Turner Syndrome - Science topic

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Turner Syndrome typically has just 1 chromosome X (X0), so this means all the genes on the missing one are no present at all, and the female presents symptoms, when there is the inactivation of 1 X (XCI) the chromosome is "balled" called "Barr body", and some of the genes inside the inactivated one is working (about 15% ).

Will. thanks for your thought-provoking and helpful comment and the references.

It is interesting, the presumption that people who have a disability of some kind are automatically vulnerable, particularly as in ethics guidelines it often isn’t explained what it is about having a disability might make someone vulnerable. Does it depend on the type of disability? How does that interact with the individual’s own situation: ie their experience of having that disability or the way they manage it could vary? It is interesting to think about.

Liz, yes, I am planning for my screening questionnaire to include questions about adaptions. Although I’m a bit concerned that giving participants too many options might present problems for people with executive function difficulties, who find it hard to make decisions, so it would be good if I could take on some of that myself where possible. Some of this will get untangled by piloting it.

This is a PhD project but I’m a mature student; I’ve volunteered in the fertility field for a while and have conducted related research before. I also used to be an accessibility tester/auditor and, while I haven’t worked directly with people with disabilities very often, I understand how adaptions can be put in place. It’s more about which ones to use and in which circumstances.

 I’ve also spoken to the TS charity and a couple of TS doctors and got the impression that I was being overly cautious in going to lengths to make my research methods accessible. If the participant group and the charity that represents them doesn’t consider themselves to have a disability then who am I, etc etc. However on the other side, there is the research evidence. My participants will be women who are looking at egg donation or adoption as a method of family-building (and most will have partners) so (from my perspective) the issue is not one of capacity, it’s about creating an environment where they feel able to say what they want to say in the way that works best for them and causes the least possible stress. Hence I’m tweaking a standard method rather than going for a participative approach.

I hadn’t heard of Kirsty Liddiard so thanks for that tip.

And Paul, thank you for your thoughtful comment.

There is a very recent case report with free text available: 

Ann Card Anaesth. 2016 Jan-Mar;19(1):166-8. doi: 10.4103/0971-9784.173041.

Perceval S aortic valve implantation in an achondroplastic Dwarf.

Baikoussis NG1, Argiriou M, Argiriou O, Dedeilias P.

Author information

 

Abstract

Despite cardiovascular disease in patients with dwarfism is not rare; there is a lack of reports referring to cardiac interventions in such patients. Dwarfism may be due to achondroplasia or hormonal growth disorders. We present a 58-year-old woman with episodes of dyspnea for several months. She underwent on transthoracic echocardiography, and she diagnosed with severe aortic valve stenosis. She referred to our department for surgical treatment of this finding. In accordance of her anthropometric characteristics and her very small aortic annulus, we had the dilemma of prosthesis selection. We decided to implant a stentless valve to optimize her effective orifice area. Our aim is to present the successful Perceval S valve implantation and the descriptions of the problems coming across in operating on these special patients. To our knowledge, this is the first case patient in which a Perceval S valve is implanted according to the international bibliography.

I gather you mean an NIPT result showing Turner's Syndrome (XO genotype). As NIPT is a screening test, it would be important to consider confirming the diagnosis with a diagnostic test ie chorionic villus sampling or amniocentesis. The obtained sample should be sent for chromosome culture to confirm the diagnosis.

Once confirmed, evaluation of the fetus for associated abnormalities can be performed by ultrasound. Hear defects, in particular, may occur in 15-30% of fetuses. Subsequent management should be individualised. The prognosis for a fetus without structural abnormalities is good. Intellectual development is normal and, with the exception of premature ovarian failure, is not different from a non-affected individual.

the fate of embryonic germ cells is conditioned by their sex chromosomal constitution. Female germ cells (that bear a 46,XX constitution) enter meiosis during embryonic life and arrest at the diplotene stage until the moment of oocyte development after puberty. Male germ cells (with a 46XY constitution) supress meiotic development until puberty.

Turner patients generally have a 45X0 constitution (that is lack one X chromosome). At the moment these fetal cells attempt to enter meiosis this process cannot be completed (because of the lack of one X chromosome) and undergo degeneration. That is why ovaries from X0 ovaries do not contain oocytes in the neonate. Some Turner patients have a mosaic constitution (46XX and 46X0 in different proportions). The 46XX primitive female germ cells are succesful in going through meiosis and reach the diplotene stage where they arrest until puberty. The reason why some Turner patients have oocytes in their ovaries is because they have a mosaic chromosomal constitution including a 46XX line that succeds in going through meiosis. 

does this mean the few genes on barr body are deciding factor for female reproductive physiology and other differentiation or they work synergistic with their counterparts on active X chromosome?