The present invention provides methods and compositions for treating a disorder associated with a deficiency in a gene product of a CLN gene in a subject ), comprising administering to the subject an effective amount of a sphingolipid, thereby treating the disorder in the subject. The two single-axis gyroscopes may be interconnected, e. The light-emitting device and heat sink may be included in a light fixture. A number of individual element arrays are arranged along the lines of the first type and lines of the second type.