5-170378901-A-T

Variant summary

Our verdict is Uncertain significance. Variant got 4 ACMG points: 4P and 0B. PM2 PP3_Moderate

The NM_004137.4(KCNMB1):c.379T>A(p.Phe127Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.00000479 in 1,461,876 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★).

• Frequency:
  • Genomes: not found (cov: 33)
  • Exomes 𝑓: 0.0000048 (0 hom.)
• Consequence: KCNMB1 NM_004137.4 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 3.32

Genes affected

KCNMB1 (HGNC:6285): (potassium calcium-activated channel subfamily M regulatory beta subunit 1) MaxiK channels are large conductance, voltage and calcium-sensitive potassium channels which are fundamental to the control of smooth muscle tone and neuronal excitability. MaxiK channels can be formed by 2 subunits: the pore-forming alpha subunit and the product of this gene, the modulatory beta subunit. Intracellular calcium regulates the physical association between the alpha and beta subunits. [provided by RefSeq, Jul 2008]

KCNIP1 (HGNC:15521): (potassium voltage-gated channel interacting protein 1) This gene encodes a member of the family of cytosolic voltage-gated potassium (Kv) channel-interacting proteins (KCNIPs), which belong to the neuronal calcium sensor (NCS) family of the calcium binding EF-hand proteins. They associate with Kv4 alpha subunits to form native Kv4 channel complexes. The encoded protein may regulate rapidly inactivating (A-type) currents, and hence neuronal membrane excitability, in response to changes in the concentration of intracellular calcium. Alternative splicing results in multiple transcript variants encoding different isoforms. [provided by RefSeq, May 2013]

ACMG classification

Verdict is Uncertain_significance. Variant got 4 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.933

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
KCNMB1	NM_004137.4	c.379T>A	p.Phe127Ile	missense_variant	4/4	ENST00000274629.9
KCNIP1	NM_001034838.3	c.88+24937A>T		intron_variant
KCNIP1	XM_017009407.2	c.88+24937A>T		intron_variant
KCNIP1	XM_017009408.2	c.88+24937A>T		intron_variant

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
KCNMB1	ENST00000274629.9	c.379T>A	p.Phe127Ile	missense_variant	4/4	1	NM_004137.4	P1
KCNIP1	ENST00000377360.8	c.88+24937A>T		intron_variant		1		P4
KCNIP1	ENST00000517344.1	c.88+24937A>T		intron_variant, NMD_transcript_variant		3
KCNIP1	ENST00000518527.1	n.478+24937A>T		intron_variant, non_coding_transcript_variant		4

Frequencies

GnomAD3 genomes Cov.: 33

GnomAD3 exomes AF: 0.0000239 AC: 6 AN: 250952 Hom.: 0 AF XY: 0.0000147 AC XY: 2 AN XY: 135676

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.000173

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad SAS 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: 0.00000479 AC: 7 AN: 1461876 Hom.: 0 Cov.: 32 AF XY: 0.00000413 AC XY: 3 AN XY: 727242

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.000157

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: 0.00

Gnomad4 OTH exome AF: 0.00

GnomAD4 genome Cov.: 33

Bravo AF: 0.0000378

ExAC AF: 0.0000165 AC: 2

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Ambry Genetics

Nov 12, 2021

The c.379T>A (p.F127I) alteration is located in exon 4 (coding exon 3) of the KCNMB1 gene. This alteration results from a T to A substitution at nucleotide position 379, causing the phenylalanine (F) at amino acid position 127 to be replaced by an isoleucine (I). Based on insufficient or conflicting evidence, the clinical significance of this alteration remains unclear. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.32
BayesDel_addAF	Benign	-0.34	T
BayesDel_noAF	Benign	-0.46
Cadd	Benign	20
Dann	Uncertain	0.99
DEOGEN2	Benign	0.30	T
Eigen	Benign	0.081
Eigen_PC	Benign	-0.077
FATHMM_MKL	Uncertain	0.81	D
LIST_S2	Benign	0.57	T
M_CAP	Benign	0.021	T
MetaRNN	Pathogenic	0.93	D
MetaSVM	Benign	-1.2	T
MutationAssessor	Uncertain	2.6	M
MutationTaster	Benign	1.0	D;D
PrimateAI	Uncertain	0.48	T
PROVEAN	Uncertain	-2.6	D
REVEL	Benign	0.27
Sift	Uncertain	0.0080	D
Sift4G	Pathogenic	0.0	D
Polyphen		0.99	D
Vest4		0.42
MutPred		0.92		Loss of methylation at K126 (P = 0.0749);
MVP		0.24
MPC		0.29
ClinPred		0.45	T
GERP RS		2.9
Varity_R		0.26
gMVP		0.55

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

Publications

LitVar

Other links and lift over

dbSNP: rs754879970; hg19: chr5-169805905;