All About Turner Syndrome

Introduction

Turner syndrome is a chromosomal condition, caused by deletion of all the second sex chromosomes or part of them. It is approximated that one in two thousand five hundred live female births is a turner syndrome patient. In pediatric practice, Turner syndrome is one of the most frequent conditions encountered in genetics. There could be effect to body systems in degrees that vary and present the pediatrician with diagnostic and management challenges. The challenges are predicted partly by the child's karyotype, and some by life and other social experiences of the child developing. Therefore, management of females with Turner syndrome is appropriate and requires discipline that is multidisciplinary for example, from an endocrinologist, a geneticist and related specialists but depends on the symptoms of the individual.

Etiology

In XX females who are normal, one of the X chromosomes is inherited from the mother and the other from the father. Parts of one of two X chromosomes are inactivated randomly in all somatic cells. Turner syndrome is caused by partial or complete loss of one copy of the X chromosome. It is a defect that is structural in one of the X chromosomes, and mosaicism of a 45. This happens between an X cell line and another. This depends on the karyotype, and the phenotype expression can be variable in an extreme way. Turner syndrome monosomic females never have to inactivate their X chromosome, which is single.

There are problems that come from only one single copy of the X chromosome. Out of the 50% cases of TS one of the X chromosomes is inherited from the nondisjunction that happens during parental gametogenesis. It leaves a monosomy of X genotype in the fetus. 70% to 80% of females who are monosomic, the single X chromosome originates from the mother with the other being from the father. There are risk factors though as the female phenotype does not seem to have dependence on the original parent of X chromosome. There is no appearance of imprinting as a factor in this syndrome.

Of the Turner syndrome monosomic females, 5% to 10% to be approximate, have an X isochrome, which comes from duplication of one X chromosomes' long arm as the X chromosome and short arm are lost. What mostly remains of the TS karyotypes, show a form of mosaicism, with both a normal cell line and a monosomic often involves an isochromosome. In most cases, mosaicism comes from nondisjunction of the postyzygot.

TS females have a presentation of heterogeneous phenotype and often diagnosis is done long after birth, this is when amenorrhea, primary or secondary in nature presents in adulthood or adolescence. Women with an X chromosome ring, are likely to have cognitive impairments and symptom of early menopause during adolescence after spontaneous menstruation but may have fewer typical congenital abnormalities of TS.

Incidence

An approximate of 1 of 2000 to 3000 girls born alive have TS. The majority of 45 in  the first semester are aborted simultaneously of the X fetuses. Theory has it that the 45, X karyotype is present in 3% of conceptions but 99% of these fetuses that are abnormal spontaneously abort during the first pregnancy trimester. This accounts for a 7% to 10% of spontaneous abortions. Fetuses that have the X monosomy chromosomes that do not abort spontaneously during the first trimester, are presented in the second and third trimesters. This comes with severe lymphdema, hydrops fetalis or cystic hygromas, which associates itself with fatal death rates that are high.     

Pathophysiology

Obstruction of the lymph during fetal development of females with TS typically have  a wedded neck, downward slanting of the eyes, low posterior hairline,  ear rotation of the posterior and, epicanthal folds. Skeletal features in TS females have mandible alterations and cranial base. Congenital hip dislocation is common in infants who have TS and contribute to developed hip arthritis in females who are older. Females with TS have relatively longer hand lengths than those that don't have TS.  They tend to have a shield-shaped chest, internipple space, stocky legs that are short and, a torso that is square shaped.

In the lymphatic structures, TS females have acral congenital lymphedema, neck folds that are redundant and pterygium coli. This happens during the seventh week of gestation when the X chromosome is deleted. In bone structural defects they have characteristics that include, short legs that are disproportional, upper to lower segment ratio is abnormal, nipples widely spaced, a short neck, scoliosis, and a chest that is square shaped. In the endocrine system, ovarian failure occurs after the age of 10. The thyroid adrenal function of females who have TS have incidence of hypothyroidism, it starts at the age of 10 and increases with age. In gastrointestinal, infants have tongue movements that are dysfunctional, poor chewing skills and hypotonia marked at the lips and cheeks.

In cardiovascular structures, females with TS have defects like pericardial effusion, defects of conduction, aorta rupture, regurgitation of the aorta, dissection, prolapse of the valve and systematic hypertension. Heart defects are detected through prenatal ultrasound. In renal structure the TS female may have horseshoe kidneys, renal vascular supply that is abnormal, obstruction, and a double collecting system. These structural abnormalities happen when doing an ultrasound.

