9-135750150-C-T

Variant names:

• chr9-135750150-C-T
• NM_020822.3:c.307C>T
• KCNT1 p.Leu103Leu

Variant summary

Our verdict is Uncertain significance. The variant received 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_020822.3(KCNT1):​c.307C>T​(p.Leu103Leu) variant causes a synonymous change. The variant allele was found at a frequency of 0.000000684 in 1,461,584 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. L103L) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 6.8e-7 (0 hom.)
• Consequence: KCNT1 NM_020822.3 synonymous
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 3.92
• Publications: 0 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: Ambry Genetics, G2P, Labcorp Genetics (formerly Invitae)
• 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: Uncertain_significance. The variant received 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.37).

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

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNT1	NM_020822.3	MANE Select	c.307C>T	p.Leu103Leu	synonymous	Exon 3 of 31	NP_065873.2	Q5JUK3-3
	KCNT1	NM_001272003.2		c.163C>T	p.Leu55Leu	synonymous	Exon 2 of 31	NP_001258932.1	Q5JUK3-4

Ensembl Transcripts

Sel.	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	KCNT1	ENST00000371757.7	TSL:1 MANE Select	c.307C>T	p.Leu103Leu	synonymous	Exon 3 of 31	ENSP00000360822.2	Q5JUK3-3
	KCNT1	ENST00000460750.5	TSL:1	n.307C>T		non_coding_transcript_exon	Exon 3 of 32	ENSP00000418777.1	F8WC49
	KCNT1	ENST00000487664.5	TSL:5	c.307C>T	p.Leu103Leu	synonymous	Exon 3 of 32	ENSP00000417851.2	Q5JUK3-2

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 6.84e-7 AC: 1 AN: 1461584 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727080

African (AFR) AF: 0.00 AC: 0 AN: 33478

American (AMR) AF: 0.00 AC: 0 AN: 44716

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26134

East Asian (EAS) AF: 0.00 AC: 0 AN: 39700

South Asian (SAS) AF: 0.00 AC: 0 AN: 86256

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53218

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

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111938

Other (OTH) AF: 0.00 AC: 0 AN: 60378

GnomAD4 genome Cov.: 32

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.37
CADD	Benign	12
DANN	Benign	0.81
PhyloP100		3.9

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

MaxEntScan Visualizer can be used to analyze the impact of this mutation on the neighboring sequence.

Other links and lift over

hg19: chr9-138641996;