Autosomal recessive Pseudohypoaldosteronism Type I (arPHA1) is caused by mutations to the epithelial sodium channel (ENaC). The condition may be confused with cystic fibrosis.
Inheritance: autosomal recessive
Gene affected: alpha , beta or gamma subunits of the ENaC
Gene Map Locus
Gene
12p13
SCCN1 A (alpha)
16p12.2-p12.1
SCCN1 B (beta)
16p12
SCCN1 G (gamma)
SCCN = sodium channel, nonvoltage-gated 1
Clinical features:
(1) lifelong renal salt-wasting starting at birth
(2) volume depletion
(3) failure to thrive
(4) short stature
(5) vomiting
(6) clinical improvement with a high salt diet
(7) condition persists into adulthood
(8) usually requires therapy with potassium binding resins to control hyperkalemia
Laboratory findings:
(1) hyponatremia
(2) hyperkalemia
(3) metabolic acidosis
(4) elevated plasma levels of aldosterone
(5) increased sodium levels in colon mucus, sweat and saliva
See also bronchiectasis with or without elevated sweat chloride (BESC, above).
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