103 Rett’s Disorder (299.80)

Introduction

• First discovered in 1966 by an Austrian physician (Harris, Glasberg, & Ricca).
  • Noticed two girls in his waiting room exhibiting identical hand mannerism.
  • Ultimately, he identified similar hand movements among 20 other girls diagnosed with mental retardation.
• Characteristically defined as a pattern of regression beginning at 5-18 months old to include social, language, motor, and cognitive development (Hoffman, 2009).
• Rett’s disorder is second to Down’s syndrome as a cause of mental retardation in females (Hoffman, 2009).
  • Characteristically, only found in females due to being linked with the X chromosome that encodes Methyl-CpG binding protein-2 (MECP2).
    • MECP2 involved in the regulation of expression of other genes during development.
    • Mutations in MECP2 reported in 87% of females with classical Rett’s disorder
    • Mutations in MECP2 reported in 50% of females with variant of the disorder
    • Mutations in MECP2 found to be lethal in males.

DSM-IV-TR criteria

• A. All of the following:
  • 1. apparently normal prenatal and perinatal development
  • 2. apparently normal psychomotor development through the first 5 months after birth
  • 3. normal head circumference
• B. Onset of all of the following after the period of normal development:
  • 1. deceleration of head growth between ages 5 months and 48 months
  • 2. loss of previously acquired purposeful hand skills between ages 5 and 30 months with the subsequent development of stereotyped hand movements (e.g., hand wringing or hand washing)
  • 3. loss of social engagement early in the course (although often social interaction develops later)
  • 4. appearance of poorly coordinated gait or trunk movements
  • 5. severely impaired expressive and receptive language development with severe psychomotor retardation

Associated features

Children diagnosed with Rett’s Disorder present normal development and functioning until onset between 5 and 48 months. Rett’s Disorder has typically been associated with Severe or Profound Mental Retardation. There may be an increased frequency of EEG abnormalities in this particular population of individuals. Also, seizure disorder is seen in individuals with Rett’s Disorder. Research suggests that the cause of Rett’s Disorder may be a genetic mutation. Rett’s Disorder is a genetic disorder of developmental arrest or failure of brain maturation. This is thought to happen when subsets of neurons and their synapses are disrupted during a very important time of brain development. This deviation occurs at the end of pregnancy or in the first few months of life during the important time of synapse development. A deceleration of head growth between ages 5 and 48 months is one symptom. Others are loss of previously acquired purposeful hand skills between ages 5 and 30 months, loss of social engagement early on, appearance of poorly coordinated gait movement, severely impaired expressive and receptive language development with severe psychomotor retardation. Rett’s Disorder is not a degenerative disorder. It is a neurodevelopmental disorder. As long as the patient does not fall ill or suffer from complications, survival into adulthood is expected.

There are four different stages of the disorder:

• Early Onset occurs at about 6 to 18 months. The symptoms are vague and often overlooked. There are gross motor delays and less eye contact and loss of interest in toys. This stage can last for up to a year.
• Rapid Destructive stage occurs between 1 and 4 years old. Hand skills and spoken language skill are lost. It can last from a few weeks to a couple of years. Autistic-like symptoms can also occur.
• Plateau is the third stage. It is between ages 2 and 10. Motor problems and seizures are characteristic at this stage. Most girls stay at this stage during the rest of their lives. They show more interest in their surroundings.
• Late Motor Deterioration is the final stage. Reduced mobility is the most prominent feature. Girls who could walk may now not be able to walk. Cognitive abilities stay the same. This can last for years as well.

Child vs. adult development

• Although the duration of Rett’s Disorder is lifelong, the onset is typically before the age of four and most often in the child’s first or second year.
• Symptoms of Rett’s Disorder are present in both children and adults with this disorder.
  • Progressive loss of skills is typically seen throughout the affected individual’s lives.

Epidemiology

Other than two cases of boys being diagnosed with this disease, Rett’s Disorder only affects females and is much less common than Autistic Disorder. It is found in all races and ethnic groups of the world.

70-80% of females diagnosed with this disorder have the MECP2 genetic mutation. The rest of the cases are believed to have partial gene mutation.

Onset usually occurs before four years of age, usually about the first or second year. The duration is lifelong, and the loss of skills persistent and progressive. Recovery is usually quite limited, although some developmental gains may be made and there may be interest in social interaction as during late childhood or adolescence. Difficulties with communication and behavior remain constant throughout life.

Etiology

This disease is caused by a genetic mutation on the long arm of the X chromosome. These genes cause the brain to develop incorrectly by inappropriately activating other genes in the brain at the wrong time.

Empirically supported treatments

There is currently no cure for Rett’s Disorder but treatment is available to alleviate the symptoms.

There are treatments available to manage their symptoms such as physical therapy or occupational therapy. Some find that medications for muscular rigidity are helpful while others gain normalcy from medications that treat things like anxiety or irritability. A child psychiatrist should be consulted for proper medication.

While there is no cure, however, there are several treatments options. Treatment is therefore concentrated on relief of individual symptoms, compensation for physical disabilities and the provision of the best possible stimulation and quality of life. Deformities and progressive disabilities should be prevented wherever possible. Occupational therapy (in which therapists help children develop skills needed for performing self-directed activities – occupations – such as dressing, feeding, and practicing arts and crafts), physiotherapy, and hydrotherapy may prolong mobility. Treatment must always be individually structured, on the basis of the specific problem complex and point of departure of each girl, who must be offered help in utilizing her retained abilities and stimulation for further development. Special academic, social, vocational, and support services may also be required in some cases.

It has been proposed that this disorder not be included in DSM-5. The rationale is that Rett’s Disorder patients often have autistic symptoms for only a brief period during early childhood, so inclusion in the autism spectrum is not appropriate for most individuals.