Noonan Syndrome

Noonan syndrome is a genetic condition that halts the normal development of various body parts. It usually results in unusual facial features, short stature, heart problems, intellectual disabilities, other physical changes (Mayo Clinic Staff, 2023). It is commonly compared with Turner syndrome due to the similar presentation between the two. 

Gene mutations that cause Noonan syndrome involve the RAAS and MAPK signaling pathway and it is an autosomal dominant inherited disease (Allen and Sharma, 2023). This means that if you get the mutated gene from one parent, you will be able to get the disease. It is common for diseases with an autosomal dominant pattern to have parents that also have the disease. A parent that has Noonan’s syndrome has a 50% chance of passing the gene to their child (Mayo Clinic Staff, 2023) . 

Specific changes in facial features include: wide-set eyes, low-set ears, depressed nose, mouth with a deep groove between the nose and the mouth, coarse facial features, large head (Mayo Clinic Staff, 2023). However, it is important to note that many patients with Noonan syndrome do not have any clinical presentations as birth. Patients with Noonan syndrome also can present with lymphatic problems, resulting in swelling in the abdominal area along with the extremities. These patients also may bruise easily or bleed easier, due to a factor 11 deficiency, which is involved in the blood clot pathway (Allen and Sharma, 2023). Noonan syndrome can also cause heart problems.  Patients may have pulmonic valve stenosis, which is a narrowing of the valve that is between the heart and the lungs. Patients may also experience thickening of the heart, known as hypertrophic cardiomyopathy (Allen and Sharma, 2023).

Because Noonan syndrome is genetically inherited, there is no treatment. Management of the syndrome is aimed at treating the symptoms, rather than the syndrome itself (Allen and Sharma, 2023). It is important to get routine evaluations done to ensure that symptoms and defects that are present are appropriately managed.  

References:

Allen, M. J., & Sharma, S. (2023, January 9). Noonan syndrome - StatPearls - NCBI Bookshelf. National Library of Medicine. https://www.ncbi.nlm.nih.gov/books/NBK532269/

Mayo Clinic Staff. (2023, May 25). Noonan syndrome. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/noonan-syndrome/symptoms-causes/syc-20354422