We compared electrophysiological findings, cerebrospinal fluid neurochemistry, and 13 clinical characteristics between patients carrying missense mutations and those carrying truncating mutations. Nonrandom XCI was associated with milder phenotypes, including a mitigated classic RTT caused by a rare early truncating mutation. Patients with truncating mutations have a higher incidence of awake respiratory dysfunction and lower levels of cerebrospinal fluid homovanillic acid.
Scoliosis is more common in patients with missense mutations.