Do young boys with fragile X syndrome have macroorchidism?

Macroorchidism is one of the most well-described clinical characteristics of men with fragile X syndrome, but little information has been available regarding macroorchidism in prepubertal boys with fragile X. The purpose of this study was to learn whether macroorchidism is a characteristic of fragile X syndrome in prepubertal boys.

Clinical assessments were performed on 73 boys, 2.2 to 10.2 years, in whom fragile X either had been diagnosed or who had been referred for fragile X evaluations because of developmental delays. As part of these assessments, we measured testicular volumes using Prader orchiometer beads to find out if macroorchidism occurs before the onset of puberty.

From 2.2 through 7 years, boys with fragile X have significantly larger mean testicular volumes than boys without fragile X, but macroorchidism (> or = 4.0 mL or > or = 2 times normal) only occurred in 1 of 27 boys with fragile X. From 8 to 10 years, all our patients with fragile X had clinically enlarged testicles (> or = 3.75 mL), and 7 of 9 boys with fragile X had macroorchidism (> or = 4.0 mL). The testicular volumes of control subjects were all < or = 3.0 mL.

These findings suggest that macroorchidism occurs in some prepubertal boys with fragile X, but in this series it did not occur until age 6 and usually did not occur until after age 8.