Results
Study Participants: 11 female and 14 male children, mean age 8.2 years old, were enrolled in the study. Of those enrolled, 21 participants were confirmed to have a maternal deletion (the number of deleted bases was variable) and 4 were positive for a mutation of the UBE3A gene. Twenty-four children completed the 16-week open-label study; one participant withdrew at week 16 due to unrelated seizure activity.
Primary Outcome Measure
A significant improvement in raw scores of the communication subscale of Bayley-III (Table 2) was observed at T3 when compared to baseline, F(2,46) = 3.72, p < 0.05. Post hoc analysis revealed scores from participants between the ages of 4 and 9 years old were responsible for a 40% increase, while scores from participants between ages 9 and 12 years of age remained unchanged. Moreover, a significant improvement, F(2,46) = 5.011, p < 0.05, of the subscale self-direction was observed at both T2 and T3, compared to T1. While no change was observed in gross motor ability, a significant increase (15%) in the measure of fine motor ability was observed at T3, F(2,46) = 3.28, p < 0.05.
Neuropsychological Outcomes
A significant improvement in the raw scores of the receptive communication index of the Vineland-II was found between T2 and baseline, F(2,46) = 6.73, p < 0.05. Two domains of the PLS-IV, auditory comprehension and total language ability, were both found to have increased significantly when measures at T3 were compared to baseline, F(2,44) = 6.73, p <0.05 and F(2,44) = 5.84, p <0.05, respectively.
Clinical Outcomes
Blood screening tests showed no clinically significant changes over the 16-week study course and no serious adverse effects related to minocycline treatment were reported (Table 1). In 3 cases, caregivers reported lethargy and/or dizziness that required a dose adjustment and was considered related to the minocycline treatment. All of these participants were receiving 100 mg of minocycline BID. In 2 other cases, caregivers reported difficultly standing and/or walking that resolved after the discontinuation of minocycline. Significant clinical improvement over baseline, for all participants, as measured by the CGI-S score (Table 3), was observed at T2 and T3 [F(2, 46) =13.20, p < 0.05]. Analysis of EEG scores revealed a 4.3% and 10.8% improvement when T2 and T3 observations were compared to baseline but did not reach the level of significance [F(2,46) = 1.494, p > 0.05]. For both measures, calculated partial η was equal to 0.05, an indication of a moderate effect size.