Is primary macronodular adrenal hyperplasia inherited ?
People with PMAH caused by ARMC5 gene mutations inherit one copy of the mutated gene in each cell. The inheritance is considered autosomal dominant because one copy of the mutated gene is sufficient to make an individual susceptible to PMAH. However, the condition develops only when affected individuals acquire another mutation in the other copy of the ARMC5 gene in certain cells of the adrenal glands. This second mutation is described as somatic. Instead of being passed from parent to child, somatic mutations are acquired during a person's lifetime and are present only in certain cells. Because somatic mutations are also required for PMAH to occur, some people who have inherited the altered ARMC5 gene never develop the condition, a situation known as reduced penetrance.  When PMAH is caused by GNAS gene mutations, the condition is not inherited. The GNAS gene mutations that cause PMAH are somatic mutations. In PMAH, the gene mutation is believed to occur early in embryonic development. Cells with the mutated GNAS gene can be found in both adrenal glands.