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Noonan syndrome: causes, symptoms and treatment

by Alivia Nyhan
Published: Last Updated on

The Noonan syndrome is a hereditary disease, i.e., it is transmitted from parents to children. It is called a syndrome because they are a complex and multifaceted set of symptoms and signs with a genetic cause. The direct cause of this pathology is an alteration in the sequence of one of the copies of a gene, that is, a mutation. It is inherited in an autosomal dominant manner, which means that a person with this mutation will transmit it to 50% of their offspring.

The incidence of this disease is 1 in 1000 or 1 in 2,500 live newborns, being the most common cause of congenital heart disease. In this FastlyHealarticle, we explain Noonan syndrome’s causes, symptoms, and treatment.

Symptoms of Noonan syndrome

Patients diagnosed with Noonan syndrome present all or most of the following alterations:

  • A familiar face manifested with wide-set eyes, drooping eyelids, the downward inclination of the plane of the eyes, folds on the inner corner of the eye, a small chin, anteverted ears (blown), a short nose, and a wide neck.
  • Less than average weight and length.
  • Feeding problems, especially in the first years of life, vomiting, aversion to specific flavors, and difficulties with sucking or chewing are usually present.
  • Delayed puberty, pubertal onset two years later than usual.
  • Cardiac modifications present congenital heart disease in 80% of those affected because genetic mutations affect the normal development of the heart, causing alterations in the valves. These partitions separate their chambers or the muscular wall.
  • Cryptoquirdia absence of one or both testicles in the scrotal sac.
  • Edema is due to alterations in the lymphatic system, which occur with an accumulation of fluids between the body’s tissues, appearing as a swelling of the back of the feet and hands.
  • Alterations in vision, being myopia, astigmatism, and strabismus, are the most common.
  • Hearing loss as a consequence of different otitis media.
  • Abnormalities in the bones and muscles give rise to malformations in the thorax, such as the raised chest due to a sunken stern or the prominent sternum due to a deformity of the rib cage.

Causes of Noonan syndrome

As we have explained previously, Noonan syndrome is the result of a mutation, that is, a change in an individual’s genetic information that can be transmitted to their offspring. These defects can occur in four different genes (KRAS, PTPN11, RAF1, SOS1). The syndrome presents high clinical variability, implying that people who suffer from it have very different and varied expressions of the disorder, even if they belong to the same family. For this reason, not always when a mutation is identified in one of the genes that can be attributed to specific clinical manifestations.

Clinical tests and exams

Because the clinical manifestations are very varied, they affect many parts of the body and do not always appear in all patients; the diagnosis of this disease should be made by focusing on the different alterations:

  • Physical examination of possible facial alterations to determine if the patient presents the familiar face of the syndrome.
  • Specific assessments, for example, if there are signs of heart disease, perform an electrocardiogram or echocardiography and if there are signs of limited hearing, proceed to the appropriate hearing tests.
  • Genetic testing to identify mutations in the four genes that may be involved in the disorder.

Treatment of Noonan syndrome

There is no single treatment to alleviate this hereditary pathology. It is essential that people who present the symptoms of Noonan syndrome carry out periodic reviews to different specialist doctors, such as otorhinolaryngologists, cardiologists, among others. Everything will depend on the signs they present. Growth hormone has sometimes been used to treat the short stature that often occurs with this condition. Remember to always go to your doctor so that it is he who correctly diagnoses and treats any disease.

This article is merely informative. At FastlyHeal .com, we do not have the power to prescribe medical treatments or make any diagnosis. We invite you to see a doctor if you present any condition or discomfort.

If you want to read more articles similar to Noonan Syndrome: causes, symptoms, and treatment, we recommend that you enter our Genetic Disorders category.

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