XO/XY MOSAICISM: SHORT STATURE AND RESPONSE TO GROWTH HORMONE (GH) TREATMENT

Abstract

Children with 45,X/46,XY mosaicism are frequently reported to have mixed gonadal dysgenesis (MGD), a variant form of Turner syndrome (TS). However, surveys of prenatal chromosomal analyses find that 90-95% of newborns with XO/XY mosaicism have normal male genitalia. We report an 11 yr old boy with short stature, normal genitalia and XO/XY mosaicism. Since growth velocity and adult height are both improved in girls with TS treated with GH, we compared baseline characteristics and response to GH in TS, Turner mosaicism (XO/XX) (TM) and MGD in the National Cooperative Growth Study (NCGS) database, the NCGS contained data on 949 TS girls, 142 TM, 20 MGD females and 10 MGD males. At the time that GH therapy was begun, no significant differences were found for age, bone age, parental heights, or GH response to provocative stimuli. Boys with MGD were taller than the three groups of girls at initiation of GH therapy. In response to GH, growth velocity increased from 3.8±2.1 cm/yr (mean±SD) to 7.4±2.0 in TS, 4.0±2.1 to 7.5±2.2 in TM, and 3.9±2.0 to 7.5±1.5 in MGD after 1 yr of treatment. After 2 yrs of treatment, Bayley-Pinneau predicted adult heights increased by 0.6, 0.5 and 0.5 SD respectively. For the NCGS population, we conclude: Boys with MGD are taller at the time of treatment than girls with MGD, TS or TM; this may represent a sex based treatment bias, or a true biological difference. Otherwise, baseline characteristics are remarkably similar among these four groups of subjects. The short term increases in growth velocity and predicted adult height are similar in these four groups. Unrecognized 45,X/46,XY mosaicism in boys with short stature maybe more common than currently appreciated. As GH treatment may be beneficial, the clinical spectrum of this disorder needs to be better defined.