So all the excels a female individual will ever have are formed before birth. And what that means is, as the female individual actually ages, so do her ex cells. And so as that individual ages, her X cells ages. And as the excel age, the likelihood that nondisjunction will take place in meiosis and form an employed excels increases. And so if the likelihood of nondisjunction increases, that means the likelihood of down syndrome is also higher. So although the currents of down syndrome in the general population is actually very low, it's about zero point 15%, it increases with the increase in the maternal age in the age of that mother for the reason that we just discussed.