Aromatase Deficiency

Aromatase Deficiency is an intersex condition in which one has reduced levels of estrogen and increased levels of testosterone. Those with this condition often have ambiguous genitals, are on the agenital spectrum, or have a enlarged clitorous. It is unknown how common this condition is, however approximately 20 cases have been described in the medical literature.

Those with XX chromosomes (individuals who would typically be AFAB) that have this condition often develop ovarian cysts in early childhood, which causes a lack of production of eggs in the ovaries. Because of this, they may have difiiculty getting pregnant, or have a sporadic menstrual cycle. This also tends to cause a lack of breast growth upon puberty, and excessive body hair.AMAB individuals with this condition often have infrequent sperm production and a decreased sex drive (unless they are on the ace-spectrum already.)

Both AMAB and AFAB individuals with this condition 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.

Causes
The cause of this 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 mother'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.

Resources

 * https://en.wikipedia.org/wiki/Aromatase_deficiency
 * https://medlineplus.gov/genetics/condition/aromatase-deficiency/#synonyms