He Turner's syndrome ( St ) Is a genetic pathology associated with the female sex that occurs as a consequence of the Partial or total absence of an X chromosome in all or part of the body's cells (National Organization for Rare Disorders, 2012).
The most frequent clinical features usually include reduced height or height, gonadal dysfunction, various cardiac malformations, alterations Ophthalmology and optics among other features (Genetics Science Learning Center -University of Utah, 2016).
Turner syndrome is usually not associated with the presence of mental retardation, intellectual development is normal, except in specific cases. However, it is Frequently observe a particular neurocognitive profile (Ríos Orbañanos et a., 2015).
The diagnosis of this pathology can be made during the gestation phase, based on clinical observations. Thus, when there is a suspicion A genetic study should be performed. However, it is more often done in the first moments of life or during childhood (National Organization for Rare Disorders, 2012).
Although there is no curative medical intervention for Turner syndrome, numerous specialized treatments have been designed for the Treatment of medical complications of this pathology: hormonal treatment, plastic surgery, nutritional control, stimulation Neuropsychological, etc. (Galán Gómez, 2016).
Turner's syndrome is not a deadly pathology; however, the development of serious medical complications such as cardiac abnormalities can put the Risk of the survival of affected individuals (Genetics Home Reference, 2016).
Characteristics of Turner's Syndrome
Turner syndrome (ST) is named after the physician Henry Turner, who was one of the first medical specialists to describe the clinical course of this syndrome Pathology in the medical literature, circa 1938 (National Organization for Rare Disorders, 2012).
In addition, this medical condition is also known as Ullrich-Turner or Bonnevie-Ullrich, Turner, and / or gonadal digestion (Turner Syndrome Foundation, 2016).
Generally, this pathology is not considered a disease, but a syndrome, that is, a set of signs and symptoms that relate to each other, Allowing a grouping, but not necessarily all occur at once in a case (Lopez Siguero, 2016).
Although ST has a well-defined clinical course, it can cause a wide variety of medical problems Genetic etiological alteration (Mayo Clinic, 2014).
Karyotype
Since 1959 it is known that this pathology affects specifically the female sex, since it was observed that Turner syndrome occurs As a result of a total or partial absence of the X chromosome (López Siguero, 2016).
Humans have 46 chromosomes, organized at a structural level in 23 pairs. In addition, within these, we have two chromosomes that will define Our sexual traits.
Specifically, the male sex chromosome pair consists of an X and Y chromosome, whereas the female sex chromosome pair Is formed by two X chromosomes.
The combination and division of all this genetic material will determine our physical, cognitive and sexual characteristics. However, if during the In the embryonic development stage a failure occurs in the cell division that affects part or all of an X chromosome, the Turner syndrome (Association of Anomalies and Dentofacial Malformations, 2012).
In summary, the karyotype of Tuerner syndrome presents 45 chromosomes with a model of 45 X, an absent sex chromosome.
The expression of the abnormalities produced by Turner syndrome usually varies according to the level of development of the affected person, therefore, We may find more frequent clinical features in some stages than in others.
In addition, Turner's syndrome is associated with high morbidity, so it may appear along with other medical conditions such as diseases Cardiovascular, diabetes , Hypothyroidism , etc. (Ríos Orbañanos et al., 2015).
About us
Turner syndrome (ST) is a medical condition that develops in about 1 person for every 2,500 girls born alive around the world (Genetics Home Reference, 2016).
However, the magnitude of the disease may vary, since it is common for spontaneous and involuntary miscarriages to occur (Genetics Home Reference, 2016).
The Turner Syndrome Society of the United States (2015) notes that Turner syndrome can occur in approximately 10% of abortion cases involuntary.
Specifically, it has been estimated that more than 70,000 women and girls with this syndrome live in the United States (National Organization for Rare Disorders, 2012).
Regarding the distribution by sex, we have previously pointed out that, Turner syndrome is a pathology that specifically affects sex female. In addition, no cases have been identified associated with particular ethical or racial groups, or specific geographic regions.
On the other hand, TS is a pathology of congenital genetic origin, so the physical phenotype is present from the moment of Birth, although the symptoms may be subtle in many cases.
Thus, ST is usually diagnosed before birth or shortly thereafter. However, there are very mild cases that can remain without Diagnose all childhood, even in adulthood (National Organization for Rare Disorders, 2012).
