Tuberous sclerosis complex (TSC)

What changes during this transition

Tuberous sclerosis complex is an autosomal dominant tumor-predisposition syndrome caused by germline loss-of-function in TSC1 (chromosome 9q34, encoding hamartin) or TSC2 (chromosome 16p13, encoding tuberin). TSC2 mutations account for about three-quarters of cases and generally produce a more severe phenotype. Roughly two-thirds of cases are sporadic; one-third familial. The molecular consequence is the same regardless of which gene is hit: loss of the TSC1-TSC2 complex's inhibition of Rheb-GTP drives constitutive mTORC1 hyperactivation — unregulated cell growth, protein synthesis, proliferation, and autophagy suppression. Clinical manifestations span virtually every organ system and the surveillance regimen reflects that. CNS: cortical tubers, subependymal nodules, subependymal giant cell astrocytomas (SEGAs, ~10-15% — can cause hydrocephalus and obstructive symptoms requiring resection or pharmacotherapy); epilepsy in ~80-90% of patients (infantile spasms common in infancy — aggressive treatment essential, vigabatrin first-line); intellectual disability, autism spectrum disorder, and the broader TSC-associated neuropsychiatric disorder (TAND) constellation. Skin: hypomelanotic macules (ash-leaf spots — often the earliest finding), facial angiofibromas, shagreen patches, ungual fibromas, confetti lesions, café-au-lait spots. Kidney: angiomyolipomas in ~80% of adults (bilateral, multiple; lesions above 4cm carry hemorrhage risk — Wunderlich syndrome is a life-threatening retroperitoneal bleed); renal cysts; renal cell carcinoma at ~2-3% (higher than background population). Lung: lymphangioleiomyomatosis (LAM) in ~30-40% of adult women — progressive cystic lung disease with dyspnea, recurrent pneumothorax, chyle accumulation; reproductive-age females predominant and the natural history is estrogen-driven, with respiratory failure as the mortality endpoint in advanced disease. Heart: cardiac rhabdomyomas in ~50% of pediatric patients (often regress spontaneously but can cause arrhythmias and outflow obstruction in neonates). Eye: retinal hamartomas. Other: enamel pits, gingival fibromas, bone cysts, GI polyps, rare pancreatic neuroendocrine tumors. The 2012 / 2021 updated International TSC Consensus diagnostic criteria define definite TSC as either two major features, one major plus two minor, or a pathogenic TSC1/TSC2 variant on genetic testing. Surveillance per the 2013 / 2021 Krueger-Northrup Consensus recommendations: brain MRI every 1-3 years through age 25 then per clinical course, EEG with attention to infantile-spasms detection in infancy, annual renal MRI from age 12 for AML surveillance, baseline and serial dermatologic and ophthalmologic evaluation, dental review for enamel pits and gingival fibromas, cardiac evaluation in infancy, pulmonary function testing and HRCT chest in adult women for LAM screening, and annual neuropsychological/TAND assessment. Standard-of-care disease-modifying therapy is the mTOR-inhibitor class and is load-bearing: everolimus (Afinitor) is FDA-approved for SEGA (2010, EXIST-1), renal AML (2012, EXIST-2), and TSC-associated focal-onset seizures (2018, EXIST-3); sirolimus (Rapamune) is used via expanded access and as first-line therapy for moderate-to-severe LAM per the MILES trial, and as a topical formulation for facial angiofibromas. Cannabidiol (Epidiolex) received FDA approval in 2018 for TSC-associated seizures. Surgical management includes epilepsy surgery for refractory seizures, SEGA resection for hydrocephalus or obstruction, selective renal artery embolization or partial nephrectomy for symptomatic or large AMLs, and lung transplantation for end-stage LAM. The TSC Alliance (tscalliance.org) and the International TSC Alliance (ITSCA) provide patient advocacy, clinical-network coordination, and ongoing research support. The editorial substrate framing in the peptide context is sharp and pathway-level: TSC is the archetypal mTOR-pathway disease, and the GH-secretagogue family heavily marketed in longevity and body-composition spaces (CJC-1295, tesamorelin, ipamorelin) elevates IGF-1 — which signals through PI3K/Akt/mTOR, the exact pathway TSC1/TSC2 loss-of-function constitutively hyperactivates and the pathway everolimus and sirolimus suppress as standard of care. Adding upstream IGF-1 amplification to a patient on mTOR-inhibitor therapy is mechanistically opposed, joins the same pattern seen in HHT (where pro-angiogenic peptides oppose bevacizumab) and McCune-Albright / Carney complex (where GHRH-axis stimulation opposes the underlying PKA-driven adenoma biology), and applies across a multi-organ tumor-surveillance population where the GH/IGF-1 axis elevation is biologically the wrong direction. Family cascade screening obligations, infantile-onset diagnosis pathways via infantile spasms or prenatally detected cardiac rhabdomyomas, lifelong surveillance burden, and TAND-related life impacts make the editorial sensitivity of this substrate adjacent to NF1, VHL, and MEN1 — peptides are not the conversation; the multidisciplinary TSC team and the mTOR-inhibitor prescriber are. Sixty-fifth deliberate non-elevation.