Potassium Channel, Calcium-Activated, Large Conductance, Subfamily M, Alpha Member 1

Alternative Names

  • KCNMA1
  • Slowpoke, Drosophila, Homolog of
  • SLO
  • SLO1
  • SLO-Alpha
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OMIM Number

600150

NCBI Gene ID

3778

Uniprot ID

Q12791

Length

768,207 bases

No. of Exons

45

No. of isoforms

7

Protein Name

Calcium-activated potassium channel subunit alpha-1

Molecular Mass

137560 Da

Amino Acid Count

1236

Genomic Location

chr10:76,869,602-77,637,808

Gene Map Locus
10q22.3

Description

The KCNMA1 gene encodes the pore-forming alpha subunit of the voltage-gated potassium channel.  This channel can be activated by both membrane depolarization as well as by intracellular calcium ions and it allows strong conductance of potassium ions through cell membranes.  By carrying out this function, the potassium channel is responsible for the regulation of smooth muscle contraction and the apoptotic process as well as the response to osmotic stress, hypoxia and carbon monoxide. 

The KCNMA1 gene is associated with Generalized Epilepsy and Paroxysmal Dyskinesia (GEPD), an autosomal dominant disorder characterized by epileptic seizures, paroxysmal nonkinesigenic dyskinesia and developmental delay.

Epidemiology in the Arab World

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Other Reports

Saudi Arabia

Tabarki et al. (2016) described two sisters suffering from severe developmental delay, myoclonic seizures, diffuse hypotonia and severe cerebellar atrophy starting from the age of 8 months.  The patients were born to healthy second-cousin parents.  A combined exome/autozygome analysis uncovered a novel homozygous frameshift duplication (c.2026dupT, p.Tyr676Leufs*7) in the KCNMA1 gene of both patients.  The parents were heterozygous for the mutation.  The mutation was also not found in 1500 Saudi exomes and was scored as pathogenic based on ACMG guidelines.  The authors suggested this to be a new autosomal recessive, loss-of-function phenotype distinct from the previously reported autosomal dominant, gain-of-function GEPD phenotype associated with KCNMA1 mutations.

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