What is Noonan's Syndrome?
Noonan Syndrome or NS, is a common congenital genetic disease, which leads to congenital malformation of the heart, short stature, learning problems, indentation of the chest, problems in blood clotting and unique facial features and their configuration. Noonan syndrome affects both the males and females equally and is usually seen amongst every one in 1000 people worldwide. It is very similar to Down’s syndrome, however the severity of the symptoms vary from patient to patient. Thus, it becomes difficult at times to diagnose the disease at an early stage.
Causes of Noonan's Syndrome
Noonan syndrome is an inherited condition and affects the whole body. Research has shown that half of the patients suffering from the Noonan Syndrome carried the mutation of the gene PTPN11, which encodes SHP2 protein. Even though the genetic causes are not identified yet, it is supposed that excessive activity of the SHP-2 may result in the Noonan syndrome. It is inherited as an autosomal dominant pattern and is often seen amongst children who have inherited it from their parents. When a parent is suffering from this syndrome, it is seen that the chances of transmitting the disorder to their children increases by 50%. At times parents carrying the faulty gene do not experience any symptoms and thus the cause of the disease in the child remains unknown. At times, new, sporadic mutations in the gene may also result in the manifestation of the syndrome in the person. Otherwise, mutations in the other genes like KRAS and RAF1 are also reported to have caused the problem though the percentage of cases caused by the mutations in these genes is extremely low.
Symptoms of Noonan's Syndrome
The Noonan Syndrome affects all the body systems and damages them.
Some of the symptoms seen in the disease are:
Effecting the heart – pulmonary valvular stenosis, septal defects (artrial, ventricular), heart murmur, cardiomyopathy;
Effecting the gastrointestinal system – failure to thrive, loss of appetite, digestive problems, frequent vomiting, swallowing difficulties;
Genitor-urinary system – cryptorchidism; lymphatic system – posterior cervical hygroma, lymphedema;
Developmental problems – clumsiness, poor coordination, motor delay, mental retardation, learning disabilities, speech and language delays;
Severe join pain without any apparent cause;
hematologic problems – easy bruising, low platelet count, blood clotting problems, Von Willebrand disease, prolonged activated partial thromboplastin time, deficiency of factor VIII C, XI C, XII C, coagulation disorders; neurological issues like Arnold Chiari malformation etc.
Apart from these factors, there are certain other symptoms which manifest in the form of physical appearances like -- short stature, cervical spine fusion, scoliosis, prominence of breast bone, depression of breast bone, joint contractures or tightness, joint hyperextensibility or looseness, growth retardation, winging of the scapula, hypotonia, excess skin on the back of the neck, low hairline at the nape of the neck, large head, triangular face shape, broad forehead, short neck, webbed neck, posterior cervical, curly hair. Downward sloping eyes, drooping eyelids, visual problems like squint, short sightedness and low-set ears are also few other symptoms to show up.
Diagnosis and Treatment of Noonan's Syndrome
Despite the knowledge of the causative genes, the doctors still diagnose the Syndrome by its manifestations, or in other words, on the clinical features. The doctors might perform a test checking for the mutations in the causative genes (TPN11, SOS1, or KRAS), however in case the test results are negative, and the presence of the disease is not completely ruled out. Thus, the diagnosis of the disease is mostly based on the symptoms the patient shows. In case of pregnant women, a high resolution ultrasound will help determine if the fetus is suffering from the Noonan Syndrome.
The Noonan Syndrome is incurable, but the symptoms like congenital heart defects can be treated with the help of surgical and medical treatments. Other than this, supportive therapies like educational support and speech therapy etc will help the individuals suffering from this disease to live a better life.
