP: rs1554555063; hg19: chr8-94803552;