Unstable DNA in a patient with a severe form of congenital myotonic dystrophy

Recently, an unstable DNA (expanded CTG repeat) was identified as the mutation that causes myotonic dystrophy (DM). By Southern blot analysis of DNA derived from peripheral blood, patients with congenital form of DM are shown to have greater expansion of DM specific band than is seen in the analyses of adult form of DM. We present here tissue expression of unstable DNA in an autopsied case of severe congenital form of DM. Our study revealed the largest expanding band of 19 kb was uniformly seen in various tissues from an autopsied infant with congenital form of DM.