About this Research Topic
Turner syndrome (TS) is a relatively common chromosomal disorder affecting approximately 1 in 2000 live female births. Short stature is the most common clinical presentation of the syndrome; it is observed in 80 % to 100 % of the girls with TS. Growth is stunted to a variable degree at different phases of childhood and adolescence in TS. Although there is consensus on treating growth failure as early as possible, there is ongoing research to ameliorate final height in TS girls. The co-existence of primary ovarian failure in girls with TS further complicates the management of short stature. It remains to be determined what is the best age to begin treatment for pubertal induction and/or maintenance of puberty; the best compound, dose, or protocol to induce puberty.
TS patients have increased mortality and morbidity due to cardiovascular (CV) complications and multiple risk factors for ischaemic heart disease, including hypertension, insulin resistance and dyslipidaemia. The CV phenotype can be better assessed through identification of surrogate risk markers and the relationship of these markers with TS - associated traits. There are very few comprehensive studies on the dynamics of arterial tree and the associations of these dynamics with influential factors in young TS patients.
The B-type natriuretic peptide (BNP) has recently been shown to be associated with arterial stiffness and aortic diameters in TS patients. BNP is involved in cardiac remodeling and is related to subclinical CV damage. Short stature homeobox gene plays a role in the genotype and phenotype of TS through haploinsufficiency and induces the upregulation of the NP precursor B gene, which codes for the synthesis of BNP. The reason for the increased BNP levels in TS is not clear. Rather than being a causal factor in deterioration of arterial stiffness, we speculate that the positive association of BNP with arterial stiffness may reflect a compensatory rise in BNP in opposition to the fibrotic effects of transforming growth factor-beta, as was shown in vitro. The hormones of the somatotropic axis, GH and IGF1 are involved in the regulation of the CV system. Deregulated signalling within the GH-IGF1 axis may extend beyond the realm of physical stature in TS, resulting in effects on the CV system and other organ systems. Although GH deficiency is associated with CV risk , and excess of GH is also associated with increased CV risk. Because TS patients receive supraphysiological doses of GH, there may be increased risks for CV complications, although retrospective studies failed to document such an association. There are still other unknown issues in the area of TS and CV issues such as the definitions of "abnormal" aortic diameters, high blood pressure. There is scarce data regarding how we can prevent catastrophic CV events in girls and women with TS. There is a call for prospective studies regarding the pathogenesis, diagnosis and prevention of CV disease in TS.
Management of infertility in patients with TS is a hot topic of research, although spontaneous pregnancy can be achieved in up to 2 % to 5 % of the patients. The co-existence of CV disease in the majority of the TS patients confers a high risk of maternal complications. The presence of functional ovaries at evaluation determines the management strategy; TS patients with functional ovaries should be advised not to postpone pregnancy unless a reasonable indication exists. The availability of oocyte preservation methods should be decisive in the timing of pregnancy. Oocyte or embryo transfer can be considered in TS patients without functional ovaries. However, issues regarding the competency of the uterus for maintenance of a viable fetus should be addressed.
TS patients usually have psychological problems related to self-confidence and self-respect due to the high burden of health-related issues they have to cope with at different stages of life. There remains controversy on how to support them to accept their differences and empower them to take an active role in their care.
Keywords: Turner syndrome, natriuretic peptides, growth hormone, cardiovascular risk, short stature, insulin like growth factor-1, puberty, fertility, psychosocial
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