Noonan syndrome is an autosomal dominant congenital disorder. It is relatively common and affects somewhere between one in 1,000 and one in 2,500 children worldwide. There are increasing variants in the symptoms of Noonan syndrome; a child can be born with it and suffer from all distinct characteristics, or they may experience only a few and be diagnosed in their teens or as an adult. Caused by a genetic mutation, it is a disorder that comes from an affected gene. The parent of dominant inheritance carries the gene, which prevents normal development in certain parts of the body. It is important to understand the majority of symptoms present in Noonan syndrome, as not all are exposed at the same time.

Facial Features

The facial appearance of a child with Noonan syndrome is the most telling symptom. More pronounced in babies and children, the facial features may change as the child gets older and become more subtle. Those affected may have one or all of the following features. The eyes are usually wide set and will appear to be slanting downwards. The eyelids are often droopy and expressionless or seem to bulge. The irises can be pale blue or green. The ears are low and rotating slightly backward, and the nose will have a broad base, a bulbous end and a groove or depression at the top bridge. The whole face may have a look of vacancy and seem to droop.


Short Stature

Along with distinct facial features, the other specific trait is that of stature. Around 50-70 percent of those individuals with Noonan syndrome will have short stature. Abnormal levels of the growth hormone cause slow growth. However, when they are born, these people will be of normal length and weight. The slow growth symptoms happen over time. When they reach the age of two, the child's progress slows, and the disease becomes more prominent. The average height for women Noonan syndrome sufferers is 5ft or 153cm, and in men, it is 5ft 3im, or 162.5cm. A human growth hormone can sometimes help these children grow and reach normal height, but only if doctors administer the hormone early enough.

height noonan syndrome

Musculoskeletal Issues

Noonan syndrome can cause some unusual skeletal problems. Some of the most common ones are deformities and curvatures of the spine, wide-set nipples, and an unusually shaped chest. The chest shape will most often come with either a deep sunken sternum or a raised, protruding one. The neck is also affected. A typical Noonan sufferer's neck will be short; it may have extra folds of skin, otherwise known as a webbed neck, and tight, prominent neck muscles. This condition is known as trapezius.

skeletal noonan syndrome

Genital Conditions

Problems in the genital area will affect both males and females with Noonan syndrome. However, it is far worse for men. Both boys and girls with this condition will have delayed puberty, but as far as fertility goes, males may not develop normally because the testicles do not descend properly. Males with undescended testicles have cryptorchidism. The condition is common in men with Noonan Syndrome and may also cause small penis size.

genetics noonan syndrome

Skin Conditions

Most commonly, skin conditions that people with Noonan syndrome may experience are coarse or sparse body hair and problems affecting the color and texture of the skin. Specifically, they may have excessive scar formation, called Keloid formation. Hyperkeratosis is also a possibility, which is where there is an overdevelopment of the outer layer of skin, and the formation of darkly pigmented skin spots called pigmented nevi. Connective tissue disease as a skin abnormality is also present.

skin conditions noonan syndrome

Hearing Loss and Ear Appearance

Typically, Noonan syndrome patients will have abnormally shaped ears. In 90 percent of cases, the ears are quite low-set on the head, and they commonly rotate backward. Other visual traits of the ears are an incomplete folding of the ears and a thick outer rim (helix), which is present in over 90 percent of cases. The hearing can also be widely affected. People living with the condition are prone to ear infections and other chronic afflictions.

does my child have noonan syndrome

Symptoms of Noonan syndrome: Bleeding

Noonan syndrome can cause bleeding disorders and other hematologic issues. Because of the low platelet count, otherwise known as Amegakaryocytic thrombocytopenia, this can cause easy bruising and other blood clotting disorders such as Von Willebrand disease. The blood condition can also lead to various combined coagulation defects and deficiencies. These traits of this illness can lead to uncontrolled external or internal bleeding which can cause damage to joints, muscles and internal organs. These symptoms can turn life-threatening if this part of Noonan Syndrome is left untreated.

what is noonan syndrome

Lymphatic Problems

The lymphatic system works by draining excess fluid from the body and fighting off infection. Problems with this system can occur regularly with Noonan syndrome. Most commonly it presents itself as excess fluid found on the top of the feet or the back of the hands. This condition is lymphedema. This liquid can also deposit in other parts of the body as well, widespread or localized. This condition can occur repeatedly at various times in a Noonan syndrome sufferer's life.

 noonan syndrome

Intellectual Disability

Intellectual disability presents in up to 25 percent of children with Noonan syndrome. The disease is also related to some learning disabilities and delayed development. Research shows children affected may exhibit behavioral problems and poor coordination. However, there is no scientific evidence to support these findings. Noonan syndrome has links to autism, speech-language pathology, and other motor development issues. However, there are also cases of adults living with the condition and working in successful careers.

symptoms of noonan

Heart Defect

It is common that people with Noonan syndrome were also born with some form of heart defect. The most common of conditions associated with Noonan's is a valve disorder. A valve disorder is when the pulmonary valve is narrow. The pulmonary valve is the flap of tissue, which separates the ventricle from the pulmonary artery. Sufferers may also experience a thickening of the heart muscle, irregular heart rhythm and structural defects such as holes in the heart walls or narrowing of the aorta

heart symptoms of noonan syndrome


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