This Review describes important advances in the TSC field and highlights several remaining critical knowledge gaps: the factors that promote aggressive behaviour by a subset of TSC-associated RCCs; the molecular mechanisms underlying early-onset cystogenesis in TSC2-PKD1 contiguous gene deletion syndrome; the effect of early, long-term mTORC1 inhibition on the development of TSC renal disease; and the identification of the cell or cells of origin of angiomyolipomas.
PKD1 lays immediately adjacent to TSC2 and deletions involving both genes, the PKD1/TSC2 contiguous gene syndrome (CGS), are characterized by severe ADPKD, plus TSC. mTOR inhibitors have proven effective in reducing angiomyolipoma (AML) in TSC and total kidney volume in ADPKD but without a positive effect on renal function.
Although extremely rare, TSC and autosomal dominant polycystic kidney disease (ADPKD) can co-exist in the same patient as a result of concurrent deletion of both polycystic kidney disease (PKD) 1 and TSC2 genes present on the chromosome 16p13.3.
Patients with TSC often develop renal cysts and those with inherited co-deletions of the autosomal dominant polycystic kidney disease (ADPKD) 1 gene (PKD1) develop severe, early onset, polycystic kidneys.
Clinical awareness and appropriate molecular investigation of TSC2/PKD1 contiguous gene syndrome is necessary in all patients with a typical phenotype of TSC in infancy, adolescence, or adult age, because of severity of the renal alterations.
Our results confirm that patients with both TSC and PKD have a genetically contiguous gene syndrome with hemizygous deletion of the TSC2 and PKD1 genes.
The clinical and pathological presentation is consistent with the diagnosis of TSC2/PKD1 contiguous gene syndrome, caused by the simultaneous loss of TSC2 and PKD1, the two major genes for tuberous sclerosis complex and ADPKD.
A TSC2-PKD1 contiguous gene syndrome caused by chromosomal microdeletions disrupting both the TSC2 and PKD1 genes has been identified in patients with TSC and early-onset severe ADPKD.
Recently, a deletion mutation disrupting both TSC2 and PKD1 has been described in young children with tuberous sclerosis complex with severe renal cystic disease.
We have sequenced 1949 kb from the terminal Giemsa light band of human chromosome 16p, enabling us to fully annotate the region extending from the telomeric repeats to the previously published tuberous sclerosis disease 2 (TSC2) and polycystic kidney disease 1 (PKD1) genes.
The presence of a deletion involving both TSC2 and PKD1 genes should be considered in the clinical assessment of TSC children with an early-onset polycystic kidney disease, and more generally in all ADPKD patients who develop end-stage renal failure prior to the fourth or fifth decade of life.
Major genes for tuberous sclerosis and autosomal dominant polycystic kidney disease, TSC2 and PKD1, respectively, lie adjacent to each other at chromosome 16p13.3, suggesting a role for PKD1 in the etiology of renal cystic disease in tuberous sclerosis.
However, a number of patients with large deletions of the PKD1 and adjacent tuberous sclerosis 2 (TSC2) genes, who have tuberous sclerosis and severe childhood-onset polycystic kidney disease, have also been described.
Major genes which cause tuberous sclerosis (TSC) and autosomal dominant polycystic kidney disease (ADPKD), known as TSC2 and PKD1 respectively, lie immediately adjacent to each other on chromosome 16p.