We hope to study the differences between cultured skin fibroblasts from patients with different types of cystinosis. We plan to make somatic cell hybrids between cultured cells from patients with the three different types of cystinosis. It is very possible that we will find genetic complementation in that the somatic cell hybrids will then contain normal amounts of free cystine. If this is true, we will be able to establish a number of complementation groups of cystinotic cells and thereby have a more accurate manor of classifying cystinotic patients.