CYP19A1 and hyperinsulinemic hypoglycemia, familial, 4: Whole exome sequencing was done, which reported that the baby was carrying a novel homozygous mutation of the <i>CYP19A1</i> gene c.575G>C p. (Arg192Pro), confirming the diagnosis of aromatase deficiency.<h4>Conclusions</h4>Aromatase deficiency is a rare condition.