Aromatase Deficiency

Aromatase Deficiency is an intersex variation in which one has reduced levels of estrogen and increased levels of testosterone. It is unknown how common this variation is, however approximately 20 cases have been described in the medical literature.

Those with XX chromosomes (CTF) that have this variation have ambiguous genitalia or an enlarged clitoris. They often develop ovarian cysts in early childhood, causing a lack of production of eggs in the ovaries, which often causes them to have AFAB Hypogonadism. Because of this, they may have difficulty getting pregnant, or have a sporadic menstrual cycle. This also tends to cause a lack of breast growth upon puberty, and excessive body hair.

Those with XY chromosomes (CTM) who have this variation often have infrequent sperm production and a decreased sex drive (unless they are already on the ace-spectrum and/or already not sex-favorable.) They may also have AMAB hypogonadism, microorchidism, and/or cryptorchidism.

Both AMAB/CTM and AFAB/CTF individuals with this variation seem to be abnormally tall, which causes thinner bones and a higher chance of injury due to the thin nature of the bones. They also tend to have high blood sugar, which causes them to gain weight and have a larger liver. This may classify them as physically disabled in some cases.

Causes
The cause of this variation appears to be when there is a mutation in ones CYP19A1 gene (the gene directly connected to an enzyme called aromatase, which controls estrogen and testosterone production.) Usually during fetal development, aromatase converts androgens/estrogens in the placenta, which is the link between the conceiving parent's blood supply and the fetus. This conversion in the placenta prevents androgens from directing sexual development in fetuses, which is what causes a long-term effect on the fetus's growth within it's parent.