Abstract
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.
Highlights
Turner syndrome (TS) is defined as the combination of short stature, gonadal dysgenesis, typical visible somatic dysmorphic stigmata, and urinary, cardiovascular, metabolic and skeletal abnormalities associated with a missing or structurally abnormal second sexual chromosome [1]
Among the group of subjects who retained the paternal X chromosome (Xp) no correlation was demonstrated at any age group
In the largest study carried out to date (n = 128 (Xm) vs n = 52 (Xp), Deverny et al demonstrated the parental origin of the X-chromosome did not alter the effect of Recombinant human growth hormone (rhGH) treatment [15]. Due to all these results, we propose that the parental origin of the retained X chromosome should not be taken into account when therapy with rhGH in TS patients is individualized
Summary
Turner syndrome (TS) is defined as the combination of short stature, gonadal dysgenesis, typical visible somatic dysmorphic stigmata, and urinary, cardiovascular, metabolic and skeletal abnormalities associated with a missing or structurally abnormal second sexual chromosome [1]. The absence of the second sexual chromosome has led to the speculation that there may be genes present on the X chromosome which are expressed differently depending upon whether they are maternally or paternally derived [3]. Both the haploinsufficiency of genes on the two sexual chromosomes and the parental origin (monoallelic expression of the imprinted genes) may play a part in the broad and variable clinical features spectrum seen in TS. 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
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