There's no evidence to suggest the genetic fault is caused by environmental factors, such as diet or exposure to Faults in at least 8 different genes have been linked to Noonan syndrome. The faulty gene associated with Noonan syndrome can be: Inherited from a parent. Jacqueline Noonan was a pediatric cardiologist who investigated a number of patients with congenital heart disease. So far, four genes have been known to cause noonan syndrome. Noonan syndrome is caused by an abnormality or mutation in one of several genes. Defects in these genes cause the production of proteins that are continually active. These mutations can occur in multiple genes.
However, if you have a family history of this syndrome, talk to your doctor about the benefits of genetic counseling before you have children. Noonan syndrome (NS) is a genetic disorder that may present with mildly unusual facial features, short height, congenital heart disease, bleeding problems, and skeletal malformations. Some heart problems can occur later in life. Intelligence in the syndrome is often normal. The parent carrying the faulty gene will also have the condition themselves, although it may be very mild.In the remaining cases, the condition is caused by a new genetic fault that isn't inherited from either parent.If you have a child with Noonan syndrome and neither you or your partner have been diagnosed with it yourselves, talk to your GP about getting a referral to a genetic counsellor.If neither of you carry one of the faulty genes, the risk of having another child with the condition is very small (estimated to be less than 1%).If one of you does carry a faulty gene or has been diagnosed with Noonan syndrome, there's a 50% risk of each further child you have being born with the condition.A genetic counsellor can explain the risks and your options for having another child. Causes . You or your child may be referred to a geneticist or a cardiologist.If your unborn child is at risk because of a family history of Noonan syndrome, prenatal tests may be available.In an autosomal dominant disorder, the mutated gene is a dominant gene located on one of the nonsex chromosomes (autosomes). Faults in at least 8 different genes have been linked to Noonan syndrome.

Noonan Syndrome Causes. These may include:Noonan syndrome can cause hearing deficits due to nerve issues or to structural abnormalities in the inner ear bones.Noonan syndrome can cause excessive bleeding and bruising due to clotting defects or having too few platelets.Noonan syndrome can cause problems with the lymphatic system, which drains excess fluid from the body and helps fight infection. The most commonly altered genes are:In around 1 in 5 cases, no specific genetic fault can be found.The symptoms of Noonan syndrome are generally similar, no matter which gene is affected. However, individuals may have:A common sign of Noonan syndrome is abnormalities of the eyes and eyelids. Causes Of Noonan Syndrome. You need only one mutated gene to be affected by this type of disorder.

The most common features of Noonan syndrome are: Unusual facial features, such as a broad forehead, drooping eyelids and a wider-than-usual distance between the eyes; Short stature (restricted growth) Heart defects (congenital heart disease) Noonan syndrome is caused by a fault in one of several genes. Issues may include the following:Intelligence isn't affected for most people with Noonan syndrome. Characteristics may be related to the specific gene containing the mutation.Facial appearance is one of the key clinical features that leads to a diagnosis of Noonan syndrome. However, the faulty PTPN11 gene is commonly associated with pulmonary stenosis (a narrowed heart valve) and the faulty RAF1 gene is more often associated with cardiomyopathy (disease of the heart muscle).In around 30-75% of cases, Noonan syndrome is inherited in what's known as an autosomal dominant pattern. Facial features include widely spaced eyes, light-colored eyes, low-set ears, a short neck, and a small lower jaw. The constant activation of protein can disrupt the normal process of cell growth as well as cell division. Noonan syndrome is caused by a genetic mutation and is acquired when a child inherits a copy of an affected gene from a parent (dominant inheritance). Because these genes play a role in the formation of many tissues throughout the body, this constant activation of proteins disrupts the normal process of cell growth and division.A parent with Noonan syndrome has a 50 percent chance (one chance in two) of passing the defective gene on to his or her child. These may include: If you have it, you might have certain identifiable facial features, short height, and unusual chest shape. If you suspect you or your child may have the disorder, see your primary care doctor or your child's pediatrician.