9-135786406-C-T

Variant names:

• chr9-135786406-C-T
• rs372410150
• NM_020822.3:c.3387C>T

Variant summary

Our verdict is Benign. The variant received -21 ACMG points: 0P and 21B. BP4_Strong BP6_Very_Strong BP7 BS1 BS2

The NM_020822.3(KCNT1):​c.3387C>T​(p.Ala1129Ala) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000812 in 1,576,410 control chromosomes in the GnomAD database, including 1 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★). Synonymous variant affecting the same amino acid position (i.e. A1129A) has been classified as Likely benign.

• Frequency:
  • Genomes: 𝑓 0.00014 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000075 (1 hom.)
• Consequence: KCNT1 NM_020822.3 synonymous
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:6
• Conservation: PhyloP100: -3.41
• 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: Benign. The variant received -21 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.72).
• BP6: Variant 9-135786406-C-T is Benign according to our data. Variant chr9-135786406-C-T is described in ClinVar as Benign/Likely_benign. ClinVar VariationId is 473389.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BP7: Synonymous conserved (PhyloP=-3.41 with no splicing effect.
• BS1: Variant frequency is greater than expected in population eas. GnomAd4 allele frequency = 0.000138 (21/152314) while in subpopulation EAS AF = 0.00271 (14/5172). AF 95% confidence interval is 0.00164. There are 0 homozygotes in GnomAd4. There are 8 alleles in the male GnomAd4 subpopulation. Median coverage is 33. This position passed quality control check.
• BS2: High AC in GnomAd4 at 21 AD gene.

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.3387C>T	p.Ala1129Ala	synonymous	Exon 29 of 31	NP_065873.2	Q5JUK3-3
	KCNT1	NM_001272003.2		c.3252C>T	p.Ala1084Ala	synonymous	Exon 28 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.3387C>T	p.Ala1129Ala	synonymous	Exon 29 of 31	ENSP00000360822.2	Q5JUK3-3
	KCNT1	ENST00000460750.5	TSL:1	n.*2997C>T		non_coding_transcript_exon	Exon 29 of 32	ENSP00000418777.1	F8WC49
	KCNT1	ENST00000460750.5	TSL:1	n.*2997C>T		3_prime_UTR	Exon 29 of 32	ENSP00000418777.1	F8WC49

Frequencies

GnomAD3 genomes AF: 0.000138 AC: 21 AN: 152198 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.0000965

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.00270

Gnomad SAS AF: 0.000621

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.00

Gnomad OTH AF: 0.00

GnomAD2 exomes AF: 0.000268 AC: 47 AN: 175690 AF XY: 0.000247

Gnomad AFR exome AF: 0.000114

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00270

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.000212

GnomAD4 exome AF: 0.0000751 AC: 107 AN: 1424096 Hom.: 1 Cov.: 36 AF XY: 0.0000836 AC XY: 59 AN XY: 705374

African (AFR) AF: 0.00 AC: 0 AN: 32606

American (AMR) AF: 0.00 AC: 0 AN: 39650

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 25514

East Asian (EAS) AF: 0.00146 AC: 55 AN: 37660

South Asian (SAS) AF: 0.000436 AC: 36 AN: 82490

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 48804

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 4766

European-Non Finnish (NFE) AF: 0.00000366 AC: 4 AN: 1093774

Other (OTH) AF: 0.000204 AC: 12 AN: 58832

GnomAD4 genome AF: 0.000138 AC: 21 AN: 152314 Hom.: 0 Cov.: 33 AF XY: 0.000107 AC XY: 8 AN XY: 74482

African (AFR) AF: 0.0000962 AC: 4 AN: 41582

American (AMR) AF: 0.00 AC: 0 AN: 15310

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 3472

East Asian (EAS) AF: 0.00271 AC: 14 AN: 5172

South Asian (SAS) AF: 0.000621 AC: 3 AN: 4830

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 10626

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 292

European-Non Finnish (NFE) AF: 0.00 AC: 0 AN: 68004

Other (OTH) AF: 0.00 AC: 0 AN: 2114

Alfa AF: 0.00 Hom.: 0

Bravo AF: 0.0000756

ClinVar

ClinVar submissions as Germline

Significance: Benign/Likely benign

Revision: criteria provided, multiple submitters, no conflicts

Pathogenic	VUS	Benign	Condition
-	-	2	not provided (2)
-	-	1	Autosomal dominant nocturnal frontal lobe epilepsy 5 (1)
-	-	1	Developmental and epileptic encephalopathy, 14 (1)
-	-	1	Developmental and epileptic encephalopathy, 14;C3554306:Autosomal dominant nocturnal frontal lobe epilepsy 5 (1)
-	-	1	KCNT1-related disorder (1)

Computational scores

Source: dbNSFP v4.9

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.72
CADD	Benign	2.9
DANN	Benign	0.64
PhyloP100		-3.4
Mutation Taster		=100/0	polymorphism

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: rs372410150; hg19: chr9-138678252; COSMIC: COSV53714717; COSMIC: COSV53714717;