Severe lupus nephritis in a young adult with PTEN hamartoma tumour syndrome.

On chromosome 10q23 is found the PTEN gene, which encodes a phosphate and tension homologue. The protein dephosphorylates phosphatidylinositol-(3,4,5)-trisphosphate at the plasma membrane to produce inorganic phosphatidylinositol-(4,5)-bisphosphate. This enzymatic activity inhibits the phosphatidylinositol-3-kinase, protein kinase B and mammalian target of the rapamycin signalling cascade. Consequently, essential cellular functions, including metabolic regulation, cellular growth, proliferation and viability, are affected. A mutation in this gene gives rise to hamartoma tumour syndrome, which exhibits a range of phenotypes, including Bannayan-Riley-Ruvalcaba syndrome, Cowden syndrome and proteus-like disease. A man in his late 20s with a PTEN tumour-like arteriovenous malformation in the right thigh was recently diagnosed with lupus nephritis. The patient's nephritic symptoms, pleural effusion, dyslipidaemia and splenomegaly demonstrate systemic lupus erythematosus (SLE) multisystem involvement. The case report identifies an association between a PTEN mutation and a new diagnosis of SLE that might have been triggered by PTEN-associated immune dysregulation.