chr7-66633445-G-A

Variant names:

• chr7-66633445-G-A
• rs1554397834
• NM_153033.5:c.314+1G>A

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PVS1_Strong PM2 PP5_Moderate

The NM_153033.5(KCTD7):​c.314+1G>A variant causes a splice donor, intron change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.000000684 in 1,461,866 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. 3/3 splice prediction tools predicting alterations to normal splicing. Variant has been reported in ClinVar as Likely pathogenic (★).

• Frequency:
  • Genomes: not found (cov: 31)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: KCTD7 NM_153033.5 splice_donor, intron
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 9.28
• Publications: 0 publications found

Genes affected

KCTD7 (HGNC:21957): (potassium channel tetramerization domain containing 7) This gene encodes a member of the potassium channel tetramerization domain-containing protein family. Family members are identified on a structural basis and contain an amino-terminal domain similar to the T1 domain present in the voltage-gated potassium channel. Mutations in this gene have been associated with progressive myoclonic epilepsy-3. Alternative splicing results in multiple transcript variants.[provided by RefSeq, Jan 2011]

KCTD7 Gene-Disease associations (from GenCC):

• progressive myoclonic epilepsy type 3

  Inheritance: AR Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Genomics England PanelApp, Ambry Genetics, G2P, Labcorp Genetics (formerly Invitae), Orphanet
• progressive myoclonus epilepsy

  Inheritance: AR Classification: DEFINITIVE Submitted by: ClinGen

ENSG00000284461 (HGNC:):

ACMG classification

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, product NOT destroyed by NMD, known LOF gene, truncates exone, which is 0.1954023 fraction of the gene. Cryptic splice site detected, with MaxEntScore 5.7, offset of -33, new splice context is: ccgGTactt. Cryptic site results in inframe change. If cryptic site found is not functional and variant results in exon loss, it results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 7-66633445-G-A is Pathogenic according to our data. Variant chr7-66633445-G-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 536951.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
KCTD7	NM_153033.5	c.314+1G>A		splice_donor_variant, intron_variant	Intron 2 of 3	ENST00000639828.2	NP_694578.1
KCTD7	NM_001167961.2	c.314+1G>A		splice_donor_variant, intron_variant	Intron 2 of 4		NP_001161433.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
KCTD7	ENST00000639828.2	c.314+1G>A		splice_donor_variant, intron_variant	Intron 2 of 3	2	NM_153033.5	ENSP00000492240.1
ENSG00000284461	ENST00000503687.2	n.144+4237G>A		intron_variant	Intron 1 of 12	2		ENSP00000421074.1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461866 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 727236

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: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86258

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53414

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5766

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111992

Other (OTH) AF: 0.00 AC: 0 AN: 60396

GnomAD4 genome Cov.: 31

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Progressive myoclonic epilepsy type 3 Pathogenic:1

Jan 24, 2018

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Donor and acceptor splice site variants typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in KCTD7 are known to be pathogenic (PMID: 22693283). In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site, but this prediction has not been confirmed by published transcriptional studies. This variant has not been reported in the literature in individuals with KCTD7-related disease. This variant is not present in population databases (ExAC no frequency). This sequence change affects a donor splice site in intron 2 of the KCTD7 gene. It is expected to disrupt RNA splicing and likely results in an absent or disrupted protein product. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.38
CADD	Pathogenic	36
DANN	Uncertain	1.0
Eigen	Pathogenic	1.1
Eigen_PC	Pathogenic	0.98
FATHMM_MKL	Pathogenic	0.98	D
PhyloP100		9.3
GERP RS		4.8
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Mutation Taster		=3/97	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.99		Details are displayed if max score is > 0.2
DS_DG_spliceai		0.89		Position offset: 40
DS_DL_spliceai		0.99		Position offset: -1

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

Other links and lift over

dbSNP: rs1554397834; hg19: chr7-66098432;