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Hereditary pheochromocytoma (PCC) is often caused by germline mutations in one of nine susceptibility genes described to date, but there are familial cases without mutations in these known genes. We sequenced the exomes of three unrelated individuals with hereditary PCC (cases) and identified mutations in MAX, the MYC associated factor X gene. Absence of MAX protein in the tumors and loss of heterozygosity caused by uniparental disomy supported the involvement of MAX alterations in the disease. A follow-up study of a selected series of 59 cases with PCC identified five additional MAX mutations and suggested an association with malignant outcome and preferential paternal transmission of MAX mutations. The involvement of the MYC-MAX-MXD1 network in the development and progression of neural crest cell tumors is further supported by the lack of functional MAX in rat PCC (PC12) cells and by the amplification of MYCN in neuroblastoma and suggests that loss of MAX function is correlated with metastatic potential.

Congenital hypopituitarism due to pituitary stalk and anterior pituitary hypoplasia accompanied by an ectopic posterior pituitary lobe is a rare disorder causing multiple hormone deficiencies. Clinical signs can be present at birth (hypoglycemia, prolonged jaundice and micropenis) and there can be severe growth restriction. Therefore, diagnosis is usually performed in childhood. We present the uncommon case of a 67-year-old man with hypopituitarism due to hypoplasia of the anterior pituitary and pituitary stalk together with an ectopic posterior pituitary who presented symptoms of hyponatremia due to adrenocorticotropic hormone deficiency.