The mortality rate in Rett syndrome is 1.2% per annum, 48% of deaths o
ccurring in debilitated people, 13% from natural causes, 13% with prio
r severe seizures and 26% sudden and unexpected. Respiratory dysrhythm
ias were usually present. Neuropathology confirmed reductions in corti
cal dendrites and in one case immaturity of cardiac conducting tissues
.