Forme Fruste Variant of Rett Syndrome

Rett syndrome is a neurodevelopmental disorder that affects girls almost exclusively. A mutation in the MECP2 gene usually causes Rett syndrome, but in some cases, other genes may be involved.

Based on the genetic mutation that causes the condition and the symptoms reported, Rett syndrome is classified into classic and atypical types. About 32% of patients have the atypical form of the disease in which some symptoms are present, but they do not fulfill all the diagnostic criteria.

Forme fruste variant is one type of atypical Rett syndrome. It is an incomplete and milder manifestation of Rett syndrome. Symptom onset is reported in early childhood, and the progression is slower and more prolonged compared to classic Rett syndrome.


The early clinical manifestations of the forme fruste variant vary considerably but usually are mild. Most affected individuals retain the use of their hands. Other motor skills usually are preserved for an extended time and tend to regress much later in the course of the disease.

In one case study, the patient lost learned speech within the first two years of birth but regained it as she grew older. At age 17, she maintained motor skills but had mild mental retardation and apraxia (the inability to perform familiar day-to-day movements).

According to research, the head circumference of forme fruste Rett syndrome patients is within normal limits, albeit below average. Head growth may or may not decline during the course of the disease.

Other symptoms of the forme fruste variant include hand clapping, seizure activity, and teeth clenching or grinding.


The diagnosis of the forme fruste variant requires recognizing the subtle signs of Rett syndrome. But early symptoms are mild and can be easily missed, though patients may regress as they grow older. Identifying the subtle symptoms early and confirming the diagnosis with genetic testing can help better manage the condition.


Treatments for all forms of Rett syndrome, including the forme fruste variant, focus on the management of symptoms, relieving pain, and improving patients’ quality of life.

In addition to medications, targeted therapy for symptoms such as loss of speech and motor skills can be useful.

Patient’s communication skills, including speaking, may be improved with speech therapy.

Physiotherapy and exercise may help strengthen muscles, improve balance, hand movements, and walking skills. Similarly, occupational therapy can retrain patients to use their hands and legs for day-to-day use.

Aids and assistive devices can help the patient perform their daily activities independently and improve quality of life.


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