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What is Noonan Syndrome ?

Noonan syndrome is an inherited condition that causes abnormal development in several regions of the body. Individuals affected by Noonan syndrome may show a number of deficits such as irregular facial features, cardiac abnormalities, stunted growth and other physical defects, as also diminished intelligence.

Noonan syndrome has a dominant inheritance as its cause and can develop when a copy of a mutated gene is passed on to the fetus from a parent. The gene mutation can also be spontaneous, wherein it can occur without any family history of the disease.

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There is no special treatment for Noonan syndrome. It is primarily aimed at dealing with and effectively managing the complications and symptoms of the condition. The short stature may be treated with the use of growth hormones

Noonan syndrome symptoms

  • A majority of the patients of Noonan syndrome are affected by various symptoms of congenital cardiac disease. Some of them include:
    • The heart muscles may elicit irregular growth and become thicker. It affects around 20 % of those with Noonan syndrome
    • Valve disorders such as narrowing of the pulmonary valve that delivers blood to the lungs is one of the most common heart disorders associated with Noonan syndrome
    • Noonan syndrome may also be accompanied by various structural defects of the heart such as narrowing of the arteries that supply blood to lungs for oxygen, and presence of a hole in the cardiac wall that distinguishes the two lower heart chambers
    • There are several distinctive facial characteristics that are unique to patients affected by Noonan syndrome. They include:
      • A baby that is just about a month old may have low-set ears, low-slanting and wide set eyes, a small neck, wide peaks and a deep groove may be present on the upper lip and the back of the head may have low hairline
      • In childhood, the Noonan syndrome child may have deficient facial expression
      • The face of the adolescent may have sharper facial features with a wide forehead and a tapering chin, less prominent eyes, and very visible neck muscles or a long neck with additional skin folds
      • Adults with Noonan syndrome may have wrinkled skin which appears more translucent. The line that runs from the edges of the nose to the corners of the mouth may also be more prominent
      • Noonan syndrome patients may also elicit musculoskeletal problems such as a raised chest or a sunken chest which has an abnormal appearance to it. The nipple may be wide set and the neck may have many folds of skin as discussed above.
      • A child with Noonan syndrome will have normal birth weight. Due to feeding difficulties, there may be poor weight gain till 18 months. Bone maturity is generally delayed due to Noonan syndrome, and hence teens may not elicit the growth spurt. But such individuals may tend to experience growth into the twenties. Around 1/3rd of the patients grow to a normal height, while the rest may still be short in stature.
      • In rare cases, the patients may have lowered intelligence which may pose learning difficulties. Special education may be required for such individuals affected by Noonan syndrome. Most patients tend to complete schooling and college and go on to have careers.
      • A majority of the patients affected by Noonan syndrome tend to be more vulnerable to hemorrhage and can easily bruise and bleed.
      • One of the most common symptoms of Noonan syndrome is the presence of abnormalities of the eyes and the eyelids. Affected individuals may elicit farsightedness, nearsightedness, problems of the eye nerves and eye muscles, and rapid eyeball movements. The eyes may differ in size and shape, and the iris may be green or pale blue in color.
      • There may be problems of the lymphatic system that may affect the entire body or may be isolated to a particular area, most common being the collection of fluid on the top of the feet or the back of the hands
      • Patients may have skin and hair problems wherein the texture and color of skin may be different and there may be little, coarse and curly hair.
      • People with Noonan syndrome may also experience kidney and genital problems. Puberty may be late for both boys and girls. Males may be affected by undescended testicles at birth which may cause fertility issues. Females have normal fertility levels. Some men and women may elicit signs of kidney problems

Causes of Noonan Syndrome

  • Mutations of a particular gene can result in the development of Noonan syndrome. The doctors are currently aware of seven different types of gene mutations that can result in the condition. However, it can also be caused by mutation of a gene other than the seven known ones.
  • The gene mutation may be passed on by any one of the parents to the child. It can also develop as a fresh mutation in the child itself.
  • The risk to developing Noonan syndrome increases by nearly fifty percent if any one of the parents has the condition.

Noonan Syndrome Treatment

Treatment of Noonan syndrome is focused at managing the symptoms. They include:

  • The growth rate may be treated as per the causes. In case of low levels of hormones, the patient may be given growth hormones
  • Certain drugs as well surgery is used to correct the heart abnormalities
  • Learning disabilities and other behavioral and cognitive deficits may be treated via many therapies, such as speech and physical therapies.
  • Blood clotting medications may be recommended for easy bleeding and bruising
  • The use of glasses, surgery, etc. may be advised for vision problems
  • Kidney and genital problems may be treated via surgery or any other method as deemed correct b y the doctor. Testosterone replacement may also be tried.
  • Draining of excess fluid and use of medications may be recommended for problems of the lymphatic system.


Noonan Syndrome life expectancy

The life expectancy of a child or person with Noonan Syndrome is dependent on early diagnosis and medical intervention. Management of cardiovascular complications is the key.   With progress in the area of surgical technology, the Noonan syndrome life expectancy is becoming as normal as that of an average person.


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