9-135759743-T-C

Variant names:

• chr9-135759743-T-C
• NM_020822.3:c.919T>C
• KCNT1 p.Phe307Leu

Variant summary

Our verdict is Uncertain significance. The variant received 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_020822.3(KCNT1):​c.919T>C​(p.Phe307Leu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. No clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar. Another nucleotide change resulting in the same amino acid substitution has been previously reported as Uncertain significance in ClinVar. Synonymous variant affecting the same amino acid position (i.e. F307F) has been classified as Likely benign.

• Frequency: Genomes: not found (cov: 33)
• Consequence: KCNT1 NM_020822.3 missense
• Clinical Significance: Not reported in ClinVar
• Conservation: PhyloP100: 7.73
• 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, Labcorp Genetics (formerly Invitae), 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: Uncertain_significance. The variant received 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.903

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.919T>C	p.Phe307Leu	missense	Exon 11 of 31	NP_065873.2	Q5JUK3-3
	KCNT1	NM_001272003.2		c.784T>C	p.Phe262Leu	missense	Exon 10 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.919T>C	p.Phe307Leu	missense	Exon 11 of 31	ENSP00000360822.2	Q5JUK3-3
	KCNT1	ENST00000460750.5	TSL:1	n.*529T>C		non_coding_transcript_exon	Exon 11 of 32	ENSP00000418777.1	F8WC49
	KCNT1	ENST00000460750.5	TSL:1	n.*529T>C		3_prime_UTR	Exon 11 of 32	ENSP00000418777.1	F8WC49

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 33

ClinVar

Not reported in ClinVar

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.31	D
BayesDel_noAF	Pathogenic	0.21
CADD	Pathogenic	30
DANN	Uncertain	1.0
DEOGEN2	Uncertain	0.62	D
Eigen	Pathogenic	0.74
Eigen_PC	Pathogenic	0.70
FATHMM_MKL	Uncertain	0.88	D
LIST_S2	Pathogenic	0.98	D
M_CAP	Uncertain	0.10	D
MetaRNN	Pathogenic	0.90	D
MetaSVM	Benign	-0.47	T
MutationAssessor	Uncertain	2.5	M
PhyloP100		7.7
PrimateAI	Pathogenic	0.82	D
PROVEAN	Pathogenic	-5.5	D
REVEL	Pathogenic	0.66
Sift	Uncertain	0.0020	D
Sift4G	Uncertain	0.0030	D
Varity_R		0.94
gMVP		0.99
Mutation Taster		=34/66	disease causing

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: chr9-138651589;