The E173A, R90P, and E150A mutations produced abnormally large displacement of tropomyosin to the inner domains of actin and an increase in the number of myosin heads in strong-binding state at low and high Ca<sup>2+</sup>, which is characteristic of CFTD.
Indeed, charge neutralization of D292 is connected to muscle hypotonia in individuals with D292Vactin mutations and linked to congenital fiber-type disproportion.
We raise the possibility that the presence or absence of structural disorganization when mutant actin incorporates into sarcomeres may be an important determinant of whether the histological patterns of CFTD or NM develop in ACTA1 myopathy.
We report three heterozygous missense mutations of the skeletal muscle alpha actin gene (ACTA1) in three unrelated cases of congenital fiber type disproportion (CFTD) from Japan and Australia.