Symptoms, cause and therapy of the hereditary disease

Symptoms, cause and therapy of the hereditary disease

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Children with Noonan syndrome often have widely spaced eyes

Noonan syndrome affects 80,000 people in Germany. Hereditary disease is the second most common hereditary disease that leads to a heart defect after Down syndrome.Noonan syndrome (NS) is one of the most common genetic diseases. According to the Children’s Network e.V., the syndrome occurs in one in 1,000 births. The real figure, however, could be much higher. If the typical symptoms of NS are poor, they often go undetected. It is NS is the second most common genetic cause that leads to cardiac malformations.

What does Noonan mean?

Noonan syndrome is named after the United States Pediatric cardiologist Jaqueline Anne Noonan. She was the first to describe the clinical picture of hereditary disease in 1963. Jaqueline Noonan also described Hypoplastic Left Heart Syndrome (HLHS).

The 89-year-old cardiologist is considered one of the best doctors in the United States.

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What is the cause of Noonan syndrome?

Noonan syndrome is an inherited disorder that can affect both girls and boys. A mutation of the PTPN11 gene (tyrosine protein phosphatase non-receptor type 11) was detected in affected individuals. This gene plays e.g. a role in growth: many Noonan patients are short. This gene mutation can be inherited (autosomal dominant) or can arise accidentally. In the case of inheritance, it is more often the mother than the father (ratio 3: 1) who inherits Noonan syndrome.

The exact causes of Noonan syndrome have not yet been fully clarified. Preventing Noonan syndrome is not (yet) possible.

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What are the symptoms of Noonan syndrome?

Prenatal diagnosis can be used to diagnose Noonan syndrome before birth. A third of all NS patients have mild intellectual disabilities (IQ between 69 and 82), about 50 percent of all NS patients have delayed growth (average height at birth: 47 centimeters).

In fact, diagnosis of Noonan syndrome is difficult. There is no uniform appearance of NS, the “typical” symptoms can occur, but do not have to. In addition, the characteristics are different for each patient.

According to the children’s network, the personality traits can be described as follows: “Many of the Noonan children are described by their parents as ‘difficult’, behavioral and very stubborn in their behavior. Social skills are often particularly well developed in Noonan children. The children are warm, kind and very concerned about the well-being of others.

Nevertheless, doctors and scientists have the characteristic features of Noonan syndrome defined as follows:

Characteristic facial features of Noonan syndrome patients

  • wide eye relief
  • drooping upper eyelid
  • Indentation in the middle of the upper lip
  • oblique eyelid axis
  • broad, flat bridge of the nose
  • high arched palate
  • narrow jaw
  • little chin
  • Misaligned teeth
  • increased tendency to caries
  • deep-seated ears
  • short, wide neck
  • additional neck fold

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Heart defects in Noonan syndrome patients

  • Pulmonary stenosis atrial septal defect
  • Hypertrophic cardiomyopathy
  • Other heart defects

Muscle and skeletal system of Noonan syndrome patients

  • Abnormality of the chest
  • Tendency to scoliosis
  • Weakening of muscle tone
  • Muscle hypotension
  • Delayed bone age
  • Short stature

Eating disorders (in infancy and early childhood of Noonan syndrome patients)

  • Poor suction
  • Frequent vomiting
  • Tube feeding
  • Failure to thrive

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Delayed development of Noonan syndrome patients

  • Learn to sit and walk
  • Language development
  • teething
  • Change of teeth
  • Onset of puberty
  • cognitive development
  • Sometimes learning disabilities and poor performance
  • Mental retardation in about a third of Noonan’s patients

Other symptoms in Noonan syndrome patients

  • Visual impairment
  • Hearing loss
  • Blood clotting disorders
  • Undescended testicles in boys
  • Kidney malformations
  • Lymphatic system disorders (e.g. lymphedema)

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This is what patients with Noonan syndrome look like

A video of the Noonan Syndrome Foundation:

How to treat Noonan syndrome

Noonan syndrome is not (yet) curable. Only the symptoms are treated – primarily the heart defects of NS patients. Heart valve surgery is often required.

Surgical treatment of the skin fold between the head and neck can also be treated. You can also Medications such as growth hormones or beta blockers Noonan patients are prescribed for therapeutic purposes.

Speech errors can with the help of a speech therapist be alleviated, visual and hearing difficulties with glasses or hearing aids. Learning problems can be caused by Early intervention, occupational therapy and physiotherapy be improved.

More information about Noonan syndrome is available at

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