Zappella variant is an atypical form of Rett syndrome. It was first described by Italian psychiatrist Michele Zappella, MD, and colleagues in 1992. It also is called the preserved speech variant because patients have better speech and hand use than patients with classic Rett syndrome.

Cause

Patients with the Zappella variant have mutations in the MECP2 gene, as do patients with classic Rett syndrome. These are either missense or nonsense mutations that cause loss of protein function. Missense mutations refer to a single letter change in the DNA sequence that causes one amino acid to be substituted with another amino acid in the protein sequence (amino acids are the building blocks of proteins).

In nonsense mutations, a single letter change in the DNA sequence introduces a stop signal that causes the protein to stop being made earlier than normal, resulting in a truncated protein with less or no activity. Nonsense mutations in classic Rett syndrome tend to occur at the beginning of the DNA sequence (early truncating mutations), whereas nonsense mutations in the Zappella type tend to occur toward the end of the gene (late truncating mutations). These differences partly explain the differences in the severity of the disease between classic Rett and the Zappella variant.

Symptoms

Zappella variant patients have milder symptoms compared to patients with classic Rett syndrome.

In most cases, the growth characteristics and head size of patients are normal.

Most patients show speech problems and stereotypic hand movements that are characteristic of the classic type but recover some degree of speech and hand use as they grow. Some patients show an intermittent mix of typical and atypical vocalizations from the first months of life onward. Speech abilities may range from single words to the ability to combine words. They also may be able to draw or write simple sentences.

Rarely, some patients may have progressive scoliosis (curvature of the spine), epileptic seizures, and breathing issues.

Nearly 76 percent of patients with the Zappella variant of Rett syndrome have autistic features that include poor communication and social interaction skills.

Obesity is a common feature in these patients.

Treatment options

Treatment is symptomatic and supportive.

Physical and occupational therapy may be needed constantly to improve body and hand movements, and to help carry out everyday activities such as dressing and eating. Hydrotherapy, aqua therapy, and hippotherapy may be beneficial for these patients.

Speech and language therapy and music therapy may help improve vocalization, communication, and cognitive skills.

A good diet rich in calcium is recommended to strengthen bones and reduce scoliosis. A diet high in fat and calories also may be recommended.

Braces and surgery may be required for scoliosis. Splints may be needed to improve hand movements.

Medications may be needed for breathing issues and to relieve constipation, indigestion, or gastric reflux disease

Anti-epileptic drugs such as sodium valproate, lamotrigine, and carbamazepine may be necessary to control seizures.

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