Assessment

It is often unlikely for a girl to have all associated features of Turner syndrome. There are different presentations of the syndrome; it is partly responsible for the difference in the ages at which diagnosis is made. Diagnosis in the utero mostly takes place following investigation for reasons such as maternal age. In this age most women are given chorionic vilus sampling (CVS) to be able to diagnose other known age related genetic syndrome in mothers. Detection of a cystic hygroma, subcateneous edema that is severe, increased nuchal translucency, short femurs, hydrops fetalis or an aortic arch that is narrowed during a routine prenatal ultrasound, may lead to TS fetus suspicion. An approximate of half the girls with Turner syndrome are diagnosed at birth, infancy period, or in early childhood, with an average age of 6.6 years of all diagnoses.

Lymphedema, manifests itself as puffy feet and hands, absent or delayed puberty and also short stature are the key indicators in many cases. Diagnosis during infancy that should lead to analysis of chromosomes, are typical clinical features for example, aorta coarctation, feet and hands lymphedema, webbed neck and a cardiac condition that is related specifically to TS. Spitting frequently, latching and sucking difficulty, vomiting, thriving failure and gastrointestinal reflux are other abnormalities that are less specific. They are mostly caused by oropharynx anatomical abnormalities. Features that are less distinct and shown with forms of mosaic of TS means that diagnosis may be delayed until later on when then the children are identified as failing to progress into puberty, short stature and poor growth.

The main features that begin in utero and persist on after birth is short stature (Cave et al 2003). Reports have said that newborns are approximately 3cms shorter than babies that do not have TS. In the third year of life, there is an often slow down in the growth and in preschool period, short stature is seen which is a trigger for referral to a pediatrician and regularly to pediatric endocrinologist. The final height of girls who are have TS, is an approximate of 142cms, which is short of 21cms of females that do not have TS (Donaldson et al 2006). There is typical familiarity by pediatricians with physical characteristics of TS that are most common and have the ability to suspect the syndrome. The patients present a growth deficiency, hands and feet lymphedema, gonadal dysgenesis, delay in puberty, ptetrygium colli and cubitus valgus.

However many TS females do not have features that are distinctive and have a normal appearance physically with short stature related to family background.

Diagnosis

Girls, who have Turner syndrome, are attracting increased medical attention because of prenatal diagnosis done by chorionic villus sampling or amniocentesis. Sometimes these studies have been done due to suggestive features of diagnosis, identified by ultrasonography. Diagnosis of other girls with TS is done incidentally by studies undertaken for abnormal maternal serum and maternal age screening results. There should be a repeated study on postnatal blood sample from newborns, if prenatal karyotype has been done through chorionic villous sampling and amniocenthesis. Sex chromosome anomalies testing, including testing may have to be part of the new born screen. This is because, with other conditions that have been screened currently, the pediatrician is involved in conveying the results received to the parents of affected girls. The anomalies of TS were believed to be primarily limited to the left outflow tract, but studies recently undertaken using magnetic resonance imaging (MRI), have suggested that anomalies of the cardiovascular spectrum is broader. Baseline MRI should be undertaken in all girls that have TS when procedure is performed without sedation. Those patients with blood pressure should undergo imaging for monitoring aortic size periodically.  

Management

Management of the condition using a multidisciplinary approach under a pediatrician enndocrinologist direction is mostly advocated by support groups and health professionals (Seanger et al 2001). Two management aspects are used, hormone growth for short stature and puberty induction. Management of short stature with growth hormone (GH) is administered at night subcutaneously. Its efficiency is influenced by factors like individual response, expectations of the parent and the child, and adherence to the treatment plan. There has been debates as to the optimum age to start the growth hormone varies with clinical practice on which age the injections should be administered. It is advocated by Donaldson et al (2006) that a when a child starts going to school at four or five years old, there is little evidence to have suggestions that there will improvement in height starting at three or two years old.  This is important due to the length of time of injections required by the children. When the patients are younger, they may not be willing to have the injections as they don't understand treatment rationale. As appearance and image of the body become important, treatment adherence motivation is increasingly high.

Turner syndrome girls have a normal vagina and can have sexual relationships. Over 90% of these girls have failure of the ovary and require puberty induction. Induction has to be timed to enable growth to the maximum but should also be in line with the girl's age. Oestrogen therapy is given for development of sexual characteristics, later progesterone is usually added to have monthly menstrual established. Prediction of final adult height comes from menarche height. Oestrogen use for puberty induction induces epiphyses fusion and acts as factor which limits longitudinal bone growth. If growth is a priority, maybe due to late diagnosis, that would delay induction of puberty.

