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 manner in which our physical growth and development occurs… and even a part of our intellect and personality is inherited from our ancestors.

However, sometimes genes suffer mutations that, although they may sometimes be harmless or even positive, sometimes have severe repercussions that hinder, to a greater or lesser extent, the development and ability to adapt to the environment of those who suffer from it. One of these genetic disorders is Noonan syndrome.

Noonan syndrome

Noonan syndrome is a relatively common genetic disorder that occurs in one in every one to two thousand five hundred births, with a prevalence similar to that of Down syndrome. Is about a disease whose symptoms can be highly 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 rate of growth in these children, although initially it seems normative, is severely slowed, and they usually present short stature and psychomotor delays. This problem becomes especially evident in adolescence. Sometimes it occurs together with intellectual disability, although this is usually mild. Sensory may present vision and hearing problems such as strabismus or recurrent otitis.

At a morphological level, facial alterations such as ocular hypertelorism (the eyes are excessively separated from each other), drooping eyelids, low and rotated ears, and short neck are seen from birth. It is also common for them to present bone alterations in the form of a deformity in the thoracic cage (which can appear in the form of a sunken chest in the area of ​​the sternum or pectus excavatum or in its profusion or pectus carinatum).

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One of the most dangerous symptoms is the presence in most patients of congenital heart diseases such as pulmonary stenosis or hypertrophic cardiomyopathy, as well as other vascular problems. In addition, the presence of hemorrhagic diathesis is common in more than half of the patients, which entails great difficulties in coagulation, which means that great caution must be taken when suffering from hemorrhages. They are also very prone to bruising.

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

In the genitourinary system alterations such as cryptorchidism may appear or no descent of the testicles in men. This causes fertility problems in some cases. However, in the case of women there are usually no alterations in terms 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 has been found in the presence of mutations on chromosome 12. Specifically, alterations appear in the form of 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 that participate in the growth of cells and their development, so their alteration causes various alterations in different systems of the body.

In general, it is considered an autosomal dominant disorder that can be inherited from parents to children (transmission from the mother being more common), although sometimes the mutations that generate Noonan syndrome appear without any of the parents having it. transmitted or there are other cases in the family.

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There is currently no curative treatment for Noonan syndrome with existing treatments dedicated to alleviating symptoms, preventing complications, intervening on structural and morphological anomalies, optimizing their capabilities and offering these people the best possible quality of life.

For this purpose, a multidisciplinary methodology is used with the intervention of different professionals from both medicine and other sciences The symptoms and alterations presented by those who suffer from this disease can be very variable, so the treatment will depend on the type of alterations they suffer from.

In Noonan syndrome, it is essential to periodically control and monitor the subject’s health status, especially in the likely presence of heart disease. Coagulation problems are not strange in this syndrome, so this fact must be taken into account when carrying out possible surgical interventions. During the first years, it may be necessary to use tubes to feed the child. It is not strange that growth hormone treatment is used, so that the development of the child is favored.

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

Finally, genetic counseling must be taken into account once the subject reaches adolescence or adulthood due to the possibility of transmission of the disorder.

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

As long as possible complications are controlled, people with Noonan syndrome can have a standard of living equivalent to that of other people without this disorder. It is possible that some of the symptoms become less with age as they become adults.