Renal involvement in tuberous sclerosis complex with emphasis on cystic lesions

The extent of kidney involvement in paediatric tuberous sclerosis complex

BACKGROUND

Tuberous sclerosis (TSC)-associated kidney disease is a leading cause of mortality in adults with TSC. This study aimed to understand TSC features in children, particularly kidney involvement, to inform clinical care for this specific group.

METHODS

This retrospective cohort study included all paediatric (< 19 years) TSC cases at a large tertiary paediatric nephrology centre. Relevant data were collected from patients' records, statistical analyses were performed to identify associations between variables, survival probabilities were estimated with Kaplan‒Meier curves, and log-rank tests were conducted to assess survival differences among genetic mutations.

RESULTS

A total of 182 children with TSC were included. Among the 145 children with available kidney imaging data, 78.6% (114/145) exhibited kidney lesions. Angiomyolipomas (AMLs) were significantly more prevalent in the TSC2 mutation group (p = 0.018). Children with TSC2 mutations generally had poorer lesion-free survival than those with TSC1 mutations, but this difference was only significant for AMLs (p = 0.030). The change in size of largest AMLs increased with age and doubled in children above 9 years; a similar pattern was observed when stratified by genetic mutation. In contrast, kidney cysts exhibited two peaks: one in children under 5 years (2.31 mm/year) and the second in children between 15-19 years (2.82 mm/year). Chronic kidney disease was observed in 12.3% (10/81) of children, and high-risk AMLs above 3 cm were observed in 9% (13/145).

CONCLUSIONS

While TSC kidney disease emerges later in the disease course than neurological features, our findings emphasise the importance of kidney surveillance during childhood, including routine kidney imaging, kidney function, and blood pressure monitoring.

Clinical practice recommendations for kidney involvement in tuberous sclerosis complex: a consensus statement by the ERKNet Working Group for Autosomal Dominant Structural Kidney Disorders and the ERA Genes & Kidney Working Group

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by the presence of proliferative lesions throughout the body. Management of TSC is challenging because patients have a multifaceted systemic illness with prominent neurological and developmental impact as well as potentially severe kidney, heart and lung phenotypes; however, every organ system can be involved. Adequate care for patients with TSC requires a coordinated effort involving a multidisciplinary team of clinicians and support staff. This clinical practice recommendation was developed by nephrologists, urologists, paediatric radiologists, interventional radiologists, geneticists, pathologists, and patient and family group representatives, with a focus on TSC-associated kidney manifestations. Careful monitoring of kidney function and assessment of kidney structural lesions by imaging enable early interventions that can preserve kidney function through targeted approaches. Here, we summarize the current evidence and present recommendations for the multidisciplinary management of kidney involvement in TSC.

Cystic kidney disease in tuberous sclerosis complex: current knowledge and unresolved questions

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder with an estimated incidence of one in 5000 to 10,000 live births worldwide. Two million people of all races and genders are estimated to have TSC secondary to mutations in one of two tumor suppressor genes, TSC1 or TSC2. The respective TSC1 and 2 gene products - hamartin and tuberin - form cytoplasmic heterodimers that inhibit mTOR-mediated cell growth and division. When mTOR inhibition is lost, people with TSC develop characteristic and usually benign tumors in various organ systems. Kidney tumors and cysts are common, particularly in the setting of TSC2 gene mutations. In most TSC patients, the number of kidney cysts is limited, their morphology is simple, their size is small, and their clinical significance is negligible. In some, cyst morphology progresses from simple to complex with the risk of malignant transformation. In others, aggressive accumulation and growth of kidney cysts can cause hypertension, impaired kidney function, and progression to kidney failure. This educational review summarizes current knowledge and remaining open questions regarding cystic kidney disease in TSC, emphasizing detection, classification, surveillance, and treatment options.

TSC2/PKD1 contiguous deletion syndrome in a pregnant woman: A case report

TSC2/PKD1 contiguous gene deletion syndrome is a disease caused by the deletions of the TSC2 and PKD1 genes. This is a rare contiguous genomic disease with clinical manifestations of tuberous sclerosis and polycystic kidney disease. To our knowledge, this case report is the first known case of TSC2/PKD1 contiguous gene deletions in a pregnant woman. The patient had multiple renal cysts, angiomyolipoma, hypomelanotic macules, shagreen patch, subependymal giant cell astrocytoma, multiple cortical tubers, and subependymal nodules. The patient underwent genetic testing. To exclude genetic defects in the fetus, prenatal fetal genetic testing was performed after obtaining the patient's consent. We found an increasing trend in the size of renal cysts and renal angiomyolipomas in patients with polycystic kidney with tuberous sclerosis during pregnancy. Through enhanced clinical monitoring of patients and prenatal genetic testing of the fetus, timely and effective clinical intervention for the mother may be achieved, thus obtaining the best possible outcome for both mother and fetus.

TSC1 and TSC2: Tuberous Sclerosis Complex and Its Related Epilepsy Phenotype

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by a multisystemic involvement. In TSC, reduced function of TSC1 and TSC2 genes products (hamartin and tuberin, respectively) leads to an hyperactivation of the mechanistic target of rapamycin (mTOR) pathway and to a consequent cell growth dysregulation. In TSC patients, neurological and neuropsychiatric manifestations, especially epilepsy and neuropsychiatric comorbidities such as autism or intellectual disability, represent the most disabling features. In particular, epilepsy occurrs up to 80% of patients, is often drug resistant and is frequently associated with neurological impairment. Due to the burden of this morbidity, different treatment strategies have been proposed with the purpose to make patients epilepsy free, such as the use of different antiepileptic drugs like vigabatrin, carbamazepine, valproic acid, and levetiracetam. More recently, a mTOR inhibitor (i.e. everolimus) has showed promising results in terms of seizures reduction.

Beyond polycystic kidney disease

Tuberous sclerosis(TS) is an autosomal dominant disease caused by mutations in TSC1 and TSC2 genes. TSC2 gene is located in chromosome 16p13.3, adjacent to PKD1 gene, responsible for the autosomal dominant polycystic kidney disease. In a rare subgroup of patients, the presence of a deletion which simultaneously affects the TSC2 and PKD1 genes has been confirmed. TSC2/PKD1-Contiguous Gene Syndrome is characterised by the early appearance of autosomal dominant polycystic kidney disease in combination with several phenotypic manifestations of TS. We present a 13-year-old girl with bilateral renal cysts detected at the age of 9 months. At the age of 13, she was referred to the Dermatology Outpatients Clinic due to a facial cutaneous eruption. She presented with facial erythema, fibroadenomas with malar distribution and disseminated hypomelanotic macules, meeting the criteria for TS. TSC2/PKD1 Contiguous Gene Syndrome deletion was suspected, being later confirmed by genetic testing.