Rett syndrome is a severe
neurodevelopmental disorder of unknown etiology, occurring almost exclusively in female patients. The etiology and functional significance of plasma
carnitine deficiency seen in some patients with
Rett syndrome is unknown. To investigate whether
L-carnitine might be of benefit in
Rett syndrome, a randomized, placebo-controlled, double-blind crossover trial of
L-carnitine has been completed in 35 subjects. Eight-week treatment phases were completed for both a placebo and
L-carnitine. Outcome was measured by parents/caregivers and at medical follow-up using three established tools: the
Rett Syndrome Motor Behavioral Assessment, the Hand
Apraxia Scale, and the Patient Well-Being Index. Analysis comparing change between baseline and week 8 of treatment for
L-carnitine and the placebo showed that both parents/caregivers and medical follow-up detected improvements in the subjects' well-being. In addition, medical review showed an improvement on the Hand
Apraxia Scale for a higher proportion of girls on
L-carnitine. Identification of predictors of clinical improvement has been limited by the power of the study. These findings suggest that
L-carnitine is of benefit in some patients with
Rett syndrome. While
L-carnitine did not lead to major functional changes in ability, the type of changes reported could still have a substantial impact on the girls and their families. Information is still needed, however, to determine if only subgroups of girls with the disorder are responsive to
L-carnitine and the appropriate
duration of therapy.