Noonan Syndrome
Noonan Syndrome Causes
From its pattern of recurrence, Noonan syndrome had been suggested to be an autosomal dominant genetic defect with variable expression. An NS patient has as much as 50% chance of transmitting it to his child. Some manifestations of NS may be subtle enough to be recognized. NS may sometimes present as heterogeneous with more than a single similar condition with different causes and some are not inherited.
Noonan Syndrome Definition
Noonan Syndrome or NS is classified as a relatively common genetic disease. It is a congenital condition affecting both the male and the female. It was formerly considered as the male counterpart of Turner's syndrome. Despite this comparison, the genetic causes of Noonan syndrome are distinct from Turner syndrome. The clinical presentation of Noonan syndrome is primarily congenital heart malformation, problems with learning, indented chest, short stature, impairment of blood clotting and characteristically configured features of the face. Noonan syndrome acquired its name from Dr. Jacqueline Noonan. Approximately 1 in every 1,000 and 1 in every 2,500 children all over the world are born with this condition. In fact, it is considered as one of the most common genetic diseases with close relation to congenital heart disease with the same occurrence with that of Down syndrome.
Noonan Syndrome Diagnosis
The range and extent of severity is significantly variable among NS patients making this syndrome less identifiable at a very early age.
Noonan Syndrome Symptoms and Signs
Pulmonary valvular stenosis occurs in 50% of NS patients. Gastointestinal problems with difficulty in swallowing and forceful vomiting are common. Almost all males have undescended testicles. Motor delay and poor coordination, mental retardation, speech difficulties, joint or muscle pain, short stature and some characteristic facial features are noted.