Fig. 1.

The family pedigree: The five individuals with MECP2 mutations are depicted in this three generation pedigree. The female in generation I represented by the bulls-eye has cognitive delay and lacks the clinical features of RTT; the female in generation II represented by the checkerboard pattern has cognitive delay and aberrant behavior and lacks the clinical features of RTT; the female in generation III represented by the vertical stripes has typical features of RTT; and both males have cognitive delay and a pattern of progressive motor impairments that do not reflect the clinical features of RTT