Figure 935

Tuberous sclerosis complex (TSC): genetics. Representative examples of various contiguous deletions of the PKD1 and TSC2 genes in five patients with TSC and prominent renal cystic involvement (the size of the deletion in each patient is indicated).

TSC is genetically heterogeneous. Two genes have been identified. The TSC1 gene is on chromosome 9, and TSC2 lies on chromosome 16 immediately adjacent and distal to the PKD1 gene. Half of affected families show linkage to TSC1 and half to TSC2. Nonetheless, 60% of TSC cases are apparently sporadic, likely representing new mutations (most are found in the TSC2 gene) [34]. The proteins encoded by the TSC1 and TSC2 genes are called hamartin and tuberin, respectively. They likely act as tumor suppressors; their precise cellular role remains largely unknown. The diseases caused by type 1 and type 2 TSC are indistinguishable except for renal cysts, which, so far, have been observed only in TSC2 patients [33], and for intellectual disability, which is more common in TSC2 patients [34]. (Adapted from Sampson, et al. [33].)

0 0

Post a comment