Liliana Silvano

Serum levels of adiponectin and leptin in children born small for gestational age: relation to insulin sensitivity parameters.

ABSTRACT Children born small for gestational age (SGA) are prone to developing obesity, insulin resistance and type 2 diabetes. Adiponectin and leptin are adipocytokines associated with insulin sensitivity parameters. We aimed to relate serum adiponectin and leptin levels with insulin sensitivity parameters in prepuberal SGA children with and without catch-up growth (SGA+CUG; SGA-CUG, respectively) and to analyze the usefulness of these adipocytokines as early markers of insulin resistance. We analysed adiponectin, proinsulin, leptin, growth factors, insulin, HOMA IR and HOMA βcell in 23 SGA+CUG, 26 SGA-CUG children compared with 48 prepuberal appropiate for gestational age (AGA). SGA children had adiponectin levels comparable to AGA children. Leptin levels were different between sexes, showed to be higher in SGA+CUG group (p=0.040) and these were significantly correlated with insulin sensitivity parameters. These results suggest leptin resistance as an adaptive mechanism to increase energy balance, but an altered functional response of adipocytes cannot be discarded.

Effect of the parental origin of the X-chromosome on the clinical features, associated complications, the two-year-response to growth hormone (rhGH) and the biochemical profile in patients with turner syndrome

BackgroundIt is possible that genes on the X chromosome are expressed differently depending of its parental origin. The objective of this study was to determine the influence of the parental origin of the X-chromosome on phenotypic variability, response to rhGH and on the biochemical profile of TS patients.MethodsThis was a cross-sectional multicenter correlational study carried out over three years in six Latin-American university hospitals. Unrelated 45,X TS patients (n =  93; 18.3 ± 8.5 years )) were evaluated. A subgroup (n =  34) of the patients were prospectively treated with rhGH over two years. DNA profiles of patients and their mothers were compared to determine the parental origin of the retained X-chromosome through 10 polymorphic X-chromosome-STRs. The association with clinical features, biochemical profiles and anthropometric data at the beginning and after two years of rhGH treatment was determined.ResultsSeventy two percent of patients retained the maternal X chromosome (Xm). A trend towards significance between maternal height and patients final height (p ≤ 0.07) in 45,Xm subjects was observed. There was no correlation between paternal height and patient height. No differences were detected between both groups in regard to dysmorphic features, classical malformations or increase in the height-SDS after rhGH. There were higher levels of triglycerides, total and LDL cholesterol in patients >20 years who retained the Xm.ConclusionsThe parental origin of the retained X chromosome may influence lipid metabolism in TS patients, but its effect on growth seems to be minimal. No parental-origin-effect on the phenotypic features, associated anomalies and on the growth response to rhGH was found in 45,X TS individuals.

Vitamin D receptor genotypes are associated with bone mass in patients with Turner syndrome.

Abstract Background: Turner syndrome (TS) patients present low bone mineral density (BMD) and increased fracture risk, probably due to a genetic defect aggravated by hormonal deficiency. Aim: To study the relationship between vitamin D receptor (VDR) gene polymorphisms and BMD and bone parameters in TS patients. Methods: DNA from 65 TS patients and 110 controls was amplified by PCR and digested with Fok I, Bsm I and Apa I restrictases. Lumbar and femoral BMD were determined by DEXA and serum intact parathyroid hormone, osteocalcin and β-CrossLaps by electrochemiluminescence. Results: Genotype distribution within the Apa I site was different in both groups: genotype Aa was more abundant in TS (63.8% vs. 41.3%; p<0.01), whereas AA predominated in controls (33.9% vs. 15.5%; p<0.01). Patients carrying genotype bb (Bsm I) or ff (Fok I) had lower BMD than those with other genotypes (p<0.01 and p<0.05, respectively). Conclusion: Bsm I and Fok I polymorphic sites of VDR could be genetic determinants of BMD in TS patients.

Association of vitamin D receptor gene Cdx2 polymorphism with bone markers in Turner syndrome patients.

Abstract Background: Turner syndrome (TS) patients usually have low bone mineral density (BMD) and increased risk of osteoporotic fractures. We have previously demonstrated an association of bb (BsmI polymorphic site) and ff (FokI polymorphic site) vitamin D receptor (VDR) genotypes with reduced BMD in TS patients. Aim: To analyze the relationship between VDR-Cdx2 polymorphism and BMD as well as bone metabolic variables in TS patients. Methods: Fifty-five TS patients and 59 control women were studied. VDR-Cdx2 genotypes were determined using TaqMan probes in a real time thermocycler. Lumbar and femoral BMD were determined by dual-energy X-ray absorptiometry (DEXA) and serum intact parathyroid hormone, osteocalcin and β-CrossLaps were determined by electrochemiluminescence. Results: Patients with genotype GG had higher levels of both osteocalcin and β-CrossLaps as compared to patients with genotype GA (p<0.01 and p<0.05, respectively). Conclusion: Patients carrying genotype GG have higher levels of bone formation and resorption markers. This indicates a more active bone turnover that could impact on their future bone mineral density.

Clinical and molecular studies related to bone metabolism in patients with congenital adrenal hyperplasia

Abstract Patients with congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency need glucocorticoid (GC) therapy, which alters bone mineral metabolism. We analyze clinical and biochemical parameters and different polymorphisms of candidate genes associated with bone mineral density (BMD) in CAH patients. The CAH patients treated with GC and healthy controls were studied. Anthropometric parameters, biochemical markers of bone turnover, and BMD were evaluated. Polymerase chain reaction technique was used to genotype different candidate genes. The 192-192 genotype frequency (IGF-I) was lower in poorly controlled patients than that from controls. In CAH patients, FF genotype (vitamin D receptor, VDR) correlated with lower lumbar spine BMD and there was a significant association between the 0-0 genotype (IGF-I) and high values of β-CrossLaps and a low total BMD. This study contributes to understanding of the association of genetic determinants of BMD with the variable response to GC treatment in CAH patients and demonstrates the usefulness of these genetic polymorphisms.