However, it is estimated that 3 to 8 percent of girls with a single X chromosome and 12 to 21 percent of females with sex chromosome mosaicism may have normal pubertal development and spontaneous menstrual periods.
Subsequently, however, researchers concluded that the rare recurrence of OI to a couple with a child with autosomal dominant OI is more likely due to gonadal mosaicism.
An estimated 2 percent to 4 percent of families into which an infant with OI type II is born are at risk of having another affected child because of gonadal mosaicism.
Another feature of fragile X syndrome is that mosaicism is present in 15 to 20 percent of those affected by the condition.
Faivre, L., et al. "Recurrence of achondrogenesis type II within the same family: evidence for germline mosaicism."