familial periodic paralysis (hyperkalemic, normokalemic, hypokalemic, HYPP, NKPP, HYPOPP)

Genetics

• autosomal dominant
• associated with defect in SCN4A, Na+ channel alpha subunit
• associated with defects in CACNA1S; substitution of highly conserved Arg in the S4 segment of CACNA1S with His or Gly
• associated with defects in KCNE3

Clinical manifestations

• onset before 20 years of age
• episodic flaccid generalized muscle weakness
• intermittent muscular paralysis of the shoulder & pelvic girdle, other regions involved later in the course of the disease
• slow, progressive weakness
• no muscle weakness between attacks
• absent deep tendon reflexes (DTR)
• headaches
• thirst
• lethargy

Laboratory

• serum K+ (low, HYPOPP; high HYPP; normal NKPP) during attacks
• CACNA1S gene mutation

More general terms

• genetic disease of muscle (inherited myopathy)
• periodic paralysis
• genetic syndrome (multisystem disorder)

Additional terms

• paramyotonia congenita of von Eulenburg (PMC)
• thyrotoxic hypokalemic periodic paralysis

Patient information

familial periodic paralysis patient information

Database

• OMIM: https://mirror.omim.org/entry/170400
• OMIM: https://mirror.omim.org/entry/170500
• OMIM: https://mirror.omim.org/entry/603967
• OMIM: https://mirror.omim.org/entry/170400