rs1554397774

Positions:

• chr7-66633273-A-G

Variant summary

Our verdict is Pathogenic. Variant got 18 ACMG points: 18P and 0B. PVS1 PM2 PP5_Very_Strong

The NM_153033.5(KCTD7):​c.145-2A>G variant causes a splice acceptor change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000342 in 1,461,566 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: 0.0000034 (0 hom.)
• Consequence: KCTD7 NM_153033.5 splice_acceptor
• Scores: Splicing: ADA: 1.000
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:3
• Conservation: PhyloP100: 8.28

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]

ACMG classification

Verdict is Pathogenic. Variant got 18 ACMG points.

• PVS1: Splicing +-2 bp (donor or acceptor) variant, LoF is a know mechanism of disease, No cryptic splice site detected. Exon removal results in frameshift change.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 7-66633273-A-G is Pathogenic according to our data. Variant chr7-66633273-A-G is described in ClinVar as [Likely_pathogenic]. Clinvar id is 520584.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chr7-66633273-A-G is described in Lovd as [Likely_pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
KCTD7	NM_153033.5	c.145-2A>G		splice_acceptor_variant		ENST00000639828.2	NP_694578.1
KCTD7	NM_001167961.2	c.145-2A>G		splice_acceptor_variant			NP_001161433.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
KCTD7	ENST00000639828.2	c.145-2A>G		splice_acceptor_variant		2	NM_153033.5	ENSP00000492240	A1

Frequencies

GnomAD3 genomes Cov.: 31

GnomAD4 exome AF: 0.00000342 AC: 5 AN: 1461566 Hom.: 0 Cov.: 32 AF XY: 0.00000275 AC XY: 2 AN XY: 727096

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000360

Gnomad4 OTH exome AF: 0.0000166

GnomAD4 genome Cov.: 31

Bravo AF: 0.0000113

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:3

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Progressive myoclonic epilepsy type 3 Pathogenic:2

Likely pathogenic, criteria provided, single submitter	clinical testing	New York Genome Center	Aug 14, 2020	- -
Likely pathogenic, criteria provided, single submitter	clinical testing	Labcorp Genetics (formerly Invitae), Labcorp	Jun 20, 2022	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. ClinVar contains an entry for this variant (Variation ID: 520584). Disruption of this splice site has been observed in individual(s) with progressive myoclonus epilepsy (PMID: 26795593). This variant is not present in population databases (gnomAD no frequency). This sequence change affects an acceptor splice site in intron 1 of the KCTD7 gene. It is expected to disrupt RNA splicing. Variants that disrupt the donor or acceptor splice site typically lead to a loss of protein function (PMID: 16199547), and loss-of-function variants in KCTD7 are known to be pathogenic (PMID: 22693283). -

Inborn genetic diseases Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Ambry Genetics

Oct 23, 2014

The c.145-2A>G intronic alteration consists of a A to G substitution 2 nucleotides before coding exon 2 in the KCTD7 gene. The alteration is not observed in healthy cohorts:_x000D_ Based on data from the NHLBI Exome Sequencing Project (ESP), the KCTD7 c.145-2A>G alteration was not observed among 6,503 individuals tested. Allele frequency data for this nucleotide position are not currently available from the 1000 Genomes Project and the alteration is not currently listed in the Database of Single Nucleotide Polymorphisms (dbSNP)._x000D_ Though some variants may appear to be rare due to database-specific ethnic underrepresentation, rare missense alleles commonly exhibit a deleterious effect on protein function (Kryukov, 2007; Tennessen, 2012). IF USED, PULL THESE INTO REFERENCES:_x000D_ Kryukov GV, et al. (2007) Am J Hum Genet 80:727-739. Tennessen JA, et al. (2012) Science 337(64):64-69. The alteration is predicted to affect splicing by in silico models:_x000D_ Based on BDGP and ESEfinder splice site in silico tools, this alteration is predicted to abolish the native splice acceptor site; however, direct evidence is unavailable. Based on the available evidence, this alteration is classified as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.21
CADD	Pathogenic	34
DANN	Uncertain	1.0
Eigen	Pathogenic	1.0
Eigen_PC	Pathogenic	0.86
FATHMM_MKL	Pathogenic	1.0	D
MutationTaster	Benign	1.0	D
GERP RS		4.8

Splicing

Name	Calibrated prediction	Score	Prediction
dbscSNV1_ADA	Pathogenic	1.0
dbscSNV1_RF	Pathogenic	0.93
SpliceAI score (max)		0.98		Details are displayed if max score is > 0.2
DS_AG_spliceai		0.55		Position offset: 11
DS_AL_spliceai		0.98		Position offset: 2

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

Publications

LitVar

Other links and lift over

dbSNP: rs1554397774; hg19: chr7-66098260;