Genetics of Macromastia

Aromatase excess syndrome is a condition characterized by elevated levels of the female sex hormone estrogen in females which leads to increased breast growth (macromastia) and irregular menstrual periods. Rearrangements of genetic material involving the CYP19A1 gene cause aromatase excess syndrome. Th gene provides instructions for making an enzyme called aromatase. This enzyme converts a class of hormones called androgens, which are involved in male sexual development, to different forms of estrogen. In females, estrogen guides female sexual development before birth and during puberty. In both males and females, estrogen plays a role in regulating bone growth. The condition can result from several types of genetic rearrangements involving the CYP19A1 gene. These rearrangements alter the activity of the gene and lead to an increase in aromatase production . This condition is inherited in an autosomal dominant pattern, which means a genetic rearrangement involving one copy of the CYP19A1 gene in each cell is sufficient to cause the disorder. In some cases, an affected person inherits the mutation from one affected parent. Other cases result from new genetic changes and occur in people with no history of the disorder in their family.