SF-1/NR5A1 mutations are frequently found in 46,XY DSD individuals (9%) and manifest with a broad phenotype. Testes histology is characteristic for fat accumulation and degeneration over time, similar to findings observed in patients with lipoid congenital adrenal hyperplasia (due to StAR mutations). Genotype-structure-function-phenotype correlation remains elusive.

MAMLD1 is thought to cause disordered sex development in 46,XY patients. But its role is controversial because some MAMLD1 variants are also detected in normal individuals, several MAMLD1 mutations have wild-type activity in functional tests, and the male Mamld1-knockout mouse has normal genitalia and reproduction. Our aim was to search for MAMLD1 variations in 108 46,XY patients with disordered sex development, and to test them functionally. We detected MAMDL1 variations and compared SNP frequencies in controls and patients. We tested MAMLD1 transcriptional activity on promoters involved in sex development and assessed the effect of MAMLD1 on androgen production. MAMLD1 expression in normal steroid-producing tissues and mutant MAMLD1 protein expression were also assessed. Nine MAMLD1 mutations (7 novel) were characterized. In vitro, most MAMLD1 variants acted similarly to wild type. Only the L210X mutation showed loss of function in all tests. We detected no effect of wild-type or MAMLD1 variants on CYP17A1 enzyme activity in our cell experiments, and Western blots revealed no significant differences for MAMLD1 protein expression. MAMLD1 was expressed in human adult testes and adrenals. In conclusion, our data support the notion that MAMLD1 sequence variations may not suffice to explain the phenotype in carriers and that MAMLD1 may also have a role in adult life.

Metastatic pheochromocytoma and paraganglioma (mPHEO/PGL) are frequently associated with succinate dehydrogenase B (SDHB) mutations. Cyclophosphamide-dacarbazine-vincristine (CVD) regimen is recommended as standard chemotherapy for advanced mPHEO/PGL. There is limited evidence to support the role of metronomic schemes (MS) of chemotherapy in mPHEO/PGL treatment. We report 2 patients with SDHB-related mPGL who received a regimen consisting of MS temozolomide (TMZ) and high-dose lanreotide after progression on both CVD chemotherapy and high-dose lanreotide. Molecular profiling of the tumor tissue from both patients revealed hypermethylation of the O6-methylguanine-DNA-methyltransferase (MGMT) promoter. In one patient, progression-free survival was 13 months and the second patient remained under treatment after 27 months of stabilization of metabolic response of his disease. Treatment was well tolerated, and adverse effects were virtually absent. A modification in the scheme of TMZ from standard schemes to MS is safe and feasible and can be considered in patients with progressive mPHEO/PGL refractory to dacarbazine in standard doses.

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