9-135770911-G-T

Variant names:

• chr9-135770911-G-T
• rs764141661
• NM_020822.3:c.1824G>T

Variant summary

Our verdict is Likely benign. The variant received -3 ACMG points: 2P and 5B. PM2 BP4_Strong BP7

The NM_020822.3(KCNT1):​c.1824G>T​(p.Leu608Leu) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000000687 in 1,456,186 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Synonymous variant affecting the same amino acid position (i.e. L608L) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 6.9e-7 (0 hom.)
• Consequence: KCNT1 NM_020822.3 synonymous
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 3.08
• Publications: 1 publications found

Genes affected

KCNT1 (HGNC:18865): (potassium sodium-activated channel subfamily T member 1) Potassium channels represent the most complex class of voltage-gated ion channels from both functional and structural standpoints. Their diverse functions include regulating neurotransmitter release, heart rate, insulin secretion, neuronal excitability, epithelial electrolyte transport, smooth muscle contraction, and cell volume. This gene encodes a sodium-activated potassium channel subunit which is thought to function in ion conductance and developmental signaling pathways. Mutations in this gene cause the early-onset epileptic disorders, malignant migrating partial seizures of infancy and autosomal dominant nocturnal frontal lobe epilepsy. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Dec 2012]

KCNT1 Gene-Disease associations (from GenCC):

• childhood-onset epilepsy syndrome

  Inheritance: AD Classification: DEFINITIVE Submitted by: ClinGen
• developmental and epileptic encephalopathy, 14

  Inheritance: AD Classification: DEFINITIVE, STRONG, MODERATE Submitted by: Labcorp Genetics (formerly Invitae), Ambry Genetics, G2P
• malignant migrating partial seizures of infancy

  Inheritance: AD Classification: DEFINITIVE, SUPPORTIVE Submitted by: G2P, Orphanet
• autosomal dominant nocturnal frontal lobe epilepsy 5

  Inheritance: AD Classification: STRONG, MODERATE Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
• autosomal dominant nocturnal frontal lobe epilepsy

  Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_benign. The variant received -3 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.49).
• BP7: Synonymous conserved (PhyloP=3.08 with no splicing effect.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_020822.3. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNT1	NM_020822.3	MANE Select	c.1824G>T	p.Leu608Leu	synonymous	Exon 18 of 31	NP_065873.2
	KCNT1	NM_001272003.2		c.1689G>T	p.Leu563Leu	synonymous	Exon 17 of 31	NP_001258932.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNT1	ENST00000371757.7	TSL:1 MANE Select	c.1824G>T	p.Leu608Leu	synonymous	Exon 18 of 31	ENSP00000360822.2
	KCNT1	ENST00000460750.5	TSL:1	n.*1434G>T		non_coding_transcript_exon	Exon 18 of 32	ENSP00000418777.1
	KCNT1	ENST00000460750.5	TSL:1	n.*1434G>T		3_prime_UTR	Exon 18 of 32	ENSP00000418777.1

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD2 exomes AF: 0.00000419 AC: 1 AN: 238696 AF XY: 0.00000772

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 6.87e-7 AC: 1 AN: 1456186 Hom.: 0 Cov.: 33 AF XY: 0.00000138 AC XY: 1 AN XY: 723858

African (AFR) AF: 0.00 AC: 0 AN: 33400

American (AMR) AF: 0.00 AC: 0 AN: 43964

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25990

East Asian (EAS) AF: 0.00 AC: 0 AN: 39494

South Asian (SAS) AF: 0.0000117 AC: 1 AN: 85228

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 52798

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5762

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 1109380

Other (OTH) AF: 0.00 AC: 0 AN: 60170

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.49
CADD	Benign	6.4
DANN	Benign	0.79
PhyloP100		3.1

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: rs764141661; hg19: chr9-138662757;