Some girls with TS have ovaries that function but few progress and sustain without any assistance through puberty. There is impact on transitional care during induction of puberty and the girls remain at the pediatric services location until puberty is complete. Seanger et al (2001) recommended involvement of gynaecologists and endocrinologists during the transition period to give advice on issues related to fertility.  Orthopedic treatment can be an intervention for skeletal problems that are severe. Normalized development can be helped by growth hormones and estrogen replacement therapies if initiated well before puberty is completed. These therapies are likely to help prevent osteoporotic fractures if there is an increased risk of the patient. If scoliosis is recognized earlier bracing can help avoid spine developmental deformities. Patients with cardiac malformations before surgical or dental procedures are done because these structural changes can lead to endocarditis.

Nursing Care

Girls are not regularly hospitalized when they have this condition, but have impact that is significant on the day to day lives and also long term psychological and physical health. The implications are long life and the girls will have to use medical health services their entire lifespan from childhood, through adolescence and adult lives. There is change in the priorities and concerns of parents and the girls at different ages in their development. They need practical and emotional support from nurses who are specialized with knowledge and experience of child development and difficulties associated with TS. In infancy issues that relate to poor feeding, poor sleeping and cardiac abnormality may be evident (Turner Syndrome Support

Society 2002). TS girls are reported to have cardiac abnormalities and require advice on prophylaxis for endorcarditis and also monitoring, some even require cardiac surgery.

Problems in feeding result to poor weight gain, help from speech therapists and dieticians may be need until the girls preschool years. In preschool, girls are reported to have behavior difficulties and high levels of activity. Parents can be involved about support groups and put them in touch with parents of other patients to share experiences. This may help with practical solutions, advice, and guidance. TS girls have problems with the ears that require repeated surgical and medical interventions. ENT specialists insert grommets, mastoidectomy or adeno-tonsillectomy (Donaldson et al 2006). Infection of the middle ear may lead to conducive deafness and audiology assessment should be regular due to incidence of sensorineural hearing loss.

It may be a problem in adulthood as it is progressive. Oedematous feet and hands and to minimise problems of foot structure and infection from toe nails involution, referral to a podiatrist is necessary (TSSS 2002). The school age group focuses on social development and learning needs. There are problems noticed in learning as visuospatial awareness and mathematics. Socially TS girls misinterpret social cues of peers and respond inappropriately. There is change in physical experiences during adolescence, in TS girls these changes do not take place and need help manage the events.        

The role of the specialist nurse includes educating the child and family about all aspects of storing and administering growth hormone treatment as well as its effects. Explanation is needed on the benefits and limitations of several devices available for the administration of GH to support the family in selecting the most appropriate for them. Nurse specialists in pediatric endocrinology have knowledge and the expertise to support needs that are specific to the girls and the parents and family that follow TS diagnosis. They provide support for healthcare professionals who may engage in different developmental stages with the families. The nurses have an understanding of the condition which is multifaceted in nature. TS management and impact is essential for all the nurses that care for the children. This may be essential when they come into contact with TS girls who have other related health issues.

Patient and Family Resources

Issues relating to friendships, family relationships, and trust for health professionals are themes that are central to chronic illness. There is tendency to treat girls who are tall to be treated as if they are older and vice versa. There are lower expectations from adults of expectations from the children and opportunities are limited for development and independence in skills of living which threatens their autonomy sense (Erling 2004).

Self care is essential in development and enhances their self esteem. Children take additional responsibilities as they move through tasks that are developmental of adolescence is complex. Specifics on issues of turner syndrome girls are not well understood. Girls with Turner syndrome are less involved in social interaction with their peers and may lead to socially isolating themselves. Social and organizational skills, self confidence and emotional support are the main issues to be considered in promotion of self care and foster independence.

It is important for adolescents to prepare well and be the role of decision maker in her health care. At the age of 12 years, care focus should move from the parent to the girl herself. Pediatrician should have dialogues with the adolescent who has ST on maintaining healthy weight for the weigh and good dietary habits. Heart healthy exercises should be incorporated into their routine daily. Family planning options can also be discussed with adolescents in time such as egg donations. Education of the adolescent should be done to take precautions that are appropriate. Transition preparations should be completed with adult clinicians to ensure continuity of care into adulthood that is appropriate. Pediatricians can help identify adult practitioners who have interest in care for TS patient who need multiple needs in health care.