['Smith-Lemli-Opitz syndrome (SLOS) results in multiple malformations, growth deficiency, and mental retardation. Cholesterol supplementation has been used for several years to treat symptoms of SLOS. We assessed the developmental progress of children and adolescents with SLOS over a 6-year period.', 'Patients with SLOS (n=14) received continuous cholesterol supplementation as part of a longitudinal study. Assessment of their developmental progress in the areas of cognitive, motor, and adaptive skills occurred every 6 to 12 months. The progress of each subject over time and the progress of the group as a whole were analyzed by using a repeated-measures design and multiple t tests.', 'Developmental quotients did not improve over time for children with SLOS receiving cholesterol. In addition, baseline cholesterol levels, rather than age when supplementation began or increase in cholesterol levels, best predicted developmental outcome.'] Does cholesterol supplementation improve developmental progress in Smith-Lemli-Opitz syndrome?