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Who Is At Risk For Noonan Syndrome & Is There A Blood Test For It?

Noonan syndrome is a hereditary disorder that influences progression and growth, musculoskeletal structure, the cardiovascular system, bleeding problems and malformations of the bones and the rib cage. In a nutshell, it impacts the individual in many areas of the body.

Noonan syndrome is triggered by variations in one of the numerous autosomal dominant protein sequences. The baby inherits the condition from the parent. There are also cases, where the individual acquires the condition through spontaneous mutation.

Who Is At The Risk Of Noonan Syndrome?

The signs and symptoms of Noonan syndrome can be subtle and is characterized by marked variable expressivity. Therefore, it becomes more complicated to diagnose the condition. Nevertheless, when you experience unusual facial features, heart problems, Malformation in normal growth, you should consider seeking medical attention. Based on your symptoms, you may be referred to a geneticist or cardiologist.

The prevalence is one in 1,000 to 2,500 live childbirths for acute phenotype, but benign occurrences may be as frequent as one in 100 live births.

When a parent has Noonan syndrome, there are major chances of passing a defective gene on to his/her child during birth. Medical studies indicate that the child which inherits the condition from the parent shows few or more symptoms than the parent. To be more precise, kids who have one parental with Noonan disorder who passes the malfunctioning gene (autosomal central) have a 50 percent risk of acquiring the syndrome.(1)

Dominant Genetic Disorder: It involves an abnormal gene from one parent and can result in disease. This is one of several approaches that a characteristic or syndrome can be passed down through the extended family. The risk of Noonan disease growing in the familial of an altered individual is 50% if the parental is altered but is less than 1% if the paternal is unaffected. The risk of communication to the children of an influenced person is 50%. Preimplantation hereditary identification can be recommended in ancestral instances with proven changes. The risk is the same for males and females.

Recessive Genetic Disorder: Recessive disorder involves two versions of an abnormal gene must be present in order for the disease or trait to grow. This disorder results in cystic fibrosis, sickle cell anemia, and Tay Sachs disease. If a person gets one regular gene and one gene for the disorder, the individual will be a transporter for the disorder, but typically will not reveal a warning sign. The probability for two carrier parentages to mutually transfer the malfunctioning genetic factor and, as a result, having an altered infant is 25 percent with every gestation.

Patients with Noonan Syndrome with Hypertrophic Cardiomyopathy have a harsher risk, resulting in substantial early death (22% at 1 year).(2,3)

Is There A Blood Test For Noonan Syndrome?

The most common symptoms of Noonan Syndrome include wide-set eyes broad forehead, drooping face, and a few others.

If Noonan syndrome has been verified or is fervently speculated, additional examinations are required to determine the scope of the symptoms. Recommended approaches may include

  • Treatment of cardiovascular problems
  • Malformation in the bones and ribs treatment
  • Addressing learning disabilities
  • Audio and Visual treatments
  • Treatment for bleeding and bruising

To evaluate the condition, your health care provider will suggest a blood test. Hemophilia is one of the symptoms of Noonan syndrome in which your blood doesn’t clot normally because it lacks sufficient blood-clotting proteins. Therefore, when you have an injury, you bleed longer than usual. A blood test is typically done to determine how well the blood clots.

In addition, blood tests may be requested to determine the growth issues. Based on the results, suitable therapies are suggested as a treatment option.(4,5)


  1. What’s to know about Noonan syndrome? https://www.medicalnewstoday.com/articles/179200.php
  2. Causes of Noonan Syndrome- Rare Disease Database https://rarediseases.org/rare-diseases/noonan-syndrome/
  3. Can females have Noonan syndrome? https://www.aafp.org/afp/2014/0101/p37.html
  4. Diagnosis of Noonan Syndrome https://www.nhs.uk/conditions/noonan-syndrome/diagnosis/
  5. Noonan syndrome: a cryptic condition in early gestation https://www.ncbi.nlm.nih.gov/m/pubmed/10817648/

Also Read:

Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:December 17, 2019

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