Recently (2008), it was shown that the conditional deletion of Mecp2 in catecholaminergic neurons (by crossing of Th-Cre mice with loxP-flanked Mecp2 ones) recapitulates a motor symptomatology, it was further documented that brain levels of Th in mice lacking MeCP2 in catecholaminergic neurons only are reduced, participating to the motor phenotype.However, the most studied model for the evaluation of therapeutics is the Mecp2-null mouse (totally devoid of MeCP2). In this context, a reduction in the number and soma size of Th-expressing neurons is present from 5 weeks of age and is accompanied by a decrease of Th immunoreactivity in the caudate-putamen, the principal target of dopaminergic neurons arising from the SNpc. Moreover, a neurochemical analysis of dopaminergic contents in microdissected midbrain and striatal areas revealed a reduction of dopamine at five and nine weeks of age. It is noteworthy that later on (at nine weeks), the morphological parameters remain altered but not worsen, whereas the phenotype progresses and behavioral deficits are more severe. The amount of fully activated Th (Serine40-phosphorylated isoform) in neurons that remain in the SNpc is mildly affected at 5 weeks but severely impaired by 9 weeks. Finally, using a chronic and oral L-Dopa treatment on MeCP2-deficient mice authors reported an amelioration of some of the motor deficits previously identified. Altogether, these results argue for an alteration of the nigrostriatal dopaminergic pathway in MeCP2-deficient animals as a contributor of the neuromotor deficits.There is an association of the disease with brain-derived neurotrophic factor (BDNF).
The incidence of Rett syndrome in males is unknown, partly owing to the low survival of male fetuses with the Rett syndrome-associated MECP2 mutations, and partly to differences between signs caused by MECP2 mutations and those caused by Retts.Females can live up to 40 years or more. Laboratory studies on Rett syndrome may show abnormalities such as:

EEG abnormalities from 2 years of age
atypical brain glycolipids
elevated CSF levels of beta-endorphin and glutamate
reduction of substance P
decreased levels of CSF nerve growth factorsA high proportion of deaths are abrupt, but most have no identifiable cause; in some instances death is the result most likely of:

spontaneous brainstem dysfunction
cardiac arrest, likely due to long QT syndrome, ventricular tachycardia or other arrhythmias
seizures
gastric perforation

History
Andreas Rett, a pediatrician in Vienna, first described the condition in 1966. As his writings were in German, they did not become widely known in the English-speaking world. Bengt Hagberg, a Swedish pediatrician, published an English article in 1983 and named the condition after Rett. In 1999, Lebanese-American physician Huda Zoghbi discovered the mutation that causes the condition. Research
Gene therapy is under study in animal models to achieve regulated expression of a normal MECP2 gene. In March 2022, Taysha Gene Therapies announced that they had received Clinical Trial Application (CTA) approval from Health Canada for a clinical trial of their investigational gene therapy for adult females with Rett Syndrome. In fiction
In August 2021, a novel by British author Victoria Scott, Patience, was published by Head of Zeus.