Rett Syndrome, Rett Syndrome

Scoliosis, growth failure, and constipation are very common and can be problematic. Many argue that it is misclassified as a pervasive developmental disorder, just as it would be to include such disorders as fragile X syndrome, tuberous sclerosis, or Down syndrome where one can see autistic features. "Is Rett Syndrome a Subtype of Pervasive Developmental Disorders" Tsai, L.Y., Journal of Autism and Developmental Disorders The symptoms of this disorder are most easily confused with those of Angelman syndrome, cerebral palsy and autism.

An atypical form of Rett syndrome, characterized by infantile spasms or early onset epilepsy, can also be caused by a mutation to the gene encoding cyclin-dependent kinase-like 5 (CDKL5). Rett syndrome affects one in every 12,500 female live births by age 12 years.

Because the disease-causing gene is located on the X chromosome, a female born with a MECP2 mutation on her X chromosome has another X chromosome with an ostensibly normal copy of the same gene, while a male with the mutation on his X chromosome has no other X chromosome, only a Y chromosome; thus, he has no normal gene. Without a normal gene to provide normal proteins in addition to the abnormal proteins caused by a MECP2 mutation, the XY karyotype male fetus is unable to check the development of the disease, hence the failure of many male fetuses with a MECP2 mutation to survive to term. Females with a MECP2 mutation, however, have a non-mutant chromosome that provides them enough normal protein to survive at least to birth. Research shows that males with Rett syndrome almost all have Klinefelter's syndrome as well (in which the male has an XXY karyotype). Schwartzman, J.S., et al. Rett Syndrome in a Boy with 47,XXY Karyotype Confirmed by a Rare Mutation on the MECP2 Gene. 2001. Neuropediatrics 32:162-164 Thus, a non-mutant MECP2 gene is necessary for a Rett's-affected embryo to survive in most cases, and the embryo, male or female, must have another X chromosome.

However, if most cells in the brain activate the X chromosome with the functional MECP2 allele, the individual will have very mild Rett syndrome; likewise, if most neurons activate the X chromosome with the mutated MECP2 allele, the individual will have very severe Rett syndrome just as males with MECP2 mutations do (as they only have one X chromosome).

The brief period of developmental progress is followed by stagnation and regression of previously acquired skills. During regression some features are similar to those of autism. It is, hence, easy to mistakenly diagnose Rett syndrome for autism.

His niece had been diagnosed with Rett Syndrome and died at the age of 16.

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