Mutations in subunits of the epithelial sodium channel (ENaC) can result in a hereditary syndrome that resembles cystic fibrosis in some of its features. This is referred to as Bronchiectasis with or without elevated sweat chloride (BESC).
SCCN = sodium channel, nonvoltage-gated 1
SCNN1 consists of 3 subunits - A, B and G.
Subunit
Location
Mutation
SCNN1A
12p13
BESC2
SCNN1B
16p12
BESC1
SCNN1G
16p12
BESC3
Features of BESC:
(1) bronchiectasis without progressive decline in lung function
(2) variable elevation in sweat chloride
(3) normal pancreatic exocrine function
(4) absence of CFTR mutations
(5) absence of other phenotypic features of cystic fibrosis (normal vasa deferentia in males, etc)
Mutations in SCCN1 can also result in autosomal recessive pseudohypoaldosteronism type 1 (see section 13.19.10, below)
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