Reduced abdominal adiposity and improved glucose tolerance in growth hormone-treated girls with Turner syndrome.

BACKGROUND: Individuals with Turner syndrome (TS) are at increased risk for impaired glucose tolerance and diabetes mellitus. It is unknown whether pharmacological GH treatment commonly used to treat short stature in TS alters this risk. OBJECTIVE: Our objective was to compare adiposity and glucose tolerance in GH-treated vs. untreated girls with TS. METHODS: In a cross sectional study, GH-treated girls with TS (n = 76; age 13.6 +/- 3.7 yr) were compared to girls with TS that never received GH (n = 26; age 13.8 +/- 3.5 yr). Protocol studies took place in the NIH Clinical Research Center from 2001-2006 and included oral glucose tolerance tests, body composition analysis by dual-energy x-ray absorptiometry, and abdominal fat quantification by magnetic resonance imaging. GH was not given during testing. RESULTS: Total body fat (35 +/- 8 vs. 28 +/- 8%, P < 0.0001), sc abdominal fat (183 vs. 100 ml, P = 0.001), and intraabdominal fat (50 vs. 33 ml, P < 0.0001) were significantly greater in untreated girls. Fasting glucose and insulin were similar, but the response to oral glucose was significantly impaired in the untreated group (28 vs. 7% with impaired glucose tolerance, P = 0.006). A specific excess of visceral fat and insulin resistance was apparent only in postpubertal girls that had never received GH. GH-treated girls demonstrated lower adiposity compared with untreated girls for an average of 2 yr after discontinuation of GH. CONCLUSIONS: Abdominal adiposity is significantly lower and glucose tolerance significantly better in GH-treated vs. untreated girls with TS, suggesting that beneficial effects upon body composition and regional fat deposition outweigh transient insulin antagonism associated with GH administration.

The physical phenotype of girls and women with Turner syndrome is not X-imprinted.

Certain behavioral and metabolic aspects of Turner syndrome (TS) are attributed to X-chromosome genomic imprinting. To investigate the possible contribution of imprinting to the physical features of the TS phenotype in live-born individuals, we genotyped the single normal X-chromosome in subjects with TS who all underwent a comprehensive evaluation as part of the NIH genotype-phenotype protocol. All had physical examinations, auxological measurements and imaging of the renal and cardiovascular systems. Absolute height and height as a percent of predicted height was the same in X(M) (n = 56) and X(P) (n = 23) subjects that had reached final height and were not growth hormone treated. Interestingly, adult height was significantly correlated with maternal but not paternal heights in both X(M) and X(P) groups. Neck webbing was found in 35% of the X(M) (n = 133) and 22% of the X(P) (n = 50) groups (P = 0.11). Renal anomalies were present in 24% of X(M) and 25% of X(P) groups (P = 0.9). Bicuspid aortic valve was found in 26% of X(M) and 24% of X(P) groups (P = 0.83), and any cardiovascular anomaly (abnormal aortic valve, aortic coarctation, elongated transverse aortic arch, anomalous pulmonary venous connection, left superior vena cava) affected 55% of X(M) and 52% of X(P) groups. Thus, we found no evidence for X-linked genomic imprinting effects on stature or lymphatic, renal or cardiovascular development in TS. Our sample size was sufficient to exclude such effects within 95% confidence limits. We did demonstrate a selective maternal effect on final stature that was independent of X-chromosome origin, suggesting potential autosomal imprinting effects on growth revealed by X monosomy.