Snapshot A 1-day-old infant girl is born to a G1P1 mother who had no serious complications during pregnancy but notes that she developed facial hair, severe acne, and deepening of her voice in her second and third trimesters. On physical examination, the infant appears to have ambiguous genitalia. A karyotype reveals that the infant is 46,XX. Genetic testing reveals a mutation in the CYP19A1 gene. Introduction Overview aromatase deficiency is a disorder of sexual development characterized by decreased levels of estrogen and increased levels of testosterone Epidemiology incidence < 1:1,000,000 fewer than 20 cases have been reported to date Pathophysiology mutation in the CYP19A1 gene, which codes for the enzyme aromatase aromatase converts androgens to estrogens ↓ aromatase activity leads to ↓ estrogen production and ↑ levels of androgens Genetics inheritance pattern autosomal recessive mutations CYP19A1 gene Presentation Symptoms both sexes hyperglycemia due to insulin resistance females lack of menstruation lack of breast growth Physical exam females infants ambiguous genitalia in female infants adolescence acne hirsutism during pregnancy maternal virilization excess fetal androgens may pass into the maternal bloodstream through the placenta males adolescence abnormal sperm production cryptorchidism abnormal bone growth Studies Gene sequencing will reveal a mutation in the CYP19A1 gene that codes for aromatase Differential 5α reductase deficiency key distinguishing factor 5α reductase deficiency is present only in genetic males (46,XY) testosterone and estrogen levels are normal Treatment Medical estrogen replacement leads to menses, breast develompent, and proper bone growth in females allows for proper bone growth in males Surgical surgical modification of ambiguous genitalia in females