Acrofacial dysostosis in a patient with the TSC2-PKD1 contiguous gene syndrome

Tuberous sclerosis (TSC) is an autosomal dominant trait with variable expression most frequently characterised by neurological impairment (seizures and learning difficulties), by dermatological manifestations (facial angiofibromas, periungual fibromas, shagreen patches, and hypopigmented macules), and by renal manifestations including angiomyolipomas and cystic disease. 3 The second gene for TSC, TSC2, maps to chromosome 16p13.3 tail to tail with the major gene for autosomal dominant polycystic kidney disease (ADPKD), the PKD1 gene. The substrate of the transporter is not known but the highest mRNA expression has been seen in lung tissue. 17 In general, deletions spanning TSC2 and PKD1 have been implicated in a severe and infantile form of polycystic kidney disease in TSC. 35 Progression of renal cystic disease is apparently accelerated when, in addition to inactivation of the PKD1 gene, TSC2 function is lost.