Signs and symptoms
Depending on the specific genetic alteration of the X chromosome, ST can cause differential clinical traits among those affected, However, some of the most common ones have been pointed out (Galán Gómez, 2016):
Musculoskeletal Disorders
- Short stature : Although in the early stages of life the development of height usually conforms to the standards of Growth, it has been observed that those affected usually reach a final below-average height. From birth and Early stages of childhood, growth slows down, becoming slower in comparison are their age group. In addition, they do not Burst of growth during puberty.
- Reduced collar : The neck usually has a shorter length than usual, accompanied by the presence of skin folds.
- Cubito Valgo: Is a structural malformation affecting the forearm. In particular, a deviation from Outside, with the elbows semi-flexed permanently.
- Reduction of metacarpals : he metacarpus , One of the bony pieces that make up the structure of the fingers of the hand, usually Present a smaller size than usual or expected.
- Malformation of Madelung : Is an alteration that affects the structural composition of the wrist. This is shorter than Normal and with an arcuate arrangement of the ulna and radius, significantly reducing mobility.
- Scoliosis : Like all other musculoskeletal disorders, it is common to observe a deviation or curvature of the spine Vertebral in the people affected by this syndrome.
- Genu valgo : This condition is also called Legs in"X" , Since they are deviated, observing a position in which the Knees come to touch. The legs are positioned to pierce and the ankles are reviewed.
- Micrognathia and ogival palate : It is possible the development of a mandible with a reduced dimension, accompanied by an elevation and Bowing of the central portion of the hard palate.
- Hypoplastic nipples : In women with ST, the breasts are usually poorly developed.
Lymphatic disorders
In the case of these alterations, the most frequent is to observe a Lymphatic obstruction , Ie a blockage or blockage of the drained liquid from the Different body tissues through the lymphatic vessels.
When this occurs, various anomalies can develop, the most common in ST are:
- Pterigium Colli : This alteration is a cervical malformation that affects the structure of the neck, in which the Presence of membranes or bands of muscle tissue and fibers, running from the mastoid to the shoulder.
- Low capillary implantation line : It is common for the hair implantation line to be placed at a low level. Specially in The cases that appear Pterygium Colli .
- Edema in extremities : The alteration in the lymphatic circulation can cause the accumulation of liquid in diverse areas Body, especially in the hands and feet, leading to development of significant inflammation.
- Dysplasia of ungueal: Is a type of dystrophy that affects the nails, these usually present a loss of structural volume, stretch marks Longitudinal and loss of enamel.
- Dermatoglyphs : Includes the development of cutaneous ridges on the palms of the hands or feet.
Germ cell disorders
- Gonadal anomaly: Ovarian insufficiency usually appears and the external genital organs usually develop incompletely or partial. In many cases, this type of alteration is designated as"sexual infantilism"in the medical literature.
- Infertility: The absence of hormonal and sexual production by the ovaries, imply a poor development of puberty. TO In addition to poor development of secondary sexual characteristics, women often lack egg production capacity
And menstruation.
Neuropsychological pattern
ST does not usually imply the development of a general intellectual deficit. The people affected present an intelligence adjusted to their Age and level of development.
However, at the cognitive level, several areas with a more deficient development have been detected, which affect in a global way the capacity of learning.
Many affected often have problems with the development of directionality and orientation, memory and attentional skills or the capacity of Problem resolution .
Other common alterations
- Cardiac abnormalities: Congenital heart defects such as Bicuspid aortic valve Or the shortening of The aorta.
- Renal anomalies: Horseshoe kidneys, malformations in the urinary tract, are some of the most common renal manifestations.
- Eye and visual anomalies: Usually observed squint , Amblyopia or drooping eyelids, among other types of alterations.
- Auditory abnormalities: The ears and the external auditory canal usually has a low disposition, in addition the development of another type of Internal malformations can cause a significant reduction of the hearing capacity.
Causes
As we noted earlier, the development of Turner syndrome is due to the presence of a genetic anomaly on an X chromosome.
During the gestation phase, when the genetic material is reorganized to start up all the biochemical processes of development Embryonic, can occur several alterations or errors, the result of internal factors, external factors or random mutations.
When this happens, the functional structure of the chromosomal and genetic material of the individual can be altered, and consequently, the phenotypic and Behavioral disorders.
