A positive test for the MECP2 mutation is not enough to make a diagnosis.Ruling in
Decreased or loss of use of fine motor skills
Decreased or loss of verbal speech
Abnormalities during gait
Repetitive hand movements such as wringing/squeezing or clapping/tappingRuling out
Traumatic or anoxic/hypoxic brain injury, neurometabolic disease, or severe infection that may better explain symptoms
Abnormal psychomotor development during the first six months of lifeSupportive criteria
Breathing disturbances when awake
Bruxism while awake
Impaired sleep pattern
Abnormal muscle tone
Peripheral vasomotor disturbances
Scoliosis/kyphosis
Growth retardation
Small cold hands and feet
Inappropriate laughing/screaming spells
Diminished response to pain
Intense eye communication (eye pointing)

Differential diagnosis
Signs of Rett syndrome that are similar to autism:

Signs of Rett syndrome that are also present in cerebral palsy (regression of the type seen in Rett syndrome would be unusual in cerebral palsy; this confusion could rarely be made):

Treatment
Currently there is no cure for Rett syndrome. Treatment is directed towards improving function and addressing symptoms. A multi-disciplinary team approach is typically used to treat the person throughout life. This team may include primary care physician, physical therapist, occupational therapist, speech-language pathologist, nutritionist, and support services in academic and occupational settings. Some children may require special equipment and aids such as braces to arrest scoliosis, splints to modify hand movements, and nutritional programs to help them maintain adequate weight.Because of the increased risk of sudden cardiac death, when long QT syndrome is found on an annual screening EKG it is treated with an anti-arrhythmic such as a beta-blocker.
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.