Noonan syndrome: causes, symptoms and treatment

Much of who we are and how we are is given by our genetic code. The organization of our body, the pace and the way our growth and physical development occurs … and even part of our intellect and personality is inherited from our ancestors.

However, it happens that the genes undergo mutations which, even if they can sometimes be harmless or even positive, sometimes have serious repercussions which make the development and the capacity of adaptation to the environment of those who are more or less difficult. One of these genetic disorders is Noonan syndrome.

    Noonan syndrome

    Noonan syndrome is a relatively common genetic disorder that occurs in one in every thousand or two thousand births, with a prevalence similar to that of Down’s syndrome. This is a disease the symptoms can be very variable depending on the case, But which is characterized by the presence of alterations and delays in development, congenital heart disease, hemorrhagic diathesis and various morphological alterations.

    The growth rate of these children, although initially it seems normative, is greatly slowed down, and they usually exhibit short stature and psychomotor delays. This problem becomes particularly evident in adolescence. It sometimes occurs alongside a developmental disability, although it is usually mild. They may have problems with sensory vision and hearing such as recurrent strabismus or otitis.

    At the morphological level, the alterations of the face such as ocular hypertelorism (the eyes are too separated from each other), drooping eyelids, low and turned ears, short neck are seen from birth. It is also common to have bone alterations in the form of a deformity of the rib cage (which may appear as a sunken chest in the area of ​​the sternum or pectus excavatum or in its profusion or pectus carinatum) .

    One of the most dangerous symptoms is the presence in most patients of congenital heart disease such as pulmonary stenosis or hypertrophic cardiomyopathy, as well as other vascular problems. Likewise, the presence of hemorrhagic diathesis is frequent in more than half of the patients, which means great difficulties in the coagulation which generates that it is necessary to be very careful with the suffering of hemorrhages. They are also very easy to present with bruises.

    Although they are not that common, they can also have lymphatic problems which cause edema peripheral or even in the lungs and intestines. They also tend to be at higher risk for leukemia and other myeloproliferative problems.

    In the genitourinary tract alterations such as cryptorchidism can occur or no lowering of the testicles in men. This causes fertility problems in some cases. However, in the case of women, there is usually no impairment of their fertility.

    Causes of the syndrome

    Noonan syndrome is, as we have already said, a disorder of genetic origin, the main cause of which was found in the presence of mutations on chromosome 12. More precisely, alterations appear as a mutation in the PTPN11 gene in half of the cases, although other genes can also cause it – such as KRAS, RAF1 or SOS1. These are genes involved in the growth of cells and their development, so their alteration leads to various alterations in different systems of the body.

    It is generally considered to be an autosomal dominant disorder that can be inherited from father to child (mother-to-child transmission is more common), although the mutations that cause Noonan syndrome sometimes appear without either parent being aware of it. ‘transmitted. in the family.

    treatments

    There is currently no cure for Noonan syndrome, Being the existing treatments dedicated to relieving symptoms, preventing complications, intervening on structural and morphological abnormalities, optimizing their capacities and offering these people the best possible quality of life.

    A multidisciplinary methodology is used for this with the intervention of various professionals in medicine and other sciences. The symptoms and changes experienced by people with this condition can vary widely, so treatment will depend on the type of changes they have.

    In Noonan syndrome, it is essential to carry out regular control and monitoring of the subject’s state of health, especially in the presence of heart disease. Coagulation problems are not uncommon in this syndrome, so it should be taken into account when performing any surgeries. During the first years, it may be necessary to use catheters to feed the child. It is not uncommon for growth hormone therapy to be used to support a child’s development.

    At the psycho-educational level, given the high prevalence of learning problems and / or intellectual disabilities, it may be necessary the use of psychostimulation, Individualized plans at school, reinforcement of the learning of basic skills of daily life, speech therapy and the use of alternative and / or augmentative communication techniques such as the use of pictograms. Physiotherapy may be necessary to improve your motor skills.

    Finally, genetic counseling should be considered once the subject reaches adolescence or adulthood because of the possibility of transmission of the disorder.

    It may also be necessary to use psychological treatment for the subject, as feelings of inadequacy may appear. low self-esteem and depressive syndromes. Psychoeducation is also needed both for this and for the environment, and assistance to support groups could be helpful.

    Whenever possible complications are monitored, people with Noonan syndrome can have a standard of living equivalent to that of other people without the disorder. Some of the symptoms may go away with age as you get older.

      Bibliographical references:

      • Ali, O. and Donohoue, PA (2016). Noonan syndrome. A: Kliegman, RM; Stanton, BF; St. Geme, JW & Schor, NF (eds). Nelson Handbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier.
      • Ballesta, MJ and Guillén-Navarro, E. (2010). Noonan syndrome, pediatric diagnostic protocol; 1; 56-63. University Hospital of the Virgen de l’Arrixaca. Murcia.
      • Carcavilla, A .; Santome, JL; Galbis, L. and Ezquieta, B. (2013). Noonan syndrome. Rev.Esp.Endocrinol.Pediatr; 4 (suppl.). Gregorio Marañón General University Hospital. Gregorio Marañón Institute for Health Research. Madrid.

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