In ST, we describe a clinical pattern that specifically affects women, this is due to X chromosome abnormality.
Although, both sexes, men and women we have an X chromosome, in the case of the women this one doubles. Therefore, when an anomaly develops that Partially or totally affects the presence of an X chromosome, the gestation of a male embryo is interrupted spontaneously, since due to Its sexual chromosomal composition (XY), this situation will not allow it to develop with the unique presence of the Y chromosome .
However, in the case of the partial or total absence of an X chromosome in a female embryo, this fetus may be viable, since the absence of This chromosome can be compensated for by the other X component of the pair, because women have a sex chromosomal composition X X.
The X chromosome is not symmetrical, it has some arms (p) and long arms called (q). When there is a partial or total loss of one Of the arms, differential signs and symptoms may appear in people with Turner's syndrome (Galán Gómez, 2016).
When the short area of the X chromosome remains preserved, those affected may show a normal development of puberty. This occurs around the 10-15% of cases, while, if the arm is kept longer, the most characteristic sign will be the reduction of height (Galán Gómez, 2016).
Aside from this, the most common in Turner's syndrome is the total absence of an X chromosome, which will give rise to the presentation of the clinical course Complete (Galán Gómez, 2016).
Diagnosis
Usually, the diagnosis is made in the prenatal stage. Ultrasound ultrasounds are able to show some of the physical anomalies Which produces the ST.
Thus, when there is a suspicion of this pathology, a genetic study is usually carried out to evaluate the DNA Fetal (Mayo Clinic, 2014).
Lab tests are usually used at this stage: chorionic villus sampling and amniocentesis attempt to extract a Portion of placental tissue and amniotic fluid , Respectively, to analyze their chromosome composition (Mayo Clinic, 2014).
However, if the clinical suspicion does not begin until the post-birth phase, the genetic study is usually performed through the extraction of A small blood sample.
In addition to determining the presence of etiological genetic abnormality, it is essential that different specialists evaluate the particular characteristics Which presents the person affected, as well as the underlying medical complications (Mayo Clinic, 2014).
The essential goal of clinical exploration is to design an uncivilized and effective intervention.
Treatment
Although there is no curative measure for Turner syndrome, there are several therapeutic strategies for the treatment of signs and symptoms Characteristic of this pathology.
Some of the most frequent specific approaches include (Galán Gómez, 2016):
- Pharmacological treatment for hypertension and cardiac disorders.
- Compensatory tools for cases of Hearing loss .
- Hormonal treatment, based on the administration of Estrogens To stimulate the development of secondary sexual characteristics.
- Administration of Growth hormone (GH), for the stimulation of increase of the size.
- Nutritional regulation for the control and regulation of body weight.
- Early stimulation and neuropsychological treatment for intervention in the most deficient cognitive areas.
References
- AAMADE. (2012). Turner's Syndrome . Obtained from Association of Dentofacial Anomalies and Malformations.
- Galán Gómez, E. (2016). Turner's syndrome. Spanish Association of Pediatrics .
- Galindo, A., Masero, A., González, C., Fernández, F., & de la Fuente, P. (2005). Prenatal Characteristics of Turner Syndrome. Prog Obstet Ginecol. , 421-429.
- Genetic Science Learning Center. (2016). Turner Syndrome . Retrieved from the Genetic Science Learning Center. University of Utah.
- López Siguero, J. (2016). Questions and Answers about Turner Syndrome. Spanish Association of Pediatric Endocrinology .
- Mayo Clinic. (2014). Turner syndrome . Obtained from Mayo Clinic.
- NIH. (2013). Learning About Turner Syndrome . Retrieved from What is Turner syndrome?.
- NIH. (2016). Turner syndrome . Retrieved from the Genetics Home Reference.
- NORD. (2012). Turner Syndrome . Retrieved from the National Organization for Rare Disorders.
- Ríos Orbañanos, I., Vela Desojo, A., Martínez-Indart, L., Grau Bolado, G., Rodríguez Estevez, A., & Rica Echevarria, I. (2015). Turner's syndrome: from Birth to adulthood. . Endocrinol Nutr. , 499-506.
- Turner Syndrome Society of the United States. (2016). About Turner Syndrome . Retrieved from the Turner Syndrome Society of the United States.